Friday, August 14, 2009

Announcing Leo 4.6.2 final

Leo 4.6.2 final is now available here. For more info, see Leo's web site.

The highlights of Leo 4.6
- Cached external files *greatly* reduces the time to load .leo files.
- Leo supports both the Tk and Qt gui interfaces.
- New --config, --file and --gui command-line options.
- Leo tests syntax of .py files when saving them.
- Leo can now open any kind of file into @edit nodes.
- @auto-rst nodes allow easy editing of reStructuredText files.
- Properties of commanders, positions and nodes simplify programming.
- Improved Leo's unit testing framework.
- Leo now requires Python 2.5 or later.

Saturday, August 1, 2009

Better Python logging

This is a response to

Back when Python's logging module was being designed, I asserted that there is a much better way to enable and disable logs than a linear sequence of logging levels. That proposal went nowhere, perhaps because people heard it as dismissing the whole notion of having a standard logging module.

In fact, though, it would be easy to graft a small extension on to Python's logging module that would make logging much more flexible. Here's how

1. Add another logging level, say 'custom'. When custom logging is in effect, log messages are generated if they match a **tracepoint name**. Such names are simply strings.

2. Add the following method to the logging module::

logging.custom("abc",'This a custom message logged when "abc" is enabled.')

3. Enable or disable custom tracepoint names with::



Each patten is a string, possibly containing wildcard characters '*' and '?', that matches zero or more tracepoint names. The enable/disable_custom methods simply add or delete entries in a **pattern database** of enable and disabled names.

When logging.custom(s,message) is executed, it searches the pattern database for a match with the string s. It prints the message to the log if a match is indeed found.

That's about it. It's easy to do, compatible with the present logging system, but much more flexible.

Many small tweaks to this scheme are possible, but I'll save those in case there is some real interest.

The Age of Entanglement

Here is a quote from the preface of "The Age of Entanglement", by Louisa Gilder,
one of the few books I have read lately from start to finish:

"Science rests of experiments," wrote Heisenberg, but "science is rooted in conversations."

Nothing could be further from the impression physics textbooks give to students. There, physics seems to be a perfect sculpture sitting in a vacuum-sealed case, as if brains, only tenuously connected to bodies, had given birth to insights fully formed...

Physics, in actuality, is a never-ending search made by human beings...The schoolbook simplifications obscure the crooked, strange and fascinating paths that stretch out from each idea, not only back into the past but onwards into the future...

Conversations are essential to science. But the off-the-cuff nature of conversation poses a difficulty. It is rare, even in these digital times, to have a complete transcript of every word spoken between two people on a given day, even if that conversation someday leads to a new understanding of the world. The result is that history books rarely have much of the to-and-fro of human interaction. Heisenberg's statement suggests that something is therefore lost.

Being part of the Python world via its many conversations is one of my life's great joys.