Compile time evaluation of dictionaries

[Steven D'Aprano]

On Thu, 10 Mar 2011 11:23:32 -0500, Gerald Britton wrote:

> Today I noticed that an expression like this:
> 
> "one:%(one)s two:%(two)s" % {"one": "is the loneliest number", "two":
> "can be as bad as one"}
> 
> could be evaluated at compile time, but is not:
[...]
> Any idea why Python works this way?  I see that, in 3.2, an optimization
> was done for sets (See "Optimizations" at
> http://docs.python.org/py3k/whatsnew/3.2.html) though I do not see
> anything similar for dictionaries.

Python is a language, what you are looking at is an implementation of 
that language. Although I have never used it myself, apparently Cesare Di 
Mauro's WPython does more constant folding optimizations than CPython. 
See pages 21-24 of 

http://wpython2.googlecode.com/files/Beyond%20Bytecode%20-%20A%20Wordcode-based%20Python.pdf



-- 
Steven