[Python-Dev] PEP 343 update (with statement context terminology)

[Guido van Rossum]

On 4/24/06, Aahz <aahz at pythoncraft.com> wrote:
> Let's go back to a pseudo-coded with statement:
>
>     with EXPRESSION [as NAME]:
>         BLOCK
>
> What happens while BLOCK is being executed?  Again, here's what I said
> originally:
>
>     EXPRESSION returns a value that the with statement uses to create a
>     context (a special kind of namespace).  The context is used to
>     execute the BLOCK.  The block might end normally, get terminated by
>     a break or return, or raise an exception. No matter which of those
>     things happens, the context contains code to clean up after the
>     block.

I strongly object to your use of the term "namespace" here. The with
statement does *not* create a new namespace. Using the term namespace
will only confuse people who understand what it means (in Python) --
we have the global namespace, the builtin namespace, the local
namespace, classes introduce a new namespace, etc. The with-statement
does *not* create a namespace in this sense -- there's no new place
where name lookup can take place. In particular, this code prints 42:

  x = 1
  with whatever(doesnt_matter):
      x = 42
  print x

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