FAQ

This is Leo’s Frequently Asked Questions document.

Learning to use Leo

How can I learn Leo, or python, or anything

Let us think of lessons not as explanations, but as puzzles to be solved by the student. The puzzles themselves need no lengthy explanations. They can even be cryptic. This attitude arises from two principles:

1. The less said, the better.

2. Invite people to learn for themselves.

Pick something that interests you

Pick a real, worthy, programming task that you (the student) personally want/need to do in Leo. This step is essential! It is useless to try to learn in a vacuum.

EKR’s first python program was C2Py. leoAttic.txt contains the original version. Leo’s c-to-python commands contained revised code.

Overcome fear of crashes and mistakes

• Run Leo from a console.

• Single-step through your code with g.pdb()

• Deliberately put a crasher in your code and see what happens.

The only way to hard crash Leo is to pass bad pointers to PyQt. Python should catch all other problems. If it doesn’t, report a bug to the python people ;-)

Discover how Leo’s code works

• Where is Leo’s source code? Hint: look for leoPy.leo in LeoDocs.leo.

• Look at Leo’s demote command. - What are three ways of finding the demote command? - How does demote change the outline? - How does demote handle undo?

• Study any other Leo command that relates to your project.

• Use the cff command to find all definitions of x.

• Use the cff command to find all uses of x.

Start using Leo for real

• Add a new command using @button.

• Create an external file containing your real-world project. Execute it outside of Leo.

• Write a Leo plugin.

• Advanced: fix one of Leo’s bugs.

Attitude

Students should always feel free to ask for help, but struggle teaches us the most. It doesn’t matter how long it takes to learn something. In our culture, we value quickness. But that is a trap. All learning builds momentum:

• Put 10 units of effort in, get 1 unit of results out.

• Put 1 in, get 1 out.

• Put 1 in, get 10 out.

There is no other way! How many times have we given up just because things were not easy or clear at first?

That which we learn, we learn by doing

Reading about (and thinking about) are useful, but not good enough. That is why students must have a project that is important to them. The project will put them into action.

What’s the best way to learn to use Leo?

First, read Leo’s tutorials. This will be enough to get you started if you just want to use Leo as an outliner. If you intend to use Leo for programming, read the scripting tutorial, then look at Leo’s source code in the file LeoPy.leo. Spend 5 or 10 minutes browsing through the outline. Don’t worry about details; just look for the following common usage patterns:

• The (Projects) tree shows how to use clones to represent tasks.

• Study @file leoNodes.py. It shows how to define more than one class in single file.

• Most other files show how to use a single @others directive to define one class.

• Most methods are defined using @others, not section definition nodes.

When is using a section better than using a method?

Use methods for any code that is used (called or referenced) more than once.

Sections are convenient in the following circumstances:

• When you want to refer to snippets of code the can not be turned into methods. For example, many plugins start with the code like this:

  << docstring >>
  << imports >>
  << version history >>
  << globals >>
  
  None of these sections could be replaced by methods.
  

• When you want to refer to a snippet of code that shares local variables with the enclosing code. This is surprisingly easy and safe to do, provided the section is used only in one place. Section names in such contexts can be clearer than method names. For example:

  << init ivars for writing >>
  

In short, I create sections when convenient, and convert them to functions or methods if they need to be used in several places.

Abbreviations

What are some useful abbreviations?

Edward Ream:

alp;;=@language python\n
alr;;=@language rest\n@wrap\n
date;;={|{import time;x=time.asctime()}|}
trace;;=trace = <|bool|> and not g.unitTesting

John Lunzer:

hl;;={|{x=c.p.h}|}
es;;=g.es(contents,color='<|color|>')
ts;;={|{x=time.strftime("%Y%m%d%H%M%S")}|}

Rob (Largo84):

ol;;=<ol>\n    <li><|item|></li>\n</ol>
li;;=<li><|ITEM|></li>
link;;=<a href="<|URL|>" target="_blank"><|TEXT|></a>
enum;;=\begin{enumerate}\n    \item <|item|>\n\end{enumerate}

For more examples, see LeoSettings.leo.

Clones

How can I customize the clone-find-all commands?

The c.cloneFindAllAtNode and c.cloneFindAllFlattenedAtNode methods start the clone-find-all and clone-find-all-flattened commands at a particular node. For example, here is the body of @button cfa-code @args add in leoPy.leo:

c.cloneFindAllFlattenedAtNode('Code',top_level=True)

The @args add part of the headline causes Leo to add the cfa-code command to Leo’s history list, so there is no urgent need to use a separate key binding for this command.

How can I eliminate clone wars?

Clone wars can be most annoying. The solution is simple:

**Keep clones only in the outline and in one other external file**

In particular, catchall files like leo/doc/leoProjects.txt or leo/doc/leoToDo.txt should never contain clones.

How can I use clones to reorganize an outline?

Clones make reorganizing an outline significantly easier and faster. Simply make top-level clones of the nodes you keep encountering during the reorg. This makes moving a node a snap: just move it from one clone to another.

How does EKR use clones?

For the last several weeks I’ve used clones in a new, more effective way, inspired by git’s stash/unstash commands. Here are the main ideas.

1. [Most important] I avoid putting clones in two different external files.

For any task, I create a task node that resides in @file leoToDo.txt. I clone that node and put it in the outline, never in any other @file node. This instantly eliminates clone wars.

2. I use top-level “stashed” nodes/trees in my local copy of leoPy.leo.

These clones are not written to any external file, so they would be lost if I lost leoPy.leo. But the risks are negligible because all stashed nodes are clones of nodes that do exist in external files.

3. I have two main stashed trees: recent files and recent code.

The “recent files” tree contains clones of all the @file nodes I have worked on recently. This speeds up access to them. That happens surprisingly often–often enough to be well worth maintaining the tree. Furthermore, because Leo’s new pylint command now works on trees, I can check all recently-changed files simply by running pylint on the “recent files” tree.

The “recent code” tree is even more valuable, for three reasons. The first is obvious–it speeds access to recently-changed nodes.

Second, the “recent code” tree allows me to work on multiple tasks without getting overwhelmed by details and loose nodes lying around. I add organizer nodes as needed to make accessing the nodes faster, and also to jog my memory about what I was doing when I changed those nodes ;-)

Third, the “recent code” tree allows me not to put clones in the @file leoProjects.txt tree. This leads me to…

4. I use clones in a stylized way when fixing and committing bugs.

I always use clones when working on a project. A “task” node contains clones of all nodes related to the task. The task node typically remains in leoToDo.txt until the task is completely finished. While working on the bug, I create a clone of the task node, and move that clone to the bottom top-level node of the outline. Among other things, this makes it easy to limit searches without actually choosing “suboutline only” in the Find panel. This workflow is decades old.

The following is the heart of the new workflow. When a task is complete, I do the following:

1. First, I create a stashed-task node, containing all the clones that were previously in the task node.

The stashed-task becomes pre-writing for the commit log. The task node instantly becomes pre-writing for the release notes, so if it needs to discuss any code in the clones that have just been moved to the stashed-task node, I write those words immediately, while all details are fresh in my mind.

2. Now I move the cloned task node that is in leoToDo.txt to the appropriate place in leoProjects.txt.

3. Next I do the commit.

The other clone of the task node, and the stashed task node are still within easy reach, and I typically use both nodes to create the commit log. The commit will typically consist of the changed leoToDo.txt and leoProjects.txt and whatever .py files the task itself changed. Happily, leoToDo.txt and leoProjects.txt are now up-to-date because of steps A and B.

4. Finally, I clean up.

I delete the top-level clone of the task node, and move the stashed-task node to the “recent code” tree.

5. Later, when it appears that activity has died down on various projects, I’ll delete nodes from the “recent files” an “recent code” trees. This is a minor judgment call: I want to leave nodes in the trees while they are useful, but not significantly longer than that. I do not regard these trees as permanently useful. leoProjects.txt should contain all permanent notes about a project.

===== Conclusions

This work flow may seem complicated. Believe me, it is not. It’s easier to use than to describe.

This workflow has big advantages:

1. Clone wars are gone for good.

2. All recent data is easily available.

3. Task nodes and stashed-task nodes provide natural places for proto-documentation.

4. Banning clones from leoProjects.txt forces me to complete the first draft of the documentation before committing the fix.

How does Leo handle clone conflicts?

Some people seem to think that it is difficult to understand how Leo handles “clone wars”: differing values for a cloned nodes that appear in several external files. That’s not true. The rule is:

**The last clone that Leo reads wins.**

That is, for any cloned node C, Leo takes the value of C.h and C.b to be the values specified by the last copy that Leo reads.

There is only one complication:

**Leo reads the entire outline before reading any external files.**

Thus, if C appears in x.leo, y.py and z.py, Leo will choose the value for C in x.py or y.py, depending on which @<file> node appears later in the outline.

