Swig, python and output strings

Question

I am using Swig to wrap a C interface that looks like this:

int dosomething(char **str);

where str is an output string. For example, from C its called like this:

char *str= NULL;
int val= dosomething(&str);
   ...
free(str);

In Python, I'd like to be able to call it like this:

val,str = dosomething()

However, python keeps reporting

TypeError: dosomething() takes exactly 1 arguments (0 given)

I've tried using OUTPUT in a typemap, but to no avail. Any ideas?

may I suggest you try ctypes? Its much faster to port C functions this way — damir
– damir, Commented Dec 8, 2010 at 23:49
Unfortunately, ctypes is python-only. I'm using swig because I need to wrap for many different languages (Java, etc). — paleozogt
– paleozogt, Commented Dec 8, 2010 at 23:56

Mark Tolonen · Accepted Answer · 2010-12-09 05:47:55Z

1

Try this typemap (I'm using SWIG 2.0.0):

%include <cstring.i>
%cstring_output_allocate(char **str, free(*$1));

Documentation: cstring.i

answered Dec 9, 2010 at 5:47

Mark Tolonen

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Comments

salezica · Accepted Answer · 2010-12-09 00:34:48Z

0

Why not use it normally, passing a parameter, and wrap it inside python to return a tuple?

answered Dec 9, 2010 at 0:34

salezica

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