On Mon Feb 23 2015 at 1:34:03 PM Daniel Holth <dholth@gmail.com> wrote:

On Mon, Feb 23, 2015 at 1:16 PM, Brett Cannon <brett@python.org> wrote:
> Overall I like this and don't see any reason not to accept it, so +1. I do
> have a couple comments/questions on the module API, though.
>
> On Mon Feb 23 2015 at 12:45:28 PM Paul Moore <p.f.moore@gmail.com> wrote:
>>
>> <SNIP>
>>
>>
>> ``set_interpreter(archive, new_archive, interpreter=None)``
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>
>> Modifies the *archive*'s shebang line to contain the specified
>> interpreter, and writes the updated archive to *new_archive*. If the
>> *interpreter* is ``None``, removes the shebang line.
>
>
> Should new_archive default to None to allow for in-place editing?
>
> -Brett

That would be cool but more work. Unless the length of the new shebang
is <= the old one, the zip file contents have to be moved out of the
way.

Couldn't you just keep it in memory as bytes and then write directly over the file? I realize that's a bit wasteful memory-wise but it is possible. The docs could mention the memory cost is something to watch out for when doing an in-place replacement. Heck the code could even make it an io.BytesIO instance so the rest of the code doesn't have to care about this special case.