[Python-Dev] towards a faster Python

[Brett C.]

Neil Schemenauer wrote:
> Hi guys,
> 
> With Guido's blessing, I just commited a change that takes a small step
> towards where we want to be, IMO.  Using __setattr__ on a module to
> create a global name that shadows a builtin name now raises a
> DeprecationWarning.  E.g.
> 
>     import fileinput
>     fileinput.open = 10 # <- warning will be raised
> 
> The goal is that the compiler should be able to determine the scope of a
> name at compile time.  Code like the above does not allow that and so
> non-local names must be searched for in both globals and builtins at run
> time.  

Spiffy.

> Unfortunately the warning is not bulletproof.  It's possible to
> modify the module dict directly and bypass the warning.  I'm not sure
> what to do about that. :-(
> 

Probably only way to deal with that would to come up with namespace 
dicts that can restrictions set on them?

> Eventually we might want to allow optimizations based on known builtin
> functions.  For example, code like
> 
>     for i in range(100000):
>         ...
> 
> could be rewritten to use an integer counter rather than creating a list
> and then iterating over it.  I'm not sure how much resistance there
> would be in the community to disallowing reassignment of builtin names
> though.  I don't think I've ever reassigned a builtin name so I think it
> would be worth it.
> 

I am personally fine with this since I too never assign to built-in 
names, but I can see people raising a stink over this citing that their 
freedoms are being encroached upon.  =)

> The compiler could also warn about references to non-existent names.
> That's a common error and would be helpful to developers.
> 

Isn't this getting into PyChecker's territory?

-Brett