Note: Whenever Leo detects multiple values for C when opening an outline, Leo creates a “Recovered nodes” tree. This tree contains all the various values for C, nicely formatted so that it is easy to determine where the differences are.

When is deleting a node dangerous?

A dangerous delete is a deletion of a node so that all the data in the node is deleted everywhere in an outline. The data is gone, to be retrieved only via undo or via backups. It may not be obvious which deletes are dangerous in an outline containing clones. Happily, there is a very simple rule of thumb:

Deleting a non-cloned node is *always* dangerous.
Deleting a cloned node is *never* dangerous.

We could also consider a delete to be dangerous if it results in a node being omitted from an external file. This can happen as follows. Suppose we have the following outline (As usual, A’ indicates that A is marked with a clone mark):

- @file spam.py
    - A'
        - B
- Projects
    - A'
        - B

Now suppose we clone B, and move the clone so the tree looks like this:

- @file spam.py
    - A'
        - B'
- Projects
    - A'
        - B'
    - B'

If (maybe much later), we eliminate B’ as a child of A will get:

- @file spam.py
    - A'
- Projects
    - A'
    - B

B has not been destroyed, but B is gone from @file spam.py! So in this sense deleting a clone node can also be called dangerous.

When may I delete clones safely?

Q: When can I delete a clone safely?

A: Any time! The only time you can “lose” data is when you delete a non-cloned node, save your work and exit Leo.

Q: What gets “lost” when I delete a non-cloned node?

A: The node, and all it’s non-cloned children. In addition, if the node contains all clones of a cloned node, all copies of the cloned node will also be “lost”.

Q: Anything else I should be careful about concerning clones?

Not really. If you move any node out “underneath” an @file (@clean, etc) node, the contents of that node disappears from the external file.

I hope this encourages more people to use clones. Leo’s clone-find commands are something that every Leo programmers should be using every day.

Why doesn’t Leo support cross-outline clones?

Any outline (.leo file) may contain clones that appear in multiple external files defined within that outline. There is no problem with such intra-outline clones.

In contrast, cross-outline clones are clones that appear in more than one outline. Leo’s paste-retaining-clones command makes it possible for two outlines to contain nodes with the same gnx. Conceivably, both outlines could use those clones in the same external file!

Leo will never encourage cross-outline clones, because such clones are inherently dangerous. Indeed, neither outline would have full responsibility for its own data.

Indeed, the shared clones would be subject to the well-known multiple-update problem. Suppose the two outlines were open simultaneously, and each outline changed the shared clones in different ways. Whichever outline changed the data last would “win.” The changes in the other outline would be lost forever!

In short, Leo will never support features that encourage cross-outline clones.

Why is Alt-N (goto-next-clone) important?

clone-find-all-flattened often includes clones of nodes whose location is unclear. No problem! Just select the mysterious node and do Alt-N (goto-next-clone). Leo will select the next clone of that node, wrapping the search as necessary. One or two Alt-N takes me to the “real” node, the node having an ancestor @<file> node.

Ideally, the meaning of all nodes would be clear from their headlines. I typically use the following conventions. For section definitions, the headline should contain file or class name. Examples:

<< imports >> (leoCommands.py)
<< docstring >> (LeoApp)

Why should I use clones?

You will lose much of Leo’s power if you don’t use clones. See Clones and Views for full details.

Customizing Leo

How can I create a pane for matplotlib charts?

I’m trying to create a interactive chart in a embedded in a new leo pane using matplotlib. However, I am not sure about the the best way to implement this. I would appreciate some guidance on this please? The questions I would like answered are:

1. How do I create a new blank pane for embedding a chart as well as other QtWidgets.

2. Can I do this in a script or do I need to work with leo source?

I want to create a data processing and visualization tool kit in leo. Like Excel but using nodes instead of columns. Nodes will have data and I want to create new data nodes by applying python functions to data in existing nodes. The thing missing is the visualization within a leo pane (I can easily launch a chart in it’s own window).

Terry Brown

You can run this script from any body pane:

'''
A script that adds a MatPlotLib pane to Leo.

After running this script, right click on one of the pane dividers and
select Insert. A new pane with a button 'Action' appears. Click it, and
select "Add matplot" from the context menu.
'''

from leo.core.leoQt import QtWidgets

class MatplotPaneProvider:
    def __init__(self, c):
        self.c = c
        if hasattr(c, 'free_layout'):
            splitter = c.free_layout.get_top_splitter()
            if splitter:
                splitter.register_provider(self)
    def ns_provides(self):
        return[('Add matplot', '_add_matplot_pane')]
    def ns_provide(self, id_):
        if id_ == '_add_matplot_pane':
            c = self.c
            w = QtWidgets.QSlider() ### w = myMatplotWidget()
            return w
    def ns_provider_id(self):
        # used by register_provider() to unregister previously registered
        # providers of the same service
        # provider ID is not the same as the service id_ above
        return "completely unique value here"

MatplotPaneProvider(c)

OP

I have managed to get a matplotlib graph embedded within a pane in leo as a widget. I now need some help with how to interact with the widget using scripts in leo. I am unsure about the following:

1/ How do I expose the widget within the leo environment?

If you were only going to have one and you weren’t going to destroy it, you could just do something simple like c._matplot = self in its constrictor (assuming c was passed to the constructor).

If you’re going to have more than one and they may be destroyed, it might be simplest to let the free_layout / nested_splitter system manage them:

ts = c.free_layout.get_top_splitter()
matplotters = ts.findChildren(myMatplotWidget)

should return a list of the widgets of your class in the layout, but only if they’re in the main window, widgets in extra windows opened from the “Open window” context menu item would be missed, I can add a find_children() method to complement the find_child() method the splitters already have to account for this.

Detail: the above is just using Qt’s QObject.findChildren(), the nested_splitter find_child() and (not yet written) find_children() versions search the extra windows as well.

Here I have created a self.mat in your MatplotPaneProvider class to make the widget accessible but it doesn’t feel like the correct way to do this:

mat = MatplotPaneProvider(c)
mat.mat.someMethod()
mat.mat.someOtherMethod()

2. I would also like to make the widget accessible from any script within leo. What’s the leo way of doing this?

See above

3. If I create more than 1 pane containing these widgets. How do I switch between them in scripts?

See above

4. Running this script more than once creates multiple items for Add Matplot when pressing the Action button. How do I stop this from happening? I have already tried returning a unique integer in * ns_provider_id but that did not work.

The value returned by ns_provider_id should be unique for the provider class, but constant. So it can just return something like “matplotlib provider ver 1”

How can I customize settings for a particular external file?

How it is possible to specify settings in @file? As I understand every setting should be a single outline.

Vitalije:

You can use clones. For example:

--@settings
----my-shared-settings
------...
----some-specific-settings-for-this-outline
------....

--@file my-shared-settings-somewhere.txt
----my-shared-settings

where my-shared-settings node is cloned from the @file subtree.

Quite often I use some script to combine some nodes, process them and generate some output file. And such script I put in a node with the following headline: @button n-save @key=Ctrl-s. Then whenever I open this outline and whenever I hit Ctrl-s to save the outline, this script is executed. Of course I put in this script c.save() call and on every save my files are regenerated.

When working for a web I often use Coffeescript, some html template generators like Pug, Sass for generating css files, … Now all of these command line tools have watching mode where they watch folders for file changes and whenever source file is changed they regenerate the output file. But then you also need to run some packaging tool to bundle all generated files. Instead of watching for file changes, my script bound to Ctrl-s regenerate source files in memory and without saving them execute suitable tool only on changed sources and produced outputs bundle in the final file. This makes the whole process much faster.

Attached to this message is a Leo file that I have extracted from one of my projects. I hope that I didn’t miss anything that the script require.

In the outline you can find build server implemented in Coffeescript. You have to use npm or yarn to install necessary modules for this server to work. Once installed you start server by executing coffee tools/build-server.coffee and it will start listening on port 8011. The script bound to Ctrl-s will search outline for nodes with the headlines like: @vendor, @pug, @coffee, @bulma and for each found node, it checks if the content of this node and its subtree has changed since last time and if it is, this content is sent to build server which transforms the source and returns result that script writes to output file.

There is one more thing I use for sharing outlines. There are three commands set-reference-file, update-ref-file and read-ref-file. The first lets you choose a reference file for this outline, i.e. public shared outline. It adds a top level headline —begin-private-area— to the outline. In the body of this node is the path to the public Leo file. Everything below this node is private, and above is public. The public file should be added to version control (git, fossil,…) and the private file should be added to ignored files for version control tool. And then in the script bound to Ctrl-s you can add c.fileCommands.save_ref(), so every time you save your private Leo file, at the same time is updated the public Leo file. That way they never get out of sync.

How can I enable and disable support for psyco?

Find the @file leoApp.py node in leoPy.leo. In the ctor for the LeoApp class set self.use_psyco to True or False. You will find this ctor in the node:

Code-->Core classes...-->@file leoApp.py-->app.__init__

Note that this ivar can not be set using settings in leoSettings.leo because Leo uses g.app.use_psyco before processing configuration settings.

