[Python-Dev] how important is setting co_filename for a module being imported to what __file__ is set to?

[Brett Cannon]

On Mon, Aug 31, 2009 at 12:27, Antoine Pitrou<solipsis at pitrou.net> wrote:
> Brett Cannon <brett <at> python.org> writes:
>>
>> I will plan to take this approach then;
>> http://bugs.python.org/issue6811 will track all of this. Since this is
>> a 3.2 thing I am not going to rush to implement this.
>
> I still don't understand what the point is of this complicated approach (adding
> an argument to marshal.load()) compared to the simple and obvious approach
> (making co_filename mutable).

If we add the argument to marshal.load* we can eventually drop the
file location string from marshal data entirely by requiring people to
specify the filename to use when the code object is created. Making
co_filename mutable simply doesn't allow for this case unless we
decide a default value should be used instead.

> Besides, the latter would let you code the recursive renaming algorithm in
> Python, which is the whole point of importlib (rewriting most code in Python),
> isn't it?

Sure, but I am not about to re-implement marshal in pure Python just
because importlib uses it.

-Brett