Leo – Python based IDE, Outliner and PIM

Last Updated on September 22, 2023

Leo (Leonine Editor with Outlines) is an open source text editor, outliner and IDE that features clones (virtual copies of outline nodes) as its central tool of organization, navigation, customization and scripts.

This IDE is written in Python and can be extended with plugins written in Python. The GUI uses the Qt toolkit.

It’s very mature software with development spanning more than 20 years.

Features include:

• A fully-featured IDE, with many features inspired by Emacs.
• Syntax highlighting is provided for many different programming languages.
• An outliner. Everything in Leo is an outline. It provides commands to insert, delete, move, hoist, promote and demote nodes. Clones are a unique feature of Leo.
  • Directives control how Leo works.
  • @file and @clean nodes create external files.
  • myLeoSettings.leo specifies your personal settings.
  • Plugins extend Leo. @enabled-plugins settings nodes enable plugins.
  • Easy-to-use scripting API, giving full access to all data in the outline.
  • @button and @command nodes define scripts that can be applied to other nodes.
  • @test nodes create unit tests.
  • Alt-1 enables autocompletion.
• A data manager, data manager and personal information manager.
• A powerful scripting environment.
• A tool for organizing and studying computer code.
• Extensible via a simple plugin architecture.
• A tool that works well with IPython, Vim and Emacs.
• Support for Jupyter (.ipynb) files.
• Plugins – give Leo new commands, modify how existing commands work, or change any other aspect of the software’s look and feel. There are dozens of plugins available including:
  • bookmarks.py manages and shows bookmarks.
  • contextmenu.py shows a context menu when you right-click a headline.
  • mod_scripting.py supports @button and @command nodes.
  • quicksearch.py adds Nav tab for searching.
  • todo.py provides to-do list and simple project-management capabilities.
  • valuespace.py adds outline-oriented spreadsheet capabilities.
  • viewrendered.py creates the rendering pane and renders content in it.
• Execute Python unit test from within Leo outlines.
• Written in 100% pure Python.
• Completely integrates Python scripting and outlines.
• Highly configurable.

Website: leo-editor.github.io
Support: Documentation, GitHub Code Repository, Mailing List
Developer: Edward K. Ream and many contributors
License: MIT License

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