Terry Reedy <[EMAIL PROTECTED]> wrote:
> "Brian van den Broek" <[EMAIL PROTECTED]> wrote in message
> news:[EMAIL PROTECTED]
> > Is the right way to understand it in this vicinity:
>
> In the vicinity, but not quite exact
>
> >At compile time (by which I mean when the Python bytecode is built)
>
> Compile time is when the def statement is executed
I disagree: compile time is when the compiler is running (for example,
the compiler is the component which diagnoses syntax errors, while other
errors are diagnosed ``at runtime'').
Bytecode is built before def executes -- indeed it's built whether def
executes or not. Cfr:
>>> def f(wo):
... if wo:
... def g(): pass
...
>>> f.func_code.co_consts
(None, <code object g at 0x382a60, file "<stdin>", line 3>)
the 'def g' hasn't executed (yet?), but the bytecode is built (and
stored as the first constantvalue in f, save the ubiquitous None).
If the ``if wo: def ...'' construct was in a module being imported, the
mechanics would be similar -- although in this case I think you could
tell only if a syntax error was present in the def statement (I may be
wrong, but offhand I don't think the codeobject is saved in this case).
Or, try this one:
>>> c = compile('def x(): pass', '<string>', 'exec')
>>> c
<code object ? at 0x389420, file "<string>", line 1>
>>> c.co_consts
(<code object x at 0x3893e0, file "<string>", line 1>, None)
>>>
``compile time'' here is when the 'compile' built-in runs; and we can
see the code object ``x'' is already built even though the def has not
been executed yet.
Alex
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