How can I modify an existing theme?

In the directory leo-editor/leo/themes are a number of theme files. These can be loaded using the File, Open Outline menu option in Leo. Opening an outline automatically loads it. Keep opening outlines until you find one you like.

Then close all of the theme files.

Copy the theme file you chose from leo-editor/leo/themes to ~/.leo/themes (you will have to create the themes folder here) and rename it something like this: Original file is BreezeDarkTheme.leo rename to BreezeDarkThemeLocal.leo

Now open your myLeoSettings.leo file.

Add the following to the headline of a new node as a child of your @settings node:

@string theme-name = BreezeDarkThemeLocal

Now save the file and restart Leo.

You should now be using the theme of your choice. From here you need to open the local theme file with Leo. The font sizing and colors are under Theme Settings in the tree.

How can I put background images in the body pane?

Put the following in the style-sheet:

QTextEdit#richTextEdit { background-image: url(‘/home/tbrown/Desktop/cow2.jpg’); }

If you wanted node specific backgrounds Leo would have to start setting an attribute on the body widget, probably the gnx, so you could do:

QTextEdit#richTextEdit[leo_gnx='tbrown.20130430222443.19340'] {
    background-image: url('/home/tbrown/Desktop/cow2.jpg');
}

How can I run code at startup?

The following plugin, placed in ~/.leo/plugins, runs code at ‘start1’ time, that is, while other plugins are loading:

import leo.core.leoGlobals as g
print('===== local_plugin.py in ~/.leo/plugins/')

def hook(tag, keys):
    g.trace(tag)

def init():
    g.registerHandler('start1', hook)
    return True

Alternatively, the plugin could run code at ‘start2’ time, after all plugins have been loaded, or at any other time, as described on this page.

How can I sync settings across .leo files?

Organize your myLeoSettings.leo file like this:

@settings
     -my settings <clone>
          -@bool .... = True
          -@data fldsdf

@file mysettings.txt
      my settings <clone>

Syncing mySettings.txt will synchronize your settings across your .leo files.

Note: Changed settings will not be available in other open outlines until you reload settings. You can do this with the reload-all-settings command.

How do I enable a theme .leo file?

To enable a theme .leo file, put the following setting in myLeoSettings.leo:

@string theme-name = <theme file, without the .leo extension>

Dark themes:

@string theme-name = BreezeDarkTheme
@string theme-name = EKRDark
@string theme-name = LeoBlackSolarized
@string theme-name = ZephyrDarkTheme

Light themes:

@string theme-name = DefaultTheme
@string theme-name = EKRLight
@string theme-name = PaperLightTheme

You can also define a theme directly in myLeoSettings.leo as follows:

• Remove (or disable) any previous @theme tree in myLeoSettings.leo.

• Select one of the @theme trees in leoSettings.leo.

• Copy the entire @theme tree to myLeoSettings.leo.

• Move the copied tree to the end of the @settings tree.

• Test by restarting Leo.

How can I use Leo’s legacy key bindings?

You can ‘revert’ to old key bindings as follows:

1. Open leoSettings.leo.

2. Find the node ‘Keyboard shortcuts’.

3. Disable the old bindings by moving the node ‘@keys EKR bindings: Emacs keys + modes’ so that it is a child of the node: ‘@ignore Unused key bindings’.

4. Notice that there are two child nodes of the node ‘@ignore Unused key bindings’ that refer to legacy key bindings:

   • ‘@keys Legacy Leo shortcuts with important Emacs bindings’

   • ‘@keys Legacy Leo bindings’.

5. Move one of these two legacy nodes up one level so that it is a child of the node ‘Keyboard shortcuts’. It should not be a child of the node ‘@ignore Unused key bindings’.

How do I add a new menu item from a plugin?

c.frame.menu.createMenuItemsFromTable will append items to the end of an existing menu. For example, the following script will add a new item at the end of the ‘File’ menu:

def callback(*args,**keys):
    g.trace()

table = (("Test1",None,callback),)

c.frame.menu.createMenuItemsFromTable('File',table)

Plugins can do anything with menus using c.frame.menu.getMenu. For example, here is a script that adds a Test menu item after the ‘Open With’ menu item in the File menu:

def callback(*args,**keys):
    g.trace()

fileMenu = c.frame.menu.getMenu('File')

# 3 is the position in the menu. Other kinds of indices are possible:

fileMenu.insert(3,'command',label='Test2',command=callback)

How do I set selection colors and fonts?

See the node @data qt-gui-plugin-style-sheet in your theme file or myLeoSettings.leo.

How do I submit a plugin?

You have two options:

• Get git write access, and add the @file file to the plugins directory.

• Just send the @file file to me at edreamleo@gmail.com.

Excel

How can I show Leo files with Excel?

Using Leo’s File-Export-Flatten Outline commands creates a MORE style outline which places all Leo body sections on the left margin. The headlines are indented with tabs which Excel will read as a tab delimited format. Once inside Excel there are benefits.

1. The most obvious benefit inside Excel is that the body sections (Excel first column) can be selected easily and highlighted with a different font color. This makes the MORE format very readable. Save a copy of your sheet as HTML and now you have a web page with the body sections highlighted.

2. It is possible to hide columns in Excel. Hiding the first column leaves just the headlines showing.

3. Formulas based on searching for a string can do calculations in Excel. For example if a heading “Current Assets” appears on level 4 then the body formula:

   =INDEX(A:A,MATCH("Current Assets",D:D,0)+1)
   

will retrieve it. The +1 after match looks down one row below the matched headline. The trick is to place all your headlines in quotes because Excel will see + “Current Assets” from the MORE outline. When Excel tries without the quotes it thinks it is a range name and displays a #N/A error instead of the headline. Also you must place a child node below to get the + sign instead of a - sign which would give a MORE headline of -“Current assets” , also is an error.

I think there is some interesting possibility here because of the enforcement of Leo body text being always in the first column. The Leo outline provides additional reference to organizing the problem not typical of spreadsheet models. Beyond scripting in Python, Excel is good at doing interrelated calculations and detecting problems like circular references. In Excel Tools-Options-General is a setting for r1c1 format which then shows numbers instead of letters for column references. Using this would allow entries like this in the leo body:

1000
3500
=R[-1]C+R[-2]C

In Excel you would see 4500 below those two numbers. This is completely independent of where the block of three cells exists on the sheet.

Files

Can @file trees contain material not in the external file?

No. Everything in an @file trees must be part of the external file: orphan and @ignore nodes are invalid in @file trees. This restriction should not be troublesome. For example, you can organize your outline like this:

+ myClass
..+ ignored stuff
..+ @file myClass

(As usual, + denotes a headline.) So you simply create a new node, called myClass, that holds your @file trees and stuff you don’t want in the @file trees.

How can I avoid getting long lines in external files?

Question: I must follow a coding standard when writing source code. It includes a maximum line length restriction. How can I know the length of a line when it gets written to the external file?

Answer: If a node belongs to a external file hierarchy, its body might get indented when it is written to the external file. It happens when an @others directive or a section name appears indented in a higher-level node body. While (line, col) in status area show the line and column containing the body text’s cursor, fcol shows the cursor coordinate relative to the external file, not to the current node. The relation fcol >= col is always true.

How can I create a template .leo file?

Question: It would be nice if Leo could open empty files. I tend to be “document oriented” rather than “application oriented” in my thinking and prefer “create empty file at location -> open it with program” to “start program -> create new file -> save it at location”.

Answer by Paul Paterson: If you are on Windows 98/2000/XP then the procedure is as follows…

1. Start Leo

2. Click New

3. Click Save as…

4. Save the file as “c:\windows\shellnew\leofile.leo” (or c:\winnt for 2000/XP)

5. Open regedit “start…run…regedit”

6. Open HKEY_CLASSES_ROOT and find the “.leo” extension type

7. Go New … Key from the context menu

8. Call the new key ShellNew

9. Select the new key, right-click, choose New…String Value from the context menu

10. Call it FileName

11. Double-click on the string, and modify it to be the filename of the leofile.leo file you created, including the extension

12. Exit the registry editor and restart Windows Explorer (you may need to reboot on Windows 98)

Now you should have a New:Leo File option in Explorer. This creates a duplicate of the file you saved. This can be useful because you could make a template Leo file containing some standard nodes that you always have and then save this.

How can I create Javascript comments?

Question: I’m writing a Windows Script Component, which is an XML file with a CData section containing javascript. I can get the XML as I want it by using @language html, but how can I get the tangling comments inside the CData section to be java-style comments rather than html ones?

Answer: In @file trees you use the @delims directive to change comment delimiters. For example:

@delims /* */
Javascript stuff
@delims <-- -->
HTML stuff

Important: Leo can not revert to previous delimiters automatically; you must change back to previous delimiters using another @delims directive.

How can I disable PHP comments?

