[C++-sig] Calling import() multiple times for the same module

[Robert Dailey]

On Fri, Oct 24, 2008 at 1:07 PM, Stefan Seefeld <seefeld at sympatico.ca>wrote:

> Robert Dailey wrote:
>
>> Hi,
>>
>> What happens if I do the following?
>>
>> using namespace boost::python;
>>
>> import( "__main__" ).attr( "new_global" ) = 40.0f;
>> import( "__main__" ).attr( "another_global" ) = 100.0f:
>>
>>
>> My main concern here is performance. I'm wondering if each call to
>> import() results in a disk query for the script in question and loads it
>> from there. I'm also wondering if the second import() above will simply
>> read from a memory cache or something.
>>
>
> As the above code is only a wrapper around the Python runtime, you are
> really asking about how Python handles repeated 'import' calls. I'm pretty
> sure importing a module while it is already imported will do (almost)
> nothing. However, I'm not sure whether a module is actually unloaded as soon
> as the last reference goes away (such as after the first line above is
> completed), so I can't give a definite answer.
>
> I'm sure you'll get better answers when asking on a Python forum directly.


I posted about this on the Python mailing list but I'm receiving no
responses :(
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