[capi-sig] C functions that modify their arguments.

[M.-A. Lemburg]

Wendell Nichols wrote:
> I have a library that I want to wrap for Python (as part of an exercise to learn Python, and provide
> some public good at the same time :)  The library is proprietary and I can't change it.  Many of its
> functions modify a pointer provided via an address arg.  Can python deal with functions that modify
> their arguments?  If so (generally) how?
> 
> If there is no formalised way I'm may have to consider registering some sort of callback to alter
> the argument from within C... kind of awkward but since I'm code generating all the C so long as I
> have a workable approach it doesn't matter how much code it takes :)

You mean: The C functions write data into buffers your Python wrapper
has to provide ?

That's possible, but you'll have to manage memory allocation in your
wrapper. Alternatively, you could copy the data into Python objects
to have Python take over memory management.

PS: You might want to consider using a wrapper generator such as SWIG,
Boost or sip to help you with the wrapping of the library. They typically
take care of all this.

-- 
Marc-Andre Lemburg
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