By Zvi Boshernitzan: I was having trouble disabling ‘<?php’ with comments (and couldn’t override the comment character for the start of the page). Finally, I found a solution that worked, using php’s heredoc string syntax:

@first <?php
@first $comment = <<<EOD
EOD;

// php code goes here.
echo "boogie";

$comment2 = <<<EOD
@last EOD;
@last ?>

or:

@first <?php
@first /*
*/

echo "hi";

@delims /* */
@last ?>

How can I open special .leo files easily?

You can open files such as CheatSheet.leo, quickstart.leo, leoSettings.leo, myLeoSettings.leo and scripts.leo with commands starting with ‘leo-‘.

<Alt-X>leo-<tab> shows the complete list of commands:

leo-cheat-sheet
leo-dist-leo
leo-docs-leo
leo-plugins-leo
leo-py-leo
leo-quickstart-leo
leo-scripts-leo
leo-settings

How can I specify the root directory of a thumb drive?

Use the %~dp0 syntax. Example:

%~dp0\Python27\python.exe %~dp0\Leo-editor\launchLeo.py

http://ss64.com/nt/syntax-args.html http://stackoverflow.com/questions/5034076/what-does-dp0-mean-and-how-does-it-work

FYI, this FAQ entry fixes the following bug: https://bugs.launchpad.net/leo-editor/+bug/613153 unable to describe root directory on thumb drive

How can I use Leo with older C compilers

By Rich Ries. Some older C compilers don’t understand the “//” comment symbol, so using @language C won’t work. Moreover, the following does not always work either:

@comment /* */

This generates the following sentinel line:

/*@@comment /* */*/

in the output file, and not all C compilers allow nested comments, so the last */ generates an error. The solution is to use:

#if 0
@comment /* */
#endif

Leo is happy: it recognizes the @comment directive. The C compiler is happy: the C preprocessor strips out the offending line before the C compiler gets it.

How can I use Leo with unsupported languages?

The @first directive is the key to output usable code in unsupported languages. For example, to use Leo with the Basic language, use the following:

@first $IFDEF LEOHEADER
@delims '
@c
$ENDIF

So this would enable a basic compiler to “jump” over the “true” Leo-header-lines. Like this:

$IFDEF LEOHEADER <-conditional compilation directive
#@+leo-ver=4 <-these lines not compiled
#@+node:@file QParser005.INC
#@@first
#@delims '
'@@c
$ENDIF <-... Until here!
<rest of derived code file ... >

This changes the comment symbol the apostrophe, making comments parseable by a BASIC (or other language.)

How do I inhibit sentinels in external files?

Use @clean trees. Files derived from @clean trees contain no sentinels. However, Leo can update @clean trees from changes made to the corresponding external file. The Mulder/Ream update algorithm makes this magic happen.

How do I make external files start with a shebang line?

Use the @first directive in @file or @clean trees. The @first directive puts lines at the very start of files derived from @file. For example, the body text of @file spam.py might be:

@first #! /usr/bin/env python

The body text of @file foo.pl might be:

@first #/usr/bin/perl

@first directives must be the very first lines of @file nodes. More than one @first directive may exist, like this:

@first #! /usr/bin/env python
@first # more comments.

How do I prevent Leo from expanding sections?

Use @asis trees. Files derived from @asis trees contain no sentinels. Leo creates the external file simply by writing all body text in outline order. Leo can’t update the outline unless the external file contains sentinels, so Leo does not update @asis trees automatically when you change the external file in an external editor.

Why can’t I use @ignore directives in @file trees?

@ignore can only be used in the root node of @file trees. It tells Leo to ignore the tree.

The @ignore directive can not be used elsewhere in @file trees because of the way Leo recreates outlines from external files. This is an absolutely crucial restriction and will never go away. For a few more details, see Leo 4.0: Eliminating error ‘recovery’ in History of Leo.

There are several workaround, as shown in LeoPy.leo:

• keep notes in the outline outside of any external file.

• Use @all to gather notes in a external file, as in done in @file leoProjects.txt.

Git

How can I use git to check Leo’s importers?

When I study a program, I like to import it into Leo. I have several scripts that do this: some create @auto nodes; others create @file nodes. Whatever the method used, the import process has the potential to change many files. Usually, I just change @auto and @file to @@auto or @@file, so that any changes I make while studying the code won’t affect the originals.

But this “safety first” approach means that I can’t actually use Leo to insert tracing statements (or for any other changes.) Happily, there is a way to import “live” code into Leo safely:

Create a git repository for the code before importing it

The Aha is to create the repository wherever the code is, including, say, python/Lib/site-packages.

• git diff ensures that import hasn’t significantly altered the code,

This is exactly what I need: I can make changes to important tools safely within Leo.

How can I use Leo with git?

Imo, git rivals python as the greatest productivity tool ever devised for programmers.

My workflow on Ubuntu and Windows is essentially identical. Simple aliases (Ubuntu) and .bat files (Windows) support the following console commands:

gs  (expands to git status)
gd (git diff)  Uses an external diff program,
               but I'm starting to prefer text diffs.
ga . (git add .)
ga file (git add file)
gc (git commit: configured to open Scite to create a commit message)
gc -m "a one-line commit message"
push (git push)

I use gitk on both platforms to review commits.

And that’s about it. I use “git help” and “git help command” as needed.

How should I use Leo with git, etc.?

Use @clean or @auto unless everyone in your work group uses Leo. In that case, using @file is best. Use local copies of reference .leo files instead of the reference files themselves.

What is a reference .leo file?

leoeditor/leo/core contains a reference .leo file: LeoPyRef.leo.

This file should change only when adding new external files to Leo.

Developers should use a local copy of LeoPyRef.leo (conventionally called leoPy.leo) for their own work.

Why do files sometimes change when switching branches?

Private copies of LeoPyRef.leo, that is, leoPy.leo, are “global”. That is, they persist unchanged when switching branches. In effect, they act like (sometimes) unwanted caches.

If you change the structure of @file nodes in leoPy.leo in one branch, such changes will “propagate” to other branches, even though the contents of each node has remained the same.

You can see such changes clearly using leo –diff.

In short, don’t make unnecessary structural changes in leoPy.leo when in branches other than master.

Graphics

How can I display graphics in Leo?

One way is to link directly to the media file from a Leo node (with @url) and write a script button to wrap all URL-nodes under the current node in a single HTML page. Then, you can view your media in two ways:

• Individually. You can directly click on the @url link to display the media in the browser (assuming you have your MIME/filetype associations set up correctly for your browser).

• In a group. You can click on a script button (you have to code this yourself, very simple) which should collect all @url nodes under the current node and dynamically generate a HTML page displaying either links to or embedded versions of the media (using the HTML trick described above to invoke the browser). This way, you can create collections of @url nodes under a single node (like a bookmark folder), and press a single button to view the @url collection as a single entity in the browser (with all browser capabilities like displaying the media).

You could probably generalize this idea of “collect all @url nodes under current node and display as HTML in browser” into a general-purpose plugin. However, the plugin would have to be somewhat smart in mapping a link to its corresponding HTML code (e.g. an image link gets mapped to an <img> HTML tag, a link to a Flash file gets mapped to an <embed> tag, etc).

How can I make a screencast?

Making screencasts is a lot easier than you probably think. Here are some tips to get you started quickly.

Use a script to open your app

The primary purpose of this script is to open your app at a fixed, unchanging size. This is surprisingly important:

• It ensures that the window will always render to pixels in the same way.

• It makes it easier to splice in new video to an existing video.

• It makes it easier to plan your video to ensure everything will appear as you expect.

• It provides continuity when making a series of videos.

Here is a script that I use when making Leo’s screencasts:

python launchLeo.py --gui=qttabs
--window-size=682x1264 <list of .leo files> %*​

This particular –window-size causes Camtasia to create a window whose actual size is 720x1280, the nominal 720p resolution. It may prevent text blur. Or not. I do know that Leo’s screencasts look great at 720p.

Debug your workflow with short videos

Make sure that you can actually upload excellent quality videos before doing anything else. This step is crucial. If you skip this step, all of your initial recording an post-production work could be utterly wasted.

Use short (10-second) test videos at this step. Their primary purpose verify that you can can get to the end of the production process successfully. You are going to make lots of mistakes here: using short videos helps you make these mistakes quickly.

Don’t even think about making longer videos until the answers to all the following questions are clearly “yes”:

• Is your camera working?

• Is your microphone working?

• Do you know how to record your voice and screen?

• Can you log into YouTube or screencast.com?

• Can you upload to YouTube or screencast.com?

• Is the sound in your uploaded video great?

• Do the pixels in your uploaded look great?

This last item is particularly important. Just because pixels look good in your video editor is no guarantee that they will look good when uploaded.

You are ready to try your first “real” take only when you can upload a video that looks and sounds great.

Emulate the screencast.com tutorials

Before rushing right out and making your first video, I recommend watching the tutorial screencasts at screencast.com: http://www.techsmith.com/tutorial-camtasia-8.html

Watch the tutorials to see how the presentations themselves are organized. Watch them until it feels natural to emulate their style.

