ANN: Leo 4.3-a1 released

Edward K. Ream edreamleo at
Mon Jan 24 17:03:23 CET 2005

Leo 4.3 alpha 1 is now available at

Leo 4.3 is the culmination of more than four months of work.  In spite
of its alpha status, I recommend Leo 4.3a1 over any 4.2 release.

The defining features of Leo 4.3:
1. Leo now stores options in @settings trees, that is, outlines whose
headline is '@settings'. When opening a .leo file, Leo looks for
@settings trees not only in the outline being opened but also in
various leoSettings.leo files.

The key design goal of @settings trees was that Leo's user options
must be infinitely flexible. That goal has been accomplished. Indeed,
users can create arbitrarily complex user options with @settings
trees. Leo settings outlines are, in fact, infinitely more flexible
and powerful than any scheme based on flat text. Readers of Python's
configParser shootout take note.

2. The Preferences command temporarily replaces the outline pane with
an outline showing all the @settings trees in effect. The Preferences
command also replaces the body pane with a "settings pane". This
settings pane allows you to change the settings selected in the
outline pane using standard gui widgets. The settings pane is
dynamically created from nodes in the settings tree; it is as
extensible as the @settings tree itself.

3. Leo's read/write code in has been rewritten to support
user-defined tangling and untangling. This is a major cleanup of
Leo's core.

4. Leo now boasts a wonderful new Plugins Manager plugin. This plugin
enables and disables plugins automatically. You never have to mess
with pluginsManager.txt again. This plugin also tells you everything
you need to know about each plugin. Finally, this plugin also lets you
download plugins from Leo's cvs site.

5. You can install third-party extensions in Leo's extensions
directory. Leo will attempt to import such extensions from the
extensions directory if normal imports fail.

As usual, version 4.3 contains many other improvements and bug fixes.

What people are saying about Leo
"I am using Leo since a few weeks and I brim over with enthusiasm for
it. I think it is the most amazing software since the invention of the
spreadsheet." -- juergen_r

"We who use Leo know that it is a breakthrough tool and a whole new
way of writing code."  -- Joe Orr

"I am a huge fan of Leo. I think it's quite possibly the most
revolutionary programming tool I have ever used and it (along with the
Python language) has utterly changed my view of programming (indeed of
writing) forever."  -- Shakeeb Alireza

"Thank you very much for Leo. I think my way of working with data will
change forever...I am certain [Leo] will be a revolution. The
revolution is as important as the change from sequential linear
organization of a book into a web-like hyperlinked pages. The main
concept that impress me is that the source listing isn't the main
focus any more. You focus on the non-linear, hierarchical, collapsible
outline of the source code."  -- Korakot Chaovavanich

"Leo is a quantum leap for me in terms of how many projects I can
manage and how much information I can find and organize and store in a
useful way."  -- Dan Winkler

"Wow, wow, and wow...I finally understand how to use clones and I
realized that this is exactly how I want to organize my information.
Multiple views on my data, fully interlinkable just like my thoughts."
-- Anon.

"A few years back I would have said Zope was #1 Python showcase, but I
agree 100% that Leo is tops now." -- Jason Cunliffe

"Leo is the most interesting Python project I know of...I see lots of
stuff posted on the Daily Python page, but I usually yawn and come
over to this forum to see what's cooking."  -- Anon

More quotes at:

What makes Leo special?
- Leo's outlines add a new dimension to programming.
- Leo shows you your code and data the way _you_ want to see them.
- Leo extends, completes and simplifies literate programming.
- Leo's script buttons bring scripts to data.

What is Leo?
- A programmer's editor, an outlining editor and a flexible browser.
- A literate programming tool, compatible with noweb and CWEB.
- A data organizer and project manager. Leo provides multiple views
   of projects within a single outline.
- Fully scriptable using Python. Leo saves its files in XML format.
- Portable. is 100% pure Python.
- Open Software, distributed under the Python License.

Leo requires Python 2.2.1 or above and tcl/tk 8.4 or above.
Leo works on Linux, Windows and MacOs X.


Edward K. Ream
January 25, 2005
Edward K. Ream   email:  edreamleo at
Leo: Literate Editor with Outlines

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