parse-time optimizations

Michael Hudson mwh at python.net
Tue May 29 21:01:14 CEST 2001


jcm <grumble at usa.net> writes:

> Michael Hudson <mwh at python.net> wrote:
> 
> > Thing is, if you're writing code that benefits from constant folding -
> > WHY?  If your code contains things like:
> 
> >     "a" + "b"
> 
> > then you have bigger problems than Python's lack of optimizations...
> 
> The example "a" + "b" was, of course, an example.  Something like
> 
>   "some really long string (probably longer than this one) that I " +
>   "can't quite fit onto one line in good conscience"
> 
> would be more realistic.  

Well, there are other ways round that one; literal conatenation or
backslashing the newline.  

> There's also the case where code is generated by another tool.
> Somewhat relatedly, I've seen C macros that generate expressions
> like
> 
>   1 + 1 + 1 + 1 + 1 + 1 + 0
> 
> so there are instances where this sort of thing comes up.

True - but Python has no preprocessor so this is still fairly
unlikely.  I don't think that many people machine generate Python -
but I could be wrong.

I don't want to discourage anyone from implementing these
optimizations for Python - but the benefit/effort ratio is rather
small.

Cheers,
M.

-- 
  Academic politics is the most vicious and bitter form of politics,
  because the stakes are so low.                      -- Wallace Sayre



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