If you will be using Camtasia, you will also want to watch the tutorials to learn how Camtasia works.

Record your first real take

Now it’s time to go beyond test videos. Even now, though, I recommend keeping your first efforts short: one minute or so. Again, this saves time. You’ll ending up throwing away two or three anyway ;-)

Bring up your app using you demo script and run through your presentation.

Here’s the most important tip: As you narrate your video, audio flubs are inevitable, but they don’t matter at all provided that you realize that you have just flubbed a word or phrase.

When you flub a line, don’t panic! Just pause, regroup, and repeat the phrase until you get it right. Pausing is essential: it simplifies inserting and deleting sound bites during post production.

You’ll relax once you realize that flubs don’t matter and that pausing makes post-production easier. Once you relax, getting a good take will suddenly become easier.

Correcting flubs as soon as they happen is absolutely essential. Don’t even think about fixing audio flubs in post-production. It simply can’t be done. Instead of spending 20 minutes trying (and failing) to correct a flub in post production, it is much faster and better to take 20 seconds during your take to correct the flub.

Similar remarks apply to video, but in my experience it’s much easier to get the video right. If you do flub the video, it will be much easier if you just do a complete retake. With Camtasia, you can separate the audio and video tracks, but usually that won’t work, especially if there is audio of key clicks.

By retaking audio flubs as they happen, I find it easy to work without a script. It feels more natural to me than reading a script. YMMV. When I get stuck, I just pause. Or just start over. Otoh, it wouldn’t be that hard to read a script. Just pause before and after each phrase. Never rush your audio!

In short, the key Aha is: insert (audio) pauses everywhere as needed. It’s easy to edit them out. It’s virtually impossible to edit in the middle of words, even with the world’s best audio editor.

Edit your raw take

Post production should be easy provided that you have corrected all audio flubs as they happen. This keeps the audio and video in sync. Just edit out flubs and reduce overly-long pauses.

I won’t discuss production details here because they depend on the editor you are using.

Do a new take if you don’t have clean audio. Depending on the complexity of your video, it may be possible to splice a partial take in the middle or end of your video. Similarly, it may be possible to splice in a new take to add material you didn’t cover in your first take.

One final word of advice. When editing your video, settle for “good enough”. Perfectionism is not your friend.

Summary

Making a screencast is a lot easier than you think :-)

• Create a script that will open your app at a fixed, optimal, size.

• Emulate the style and form of screencast.com tutorials.

• Verify the entire production process with short test videos.

  Before making longer videos, make sure that the test videos look and sound great when they have been uploaded.

• When doing a take, flubs don’t matter, provided you correct them during the take. Use pauses. Make haste slowly!

• Splice in new takes during post-production to fix flubs and add new material.

Additional tips

Here are some more tips I’ve learned from experience:

1. Redo audio tests and video tests every time you start a new session. It’s amazing how hum can creep into recordings.

2. The most important step in post production is to get the pacing so it feels right. Beware of editing out pauses. Make sure you give your viewers time to see what you are doing, and to see what you have done.

3. Don’t waste time on callouts or captions until the audio and video work together at a relaxed pace. It’s almost as hard to correct pacing mistakes as it is to correct audio flubs.

Tips for improving audio

1. Enable volume leveling and noise removal in Camtasia. This tip, all by itself, makes a big difference.

2. Use a better microphone, preferably one with about a 1-inch diaphragm. This is the kind of microphone that Andrew Price uses. The Audio-technica AT2020 USB is relatively inexpensive.

3. Use “pop filter” with the microphone. This is a cloth or (better) a metal screen that is placed in front of the microphone. It smooths the sound.

4. Adjust the sound level for maximum volume without distortion: With the microphone about a foot from your mouth, turn the volume as loud as possible, then turn down until no red is visible in the meter.

Importing files

How can I import many files at once?

The Import Files dialog allows you to select multiple files provided you are running Python 2.3 or above. There is also an importFiles script in LeoPy.leo. You can use that script as follows:

import leo.core.leoImport as leoImport
leoImport.importFiles(aDirectory, ".py")

This will import all .py files from aDirectory, which should be a full path to a particular directory. You could use “.c” to import all .c files, etc.

LaTeX

How can I produce PDF output from LaTex input?

From this long discussion on leo-editor:

From Rob Keeney:

Typical Use case

I teach a variety of classes in a business environment and need handouts, teaching aids, worksheets and training manuals that are specifically customized for each client. These documents are easier to manage, print and protect using standard PDFs.

Workflow Overview

• Document content comes from a primary resource directory arranged by topic (not client specific).

• I have a Resources.leo file that helps me keep that directory organized.

• All of the content files are written in LaTex (I use a .txi file extension of my own invention to indicate the file is an ‘input’ file only, not the main output file which uses .tex).

• I have a Client.leo file for each client in their own directory to organize work specific to each client.

• For each document needed for a client project, I create a Document.tex file from a standard template and change the document properties as needed for the specific client, project and document.

• The Document.tex file acts as the presentation ‘shell’ for the document and I simply add input{”ResourcePath Content.txi”} after the begin{document} statement (ResourcePath is a shortcut command to the location of the content resource). This shell determines such things as the document title, document type, client name, header/footer information and revision date.

• Since I work primarily in Windows, I use TeXNicCenter to process (typeset) the Document.tex file to create PDF output. (I do not use TeXNicCenter for editing, only file processing).

Workflow Notes and Shortcuts

• Years ago, I discovered the incredible exam class for LaTex and now use it almost exclusively. It makes it much easier to create student and teacher versions of the same content (for example, handouts for students and training manual with speaking notes for the teacher).

• I use @outline-data tree-abbreviations in Leo to create each new Document.tex file from a template with variables (very cool!)

• I created many @data abbreviations in Leo to speed up typing of standard LaTex structures (would be happy to share them if anyone is interested).

• All document content stays in the Resources directory and only ‘shell’ documents are in the client directories.

• These shell documents allow for client-specific information to be added to the headers, footers and in some cases as variables inside the content area itself (using theClient variable that I define).

Software Needed

• Leo, and its dependencies.

• MiKTex for the LaTex distribution and package management (I have it set to auto-update as needed).

• TeXNicCenter for processing (typesetting) to PDF output.

Example Leo file

See this example Leo file.

Questions

Q: Can you control TexNicCenter from Leo - or do you process the file and preview process manually?

A: No, I run processing (typesetting) in TeXNicCenter manually. Typically, I create a blank project file and open however many files required for that project. That way it’s easier to clean up the extra files created during the process steps. HTH. There might be a way to invoke the LaTex commands through Leo, but that’s way above my pay grade.

From Arjan Mossel:

I’m using Leo to organize sections like chapter, section and subsection. Since I’m just writing latex in Leo, I need to keep track of the right hierarchies, so I can’t freely move nodes around in the hierarchy or I end up with subsection at the same level as section, etc. It would be great to be able to let Leo handle this.

MyProject

• @clean myproject/myproject.tex

• @clean myproject/references.bib

• Compile myproject.tex

The compile node has something like this:

import os
import subprocess
import sys

repository_dir = os.path.abspath(os.curdir)

# Run the system commands from the folder containing the tex, cls, clo, or bib files.
working_dir = os.path.join(repository_dir, 'myproject')
os.chdir(working_dir)

# The commands to run.
run_xelatex = 'xelatex ' + working_dir + os.sep + 'myproject.tex'
run_bibtex =  'bibtex ' + working_dir + os.sep + 'myproject'

g.es('Running XeLaTeX and BibTeX')
# os.system starts a new subshell
# @todo: is it possible to run the below commands in one subshell consecutively?
os.system(run_xelatex)
os.system(run_bibtex)
os.system(run_xelatex)

# Platform-independent file opening
def open_file(filename):
    if sys.platform == "win32":
        os.startfile(filename)
    else:
        opener ="xdg-open"
        subprocess.call([opener, filename])

open_file('myproject.pdf')

How can I use BibTeX citations from Leo?

When using LaTeX and BibTeX, I would like to use inside of Leo a kind of LaTeX-inline-markup, that after generation of the RsT file through Sphinx as well as after running of “make latex”, generate a LaTeX file containing the citation call of the form cite{CITBook001} as described in a file *.bib. Is there a way to have Leo/Sphinx/RsT generate the inline raw latex syntax?

Use the docutils raw-data syntax. Examples:

.. role:: raw-role(raw)
  :format: html latex
.. raw:: latex
  \bibliographystyle{acm}
  \bibliography{myBibliography}

For more details, see this posting about BibTeX citations.

Markdown & Sphinx

How can I create markdown files?

Create your markdown files with @auto-md myfile.md.

This automatically converts headlines to section headings.

Optional: change @language md to @language rest. At present, syntax coloring for markdown is feeble.

How can I create a markdown table of contents?

