ctypes & strings

Aaron Brady castironpi at gmail.com
Sun Dec 28 01:06:23 CET 2008


On Dec 27, 2:03 pm, "Gabriel Genellina" <gagsl-... at yahoo.com.ar>
wrote:
> En Sat, 27 Dec 2008 10:54:32 -0200, Hendrik van Rooyen  
> <m... at microcorp.co.za> escribió:
>
> > The c routine will actually break Python's normal string
> > immmutability and give you back a changed ins.
>
> ...so don't do that!
> If you require a mutable string to pass to C functions, use  
> ctypes.create_string_buffer()
>
> > It is in general not a good idea to change the passed string
> > like I am doing - but you wanted to know how
> > to pass a python string, and the outs example should get
> > you going - a string is an array of characters in c...
>
> Hmmm, I don't think posting a potentially harmful example is actually a  
> good idea...
>
> --
> Gabriel Genellina

One alternative would be to return a pair of Python strings.  You
might want to wrap the C function you have already in another one,
which allocates buffers and creates Python objects.

Hendrik is right, though.  The ctypes module allows us to break string
immutability within Python code.



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