Python/C API and setattr

Thomas S. Strinnhed thstr at
Thu Jun 10 07:37:56 CEST 1999


Michael P. Reilly wrote:
> [quoted my message] 
> Thomas, the prototype for functions in the setattr slot of a Python type
> is:
>   typedef int (*setattrfunc)(PyObject *, char *, PyObject *);
> Your counter_setattr function should return an int, true (0) for
> success, false (-1) for error.  I believe the source code and Mark's
> book (somewhere in Ch 15? but I don't have the book with me) are about
> the only places this is documented, and it is very obscure.
> "This looks like a job for Documentation Man!"
>   -Arcege

Thanks everyone, I finally managed to get it all to work.
Embarrassing enough, the answer was in the Programming Python-book all
the time (in ch.14 at p.561), but as said below: "it is very obscure".

Actually we were all almost right, the prototype in the book is
 static int mytype_setattr(mytype *x, char *name, PyObject *value);
so the problem was me trying to return nothing at all, None, the
int value assigned and so on.

I guess this answers a question from an earlier thread:
 "Programming Python" still worthwhile?
with a big: "Yes, very much so!" (as goes for :-)

If anyone is interrested I've pasted the code to my function
as it turned out below. 

Many Thanks
 -- Thomas S. Strinnhed. thstr at

static int counter_setattr(counterobject *self, char *name, PyObject *v)
   if(strcmp(name, "value") == 0)
      self->value = (int)PyInt_AsLong(v);
      return 0;	
   return -1;

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