The @button make-md-toc script in LeoDocs.leo writes a TOC to the console log.

Just select the @auto-md node and execute the script.

How can I use Markdown with Sphinx?

An open issue discusses various possibilities.

Scripting & Testing

How can I create buttons with dropdown menus?

The code that handles the rclick menu is in the QtIconBarClass class in qt_frame.py.

Show that the top-level button contains structure, do this:

@string mod_scripting_subtext = ▾

An alternative: ▼ U=25BC: Black Down-Pointing Triangle.

It’s reasonable to have the top-level button just be a placeholder for subsidiary @rclick nodes. To do that without getting a warning when clicking the top-level button, set its script to “empty string”.

How can I make commonly-used scripts widely accessible?

Put @command nodes as children of an @commands node in myLeoSettings.leo. This makes the @command nodes available to all opened .leo files.

Using @command rather than @button means that there is never any need to disable scripts. There is no need for @button. To see the list of your @command nodes, type:

<alt-x>@c<tab>

Similarly to see the list of your @button nodes, type:

<alt-x>@b<tab>

How can I organize large docstrings?

Start your file with:

'''
<< docstring >>
'''

The << docstring >> section can just contain:

@language rest # or md
@wrap
@others

This allows the “interior” of the docstring to be colored using rST (or markdown). The children of the << docstring >> node form the actual docstring. No section names are required!

This pattern organizes large docstrings in a Leonine way. The only drawback is that the actual external file contains sentinel lines separating the parts of the docstring. In practice, it’s no big deal, especially if each child starts with a blank line.

How can I run code in an external process?

g.execute_shell_commands executes one or more commands in a separate process using subprocess.popen. Commands not preceded by ‘&’ run to completion before the next command is run. See the scripting miscellany for more details.

How can I run scripts in languages other than python?

The execute-general-script command invokes an external language processor on an script file as follows:

• If c.p is any kind of @<file> node, the script file is the corresponding external file. Otherwise, the script file is a temp file.

• The @data exec-script-commands setting tells how to invoke the appropriate language processor. See the setting for more details.

• The @data exec-script-patterns settings describes error messages so that Leo can create clickable links to errors. See the setting for more details.

• This command is a thin wrapper around the c.general_script_helper method. Scripts can call this method directly if desired.

How can I run pylint outside of Leo?

Leo’s pylint command hangs Leo while it is running. The top-level leo-editor folder contains pylint-leo.py and pylint-leo-rc.txt. To run pylint outside of Leo, create a .bat or .sh file to run leo-editor/pylint-leo.py. On Windows, I use this pylint.bat file:

python2 c:\leo.repo\leo-editor\pylint-leo.py ^
rc=c:\leo.repo\leo-editor\leo\test\pylint-leo-rc.txt %*

The -h option produces this:

Usage: pylint-leo.py [options]

Options:
  -h, --help   show this help message and exit
  -a           all
  -c           core
  -e           external
  -f FILENAME  filename, relative to leo folder
  -g           gui plugins
  -m           modes
  -p           plugins
  -s           silent
  -u           user commands
  -v           report pylint version

My typical usage is pylint -a -s

How can I test settings easily?

Use .leo files to test settings rather than to contain data. These files would typically contain just an @settings tree, and one or two nodes illustrating their effect. Opening such files limits the effects of experimental/non-standard/risky settings. This is a great tip to know.

For example, the files leo10pt.leo, leo12pt.leo, leo14-12pt.leo and leo14pt.leo in the leo/config folder make it easy to compare different font settings.

As another example, when starting the vim-mode project I created a .leo file containing @bool vim-mode = True. By opening this file I test vim mode without interfering with my normal work flow.

How can I use setuptools instead of .bat files?

File under things-I-didn’t-know-but-should-have:

Instead of creating batch files all over the place to fire up python programs, and then having to cope with annoying “Terminate batch job (Y/N)?” with Ctrl-C/Break you can ask python setuptools to create an .exe in the PythonScripts folder.

in same folder as foo.py create setup.py, populate like so:

from setuptools import setup

setup(
    name='Foo for you',
    version='0.3',
    py_modules=['foo'],
    entry_points='''
        [console_scripts]
        foo = foo
        '''
    )

Then run “pip –editable install . “ in the same folder. Foo.exe will be created in C:pythonxxScripts. As long as that folder is in path you can use foo like any other command line program. Furthermore the “editable” parameter means we can continue to edit and change foo.py and the changes are always live.

Yeah! No more “pushd ..pathtodatafolder && python ..pathtocodefoo.py –do-stuff-here …” for me. :)

How can scripts call functions from Leo’s core?

Leo executes scripts with c and g predefined.

g is the leo.core.leoGlobal. Use g to access any function or class in leo/core/leoGlobals.py:

g.app                   A LeoApp instance.
g.app.gui               A LeoGui instance.
g.app.pluginsController A LeoPluginsController instance.
g.app.*                 Leo's global variables.

c is the Commander object for the present outline. Commander objects define subcommanders corresponding to files in leo/core and leo/commands:

# in leo/core...
c.atFileCommands
c.chapterController
c.fileCommands
c.findCommands
c.importCommands
c.keyHandler = c.k
c.persistenceController
c.printingController
c.rstCommands
c.shadowController
c.tangleCommands
c.testManager
c.vimCommands

# In leo/commands...
c.abbrevCommands
c.controlCommands
c.convertCommands
c.debugCommands
c.editCommands
c.editFileCommands
c.gotoCommands
c.helpCommands
c.keyHandlerCommands
c.killBufferCommands
c.rectangleCommands
c.spellCommands

Scripts can gain access to all of the code in these files via these subcommanders. For example, c.k is an instance of the LeoKeys class in leo/core/leoKeys.py.

How do I choose between @others and section references?

Use @others unless the contents of a node must appear in a certain spot, or in a certain order. For examples, most of Leo’s source files start like this:

@first # -*- coding: utf-8 -*-
<< imports >>
@others

The << imports >> section reference ensures that imports appear first. Another example:

@first # -*- coding: utf-8 -*-
<< imports >>
<< base classes >>
@others

This ensures that base classes are defined before their subclasses.

How to use leo to make mathematical notes?

If I want to use leo to make mathematical notes, how can I type in some special mathematical symbols? Or is there a good way to make mathematical notes using leo?

===== Terry

I use itex2MML with reStructuredText. So within Leo you’re looking at LaTeX math markup, and you get outputs in PDF and XHTML, with MathML in the latter.

===== Jose

I’ve been doing this for about a year now. I use the math docutils directive. A custom .XCompose file (for example: https://github.com/kragen/xcompose) also helps.

===== Terry

I think math was added to docutils after I started using itex2mml, neater to use docutils built in math now I think.

Although having said that, playing with docutils math a bit suggests itex2mml gives more complete support for both MathML and perhaps LaTeX math (with the PDF target).

===== Jose

Terry, your setup is probably more flexible, but I haven’t had any problems with docutils math. It seems to support all the syntax that I’ve found necessary.

I forgot to mention that the viewrendered plug-in doesn’t display math correctly. I’m not sure what the problem is, I remember trying to figure it out a while back, but I never got anywhere. It’s not really a big problem though, I have scripts to compile nodes to html/pdfs and open them in firefox/pdf reader; math works fine that way.

===== Offray

Is not properly Leo, but is python related, tailored for math and with a web interface and has leo bindings, check IPython: http://ipython.org/

I’m using it for all my math related writing and I think that point the future of interactive writing in Python. I dream of a body pane on leo with the features of the python qt console.

What is an easy way to profile code?

I had a need to figure out why a part of some python code I had written was taking too long. I pulled the code into Leo and the relevant part of the outline looked something like this:

+ Main module
-- Generate cryptographic key
-- Hashing algorithm

etc. So I cloned just the segment I wanted to profile and pulled it under a new section:

+ Main module
-- [clone] Generate cryptographic key
-- Hashing algorithm

+ Profiling Experiment
-- [clone] Generate cryptographic key

And in the body of the “Profiling experiment”, I used this code:

code_under_here = """
@others
"""

from timeit import Timer
t = Timer("print my_key_generator()", code_under_here)
print t.timeit(number = 10)

And then I hit Control-B to execute the Profiling Experiment body. This let me make adjustments to the code in the clone body and keep hitting Control-B to execute the code with the timeit module to see immediately if what I had done was making a difference.

The great thing about this was that I just used the Leo @others construct to create a wrapper around the code and did not need to litter my code with debug or profiling statements.—Kayvan

Trouble shooting

Error messages from the rst3 plugin aren’t helpful. What can I do?

For the most part, docutils does a good job of reporting errors. docutils prints a message to the console and inserts an unmistakable error message in the generated .html file. Important: On Windows it is helpful to run Leo in a console.

