[Python-Dev] 2.6 and 3.0 tasks

[Collin Winter]

On Sun, Mar 16, 2008 at 8:23 AM, Guido van Rossum <guido at python.org> wrote:
>  On Sun, Mar 16, 2008 at 9:42 AM, Christian Heimes <lists at cheimes.de> wrote:
......
>  > and add the fixers to 2to3
>
>  +1. I think quite a few changes have not had a fixer added. Again, I
>  think we should maintain a specific list of needed fixers; fixers can
>  easily be developed independently.

Neal and I are coming up with a list to feed tasks to interested PyCon
sprinters.

>  >  * Speed up 2to3. I suggested a GSoC task to improve and speed up 2to3
>  >  but it may be too late when we plan to ship out 3.0 in August.
>
>  While I know that some people are expecting to use a development model
>  that invokes 2to3 very frequently, I think this is at best a
>  nice-to-have. (I also don't see how it could be done, but maybe I'm
>  blind for the obvious, as the original author.)

The biggest win in terms of performance would be to reimplement the
pattern matching engine used by the fixers.: it by far dominates the
running time, taking 99+% of the runtime when I ran 2to3 over Twisted,
for example. The current design is a heavily-recursive system, and as
such bombs out when it encounters, e.g., files with a thousand
assignment statements in a row. I'd also like something more
expressive: the current DSL can't express recursive patterns.

Collin Winter