[Python-Dev] towards a faster Python

[Guido van Rossum]

> 1. Extending builtins should still be possible like it is now.
> 
>     Of course, the extensions wouldn't take part in the optimizations
>     you have in mind, but they should still be found.

I'm not sure what you mean by "extending builtins", but if it is what
I think it is, I am strongly opposed.  The builtins should have fixed
capabilities (in a particular Python version).  If you want a function
that behaves just like a builtin but also can do something else, give
it a different name and import it explicitly, don't override the
existing entry in __builtin__.  If you have a new function that you
want to use in lots of code, resist the temptation to add it to the
__builtin__ module.  Zope did this e.g. with get_transaction() and the
net result was reader confusion and intractable dependencies on import
order.

> 2. What happens if a new Python version introduces new builtins
>     that are in use by some modules out there for other purposes ?

*** THIS IS NOT AFFECTED! ***

There is no proposal on the table to ban the use of identifiers known
to be built-ins for any purpose.  If a module defines a class,
function or variable that shadows a builtin name, that's fine, because
the parser has no problem detecting this situation.

The *only* thing being banned is insertion of a new name that shadows
a builtin from outside a module.

IOW:

  # module foo
  def open(): return ...

is fine, but

  import foo
  foo.open = 42

is not.

--Guido van Rossum (home page: http://www.python.org/~guido/)