However, in some cases, docutils crashes instead of properly reporting the problem. There are several workarounds:

1. The crashes I have seen arise from the following bug in docutils. Hyperlinks in image:: markup must be lower case. This will work:

   .. .. |back| image:: arrow_lt.gif
       :target: faq_
   

   This will crash:

   .. .. |back| image:: arrow_lt.gif
       :target: FAQ_
   

   So avoid this crash by making sure to use lower case targets in ‘:target:’ markup.

2. You can change the docutils source slightly so that it prints a traceback when it crashes. (The rst3 plugin should be able to do this, but I haven’t figured out how yet.) It’s easy enough to do this:

• Find the file core.py in top-level docutils folder. Typically this folder will be in Python’s site-packages folder.

• Open core.py in some editor other than Leo.

• Find the method called report_Exceptions.

• Insert the following lines at the very start of this method:

  print 'EKR: added traceback'
  import traceback ; traceback.print_exc()
  

This will cause a traceback whenever docutils crashes. I have found that such tracebacks are generally enough to locate the general area of the problem. Note: These tracebacks go to the console window, so you should run Leo in a console.

3. As a last resort, you can isolate syntax errors by reducing your input files until they work again, then adding sections until you get a crash. This is easy enough to do (when using the rst3 plugin) by change a headline ‘x’ to @rst-ignore-tree x.

How can I move Leo’s window back on screen?

Leo is starting on one of the external monitors and I have no way to move it back to my laptop screen.

This has happened to me on Windows for as long as I can remember, mid 1990s and Windows 3. It’s rare, but I don’t think a year has gone by where it hasn’t occurred to me. At any rate, the most reliable and portable solution I’ve come across is:

• Press [Alt]-[Tab] until the invisible program has focus.

• Press [Alt]-[spacebar] to bring up window controls (Move, Size, Min, Max, Close).

• Press [M] to activate Move. A dotted or thin gray outline of window shape should appear.

• Press arrow cursor keys to move the outline centrally on active screen. (usually right- and down-arrow)

• Press [enter] when it’s moved on-screen enough to nab the Title bar with the mouse cursor.

How can I run Leo from a console window?

Leo (and other programs) often send more detailed error messages to stderr, the output stream that goes to the console window. In Linux and MacOS environments, python programs normally execute with the console window visible. On Windows, can run Leo with the console window visible by associating .leo files with python.exe not pythonw.exe.

How can I use Python’s pdb debugger with Leo?

Just run Leo in a console. At the point you want to drop into the debugger, execute this line:

g.pdb()

All output from pdb goes to stdout, which is the console window. It would be good to create a subclass of pdb.Pdb that uses Leo’s log pane rather than a console window, but I haven’t done that. It could be done easily enough in a plugin…

Important: I recommend using g.trace instead of pdb. For example:

g.trace(x)

prints the name of the function or method containing the trace, and the value of x. g.callers is often useful in combination with g.trace. g.callers(5) returns the last 5 entries of the call stack. For example:

g.trace(x,g.callers(5))

Used this way, g.trace shows you patterns that will be invisible using pdb.

How do I get help?

All questions are welcome at http://groups.google.com/group/leo-editor

How do I make Ctrl-Shift-0 work on Windows 8 or 10?

This key is normally bound to delete-comments. It is annoying not to have it work.

The only sure workaround is make other key bindings for add-comments and delete-comments. I suggest Ctrl-[ and Ctrl-].

At one time I thought the following might work, but it appears that it doesn’t:

1. In the control panel, click Language. This brings up the “Language” panel.

2. Choose “Advanced Settings” in the left area. This brings up the “Advanced Settings” panel.

3. Choose “Change language bar hot keys” in the left area. This brings up the “Text Services & Input Language” panel.

4. You will see Shift-Ctrl-0 as the binding for “Between input languages”.

   Select that item and click the “Change Key Sequence” button. This brings up the “Change Key Sequence” panel.

5. Set both radio buttons to “Not Assigned” and click OK.

How do I report bugs?

Please consider asking for help at http://groups.google.com/group/leo-editor before filing bug reports.

Please report bugs at http://bugs.launchpad.net/leo-editor

When reporting a bug, please include all of the following:

• The version of Leo used.

• The version of Python used.

• The platform or platforms used: Linux, Windows, MacOS.

• A clear description of the problem.

• Information sufficient to recreate the problem.

It’s polite to make the bug report self contained, so that six weeks later somebody will be able to understand the report as it stands.

I am having trouble installing Leo on MacOS. What should I do?

Installing PyQt on MacOS using:

brew install qt sip pyqt

may not always work. In that case, you will see something like this when running Leo:

Traceback (most recent call last):
File "launchLeo.py", line 8, in
leo.core.runLeo.run()
[Snip]
File "/Users/your-name/git/leo-editor/leo/plugins/qt_text.py",
line 434, in class LeoLineTextWidget(QtWidgets.QFrame):
AttributeError: 'NoneType' object has no attribute 'QFrame'

You can verify that PyQt has not been installed by setting the trace switch to True in leoQt.py. This will trace the import commands related to Qt and tell you exactly what is happening.

One Leo user gives this advice:

For anyone with similar problem the homebrew instruction for adding PyQT to the import path are wrong. Instead edit ~/.bash_profile and add this line:

export PATH="/usr/local/lib/python2.7/site-packages:${PATH}"

After this leo editor will open with using the default python installation provided by MacOS.

I can’t run the LeoBridge module outside of leo/core. What should I do?

Question and answer from plumloco.

Add the equivalent of:

import sys
leocore = "path/to/leo/core"
if leocore not in sys.path: sys.path.append(leocore)
import leo.core.leoBridge as leoBridge

at the head of each file that uses leoBridge.

The problem is not importing leoBridge itself but (if I use ‘from leo.core’) the importing of plugins, who get a different leoGlobals from leoBridge, without g.app etc, and so do not work if they rely on dynamic values in g.etc.

> Why can’t you simply add leo/core to sys.path in sitecustomize.py?

Putting leo/core on the python path as you suggest would put forty python modules in the global module namespace for all python programs when I want just one. Also, I have a safe working copy of leo and a cvs/testing version. I would wish to test any programs against the testing version while using the working version, but both /core directories can’t be exposed at the same time.

> Do you need plugins while running from the leoBridge?

Afraid so, at least the rst3 plugin. The solution I am using now is to place:

sys.modules['leoGlobals'] = leoGlobals

in leoBridge after import leo.core.leoGlobals as leoGlobals

This allows my scripts to be portable over the several computers/platforms I need to use them on, and makes testing scripts against multiple leo versions easy. It does mean that my scripts are not portable to other leo users but that is not likely to be a problem.

I can’t write Imported files. What’s going on?

The import commands insert @ignore directives in the top-level node. Leo does this so that you won’t accidentally overwrite your files after importing them. Change the filename following @file (or @file) as desired, then remove the @ignore directive. Saving the outline will then create the external file.

My old .leo files won’t load using Leo 4.5 or later. What should I do?

In version 4.5, Leo changed to using a sax parser for .leo files. This can cause problems if your .leo file contains invalid characters. Bugs in previous versions of Leo permitted these bad characters to appear.

The sax parser complains that these characters are not valid in .xml files. Remove these invalid characters as follows:

1. run Leo in a console, and load the .leo file. Near the bottom of the error message you will see a line like:

   SAXParseException: <unknown>:123:25: not well-formed (invalid token)
   

This line reports a bad character at character 25 of line 123.

2. Open the .leo file in an external editor. The Scite editor, http://www.scintilla.org/SciTE.html, is a good choice because it clearly shows non-printing characters. Remove the invalid character, save the .leo file.

Repeat steps 1 and 2 until all invalid characters are gone.

Nothing (or almost nothing) happens when I start Leo. What should I do?

Missing modules can cause installation problems. If the installer doesn’t work (or puts up a dialog containing no text), you may install Leo from the .zip file as described at How to install Leo on Windows. However you are installing Leo, be sure to run Leo in a console. because as a last resort Leo prints error messages to the console.

Running Python setup.py install from the leo directory doesn’t work. Why not?

Leo’s setup.py script is intended only to create source distributions. It can’t be used to install Leo because Leo is not a Python package.

The new Python decorator syntax causes problems. What can I do?

This syntax file hack works well enough to work with Leo ‘@’ markup:

syn region leoComment start="^@\\s*" end="^@c\\s*$"
syn match   pythonDecorator "@\\S\\S+" display nextgroup=pythonFunction skipwhite

Themes aren’t working for me. What should I do?

1. The directory leo-editor/leo/themes contains various theme files. You can load these files from the File:Open Outline menu.

Opening a theme outline automatically loads the theme. Keep opening outlines until you find one you like.

2. Close all of the theme files.

3. Copy the theme file you chose from leo-editor/leo/themes to ~/.leo/themes (you will have to create the themes folder here) and rename it something like myTheme.leo. Note that the folder is ~/.leo, not ~.

4. Open your myLeoSettings.leo file.

Add the following to the headline of a new node as a child of your @settings node: @string theme-name = myTheme.leo

5. Save the file and restart Leo.

You should now be using myTheme.leo. You can load myTheme.leo from Leo. The font sizing and colors are under Theme Settings in the tree.

