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Leo is Love

February 1, 2013
tags: leo, literate programming, text editor

Hello all.

Today I'm writing to evangelize my newest addiction, Leo.

Leo is a text editor, PIM tool, outliner, visual literate programming IDE, database, and way of life. Since discovering it a few days ago, I've started using it exclusively. In fact, this very article was written with it.

I thought I'd share a few tips on how to get it up and running on Windows systems, and then a few little snippets of fun that I've picked up along the way.

Installing Leo on Windows systems

Getting Leo running on Windows systems isn't as difficult as it seems. You do need a few things, though:

  1. Python 2.7, 32-bit. Available here. 64-bit Python does not work for PyEnchant, meaning that you won't have spellcheck if you go that route. Also, there isn't a 64-bit setuptools package at the moment, so installing docutils will be difficult. But Leo doesn't need much RAM, so this isn't a problem.

  2. PyQT for 32-bit Python 2.7. Available here.

  3. PyEnchant for Python 2.7. Available here.

  4. setuptools for Python 2.7. Available here.

  5. The latest Leo snapshot. Available here.

  6. Optional: create-leo.bat, available here.

Install Python, PyQT, PyEnchant, and setuptools, in that order.

Pretty straight forward. Just accept the defaults and continue.

Install pip and docutils

Open up a command prompt, and enter the following commands:

cd C:\Python27\Scripts
easy_install.exe pip
pip install docutils

Unzip the leo snapshot

Pick somewhere you'll remember it.

That's it. You can now run Leo by doubleclicking launchLeo.py. However, we can integrate it into the OS a bit more, making it much nicer to use.

Optional: run create-leo.bat

Copy create-leo.bat to your Leo directory (the one with launchLeo.py). Now open a command prompt, and do the following:

cd C:\path\to\leo
create-leo.bat "C:\Python27\python.exe" register

That will do 2 things: create some .bat files, and register the .leo file extension to open with Leo. You are free to move leo.bat and leoc.bat anywhere on your system... double-click them and Leo will run (leoc.bat keeps the console open). Sinde .leo was registered to open with Leo, you can double-click on any .leo file to open it in Leo, too.

Congratulations, you have Leo on your system.

Some Leo Tricks

Set up your myLeoSettings.leo file

Seriously, there's crazy power in this file. It allows you to change the way most of Leo works.

Me? Mine's pretty simple at the moment.

@settings
- Plugins
--- @enabled-plugins <- I've disabled the nav_qt.py
                        plugin, as I find it annoying
- Keyboard Shortcuts
--- @shortcuts MyKeybindings <- I've assigned `tab-cycle-previous` 
                                and `tab-cycle-next` to 
                                `ctrl+shift+tab` and `ctrl+tab`, 
                                respectively, as it mimics how 
                                Firefox and Chrome handle 
                                tab-switching

Make some @buttons with external script references

I wanted to make some @button nodes which would call a function with different parameters. Due to the way Leo scopes things, it wouldn't work to write the function in a separate script and reference it with a << script reference >> notation, as in a @file node -- it won't be expanded.

The solution, provided to me on the leo-editor Google group by the author of Leo himself, is brilliant.

Use exec to "inject" shared code into the namespace of the script being executed. This is a cute trick, but it doesn't seem to be in the faq. There are example of this trick in unitTest.leo: search for "@common".

Do the following:

A. Put the common code somewhere, say in a node called "@common code". Note that the node can be called anything: I use @common to draw they eye, but it's just my convention.

B. Start each script using the common code with::

exec(g.findTestScript(c,'@common code'))

g.findTestScript returns the expanded code of the entire subtree whose head is the node "common code". Thus, you can use @others and section references in the "common code" subtree! It's cute.

This translates into something like this:

Node `@common code`:
  def foo(bar):
    g.es("Hiya, %s!" % bar)

Node `@button george`:
  exec(g.findTestScript(c,'@common code'))
  foo('george')

Node `@button clem`:
  exec(g.findTestScript(c,'@common code'))
  foo('clem')

2 buttons calling 1 script, without code repetition! This is nice, and it shows the power that Leo has, by giving you the ability to access your entire document programmatically. Simply beautiful, in my book.

I've used what I've learned so far to begin creating a Leo workbook helpful for running tabletop RPGs. It's on Github if you're curious: gatesphere/rpg.leo.

Thanks for reading!

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