Python, SWIG and pointers

Nicolas Devillard ndev42 at
Fri Mar 10 10:56:19 CET 2000

I have a C library and I have to make bindings to
Python using SWIG. The problem I have is: how to
handle pointers to pointers?

If I have the following data struct in C:

typedef struct _OBJ_ {
} obj ;

And the associated constructor, used as:

obj * b ;
a = new_obj() ;

Then there are functions expecting a pointer to
a pointer to struct for modification, something like:


The SWIG-generated binding for new_obj() will
return an opaque object that is compatible with a
pointer to obj, but how do I pass it in Python
to modify_obj(), that is expecting a pointer to
this opaque object?

Do I need to declare some type conversion by hand
or is there a way to make SWIG aware of that kind
of pointer to pointer?

Thanks for helping
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