Why didn’t Leo update my @clean outline as expected?

The update algorithm guarantees only that writing an updated @clean outline will generate the updated public file. Ambiguous lines could be placed either at the end of one node or the beginning of the following nodes. The update algorithm guesses that such lines should be placed at the end of the previous node.

Happily, guesses are not serious. Once you move an ambiguous node and save the Leo file, the update algorithm will not have to guess where the line belongs the next time Leo reads the @clean files.

Why do Qt windows disappear in my scripts?

@pagewidth 75

17. When I run the following script I see a window appear and then immediately disappear:

    from leo.core.leoQt import QtWidgets, QtCore
    w = QtWidgets.QWidget()
    w.resize(250, 150)
    w.move(300, 300)
    w.setWindowTitle('Simple test')
    w.show()
    

What’s going on?

1. When the script exits the sole reference to the window, w, ceases to exist, so the window is destroyed (garbage collected). To keep the window open, add the following code as the last line to keep the reference alive:

   g.app.scriptsDict['my-script_w'] = w
   

This reference will persist until the next time you run the execute-script. If you want something even more permanent, you can do something like:

g.app.my_script_w = w

Why isn’t the Spell tab showing?

Leo will show the Spell tab if:

1. The pyenchant spell checker has been installed or,

2. Leo finds a main spelling dictionary at ~/.leo/main_spelling_dict.txt. In this case, Leo uses a pure-python spell checker.

So if the Spell tab is not visible do the following:

• Download main_spelling_dict.zip from https://sourceforge.net/projects/leo/files/Miscellaneous/

• Unzip this file to ~/.leo/main_spelling_dict.txt.

The show-spell-info command tells what spell checker is in effect and the location of the main and user spell dictionaries.

Unicode

I can not enter non-ascii characters. What can I do?

Set @bool ignore_unbound_non_ascii_keys = False in LeoSettings.leo or myLeoSettings.leo.

Some characters in external files look funny. What can I do?

Internally, Leo represents all strings as unicode. Leo translates from a particular encoding to Unicode when reading .leo files or external files. Leo translates from Unicode to a particular encoding when writing external files. You may see strange looking characters if your text editor is expecting a different encoding. The encoding used in any external file is shown in the #@+leo sentinel line like this:

#@+leo-encoding=iso-8859-1.

Exception: the encoding is UTF-8 if no -encoding= field exists. You can also use the @encoding directive to set the encoding for individual external files. If no @encoding directive is in effect, Leo uses the following settings to translate to and from unicode:

default_derived_file_encoding

The encoding used for external files if no @encoding directive is in effect. This setting also controls the encoding of files that Leo writes. The default is UTF-8 (case not important).

new_leo_file_encoding

The encoding specified in the following line of new .leo files:

<?xml version="1.0" encoding="UTF-8">

The default is UTF-8 (upper case for compatibility for old versions of Leo).

I get weird results when defining unicode strings in scripts. What is going on?

Add the following as the very first line of your scripts:

@first # -*- coding: utf-8 -*-

Without this line, constructs such as:

u = u'a-(2 unicode characters here)-z'
u = 'a-(2 unicode characters here)-z'

will not work when executed with Leo’s execute script command. Indeed, the Execute Script command creates the script by writing the tree containing the script to a string. This is done using Leo’s write logic, and this logic converts the unicode input to a utf-8 encoded string. So all non-ascii characters get converted to their equivalent in the utf-8 encoding. Call these encoding <e1> and <e2>. In effect the script becomes:

u = u'a-<e1>-<e2>-z'
u = 'a-<e2>-<e>-z'

which is certainly not what the script writer intended! Rather than defining strings using actual characters, Instead, one should use the equivalent escape sequences. For example:

u = u'a-\\u0233-\\u8ce2-z'
u = 'a-\\u0233-\\u8ce2-z'

Some characters are garbled when importing files. What can I do?

The encoding used in the file being imported doesn’t match the encoding in effect for Leo. Use the @encoding directive in an ancestor of the node selected when doing the Import command to specify the encoding of file to be imported.

Python’s print statement shows ‘byte hash’ for unicode characters. What can I do?

First, you must change Python’s default encoding to something other than ‘ascii’. To do this, put the following in your sitecustomize.py file in Python’s Lib folder:

import sys
sys.setdefaultencoding('utf-8') # 'iso-8859-1' is another choice.

You must restart Python after doing this: sys.setdefaultencoding can not be called after Python starts up.

Leo’s g.es_print and g.pr functions attempts to convert incoming arguments to unicode using the default encoding. For example, the following Leo script shows various ways of printing La Peña properly:

@first # -*- coding: utf-8 -*-

import sys
e = sys.getdefaultencoding()
print 'encoding',e
table = (
    'La Peña',
    unicode('La Peña','utf-8'),
    u'La Peña',
    u'La Pe\\xf1a',
)

for s in table:
    print type(s)
    g.es_print('g.es_print',s)
    if type(s) != type(u'a'):
        s = unicode(s,e)
    print 'print     ',s
    print 'repr(s)   ',repr(s)

For still more details, see: http://www.diveintopython.org/xml_processing/unicode.html

Vim

How can I use Leo’s bridge in vim?

This script appends the outline headlines, indented, to the current vim buffer:

import leo.core.leoBridge as leoBridge
import vim

controller = leoBridge.controller(
    gui='nullGui',
    loadPlugins=True,  # True: attempt to load plugins.
    readSettings=True,  # True: read standard settings files.
    silent=True,  # True: don't print signon messages.
    verbose=False,  # True: print informational messages.
)
g = controller.globals()
c = controller.openLeoFile("/home/tbrown/.leo/del.leo")

def dent(node, result, level=0):
    result.append('  ' * level + node.h)
    for child in node.children:
        dent(child, result, level + 1)
    return result

result = []
dent(c.hiddenRootNode, result)
vim.current.buffer[-1:] = result

It can be invoked with:

:py import leodent

assuming it’s in a file leodent.py and on the Python path.

Work flow

How can I organize data so I can find stuff later?

When organizing data into nodes, every item should clearly belong to exactly one top-level category. In other words, avoid top-level aggregate categories.

For example, the following are poor top-level categories. They are poor because any item in them could be placed in a more explicit category:

• Contrib

• Developing Leo

• Important

• Maybe

• Others

• Prototype

• Recent

• Won’t do/Can’t do

We all have had bad experiences with the dreaded “Others” category. The Aha! is that all aggregate categories are just as bad as “Others”.

Note: I have been talking only about top-level categories. Within a single category aggregate categories may be useful. However, when possible I prefer to mark items rather than create subcategories. For example, * now marks all “Important” items in leoToDo.txt and scripts.leo. This makes it easy to find important items in a particular category. To find all important items one could do a regex search for ^\* in headlines.

How can I restore focus without using the mouse

It sometimes happens that the focus gets left in a Leo widget that doesn’t support Leo’s key bindings. You would think that you would have to use the mouse to click in, say, the body pane so that you can use Leo’s key bindings again.

But you don’t have to do that. Instead, use Alt-tab once to change away from Leo, and then use Alt-tab again to change back to Leo. When you do this, Leo puts focus in the body pane and you are all set.

How can I see two nodes at once?

By Rich Ries. I often rework C code that’s already been “Leo-ized”–the first pass was quick and dirty to get it going. When I do subsequent passes, I wind up with subnodes that are out of order with the sequence found in the main node. It’s not a big deal, but I like ‘em ordered. With just one editor pane, clicking on the node to move would switch focus to that node. I’d then need to re-focus on the main node. A minor nuisance, but it does slow you down.

My solution is to open a second editor with its focus on the main node. Switch to the other editor, and, referring to the first editor pane, move the nodes as you like. The second editor’s pane will change focus to the node you’re moving, but the first editor will stay focused on the main node. It’s a lot easier to do than to describe!

How can I use Leo cooperatively without sentinels?

Most people will find using @clean trees to be most useful. Use @auto-rst, @auto-vimoutline or @auto-org when using rST, vimoutline or Emacs org mode files.

How can I use the GTD workflow in Leo?

GTD (Getting Things Done) http://www.amazon.com/Getting-Things-Done-Stress-Free-Productivity/dp/0142000280 is, by far, the best productivity book I have ever read. Many aspects of Leo are idea for putting GTD into practice.

Here is a surprisingly useful workflow tip related to GTD.

Ideas often “intrude” when I am busy with something else. When that happens, I create a top-level node of the form:

** description of idea

Now I can continue what I was doing! This is such a simple idea, but it’s really really important: it means I never have to put off getting my ideas into Leo. The “**” draws my attention to the new to-do item. Later, when I am not fully immersed in the previous task, I can put the “**” node somewhere else.

It’s super important to deal with new ideas instantly but without greatly interrupting the task at hand. Creating “**” nodes does that. This new workflow has been a big improvement to my GTD practice.