help with print function in extension

Alex Martelli aleax at
Wed Sep 25 05:26:24 EDT 2002

Eric Hagemann wrote:

> I'm handcrafting an extension in C
> If have defined both a str() and a repr() function and when I execute
> either repr(obj), or str(obj) I get what I expect
> however if I execute 'print obj' I get the following error
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> SystemError: error return without exception set
> although 'print str(obj)' works like I think it should
> Am I mistaken in thinking that  'print str(obj)' should be the same as
> 'print obj'

*ALMOST!*  In the PyTypeObject struct, there's a tp_print slot
that is used by preference, if non-null, when you print something
and stdout is a real file.  What do you have in tp_print for
your type?  It's smack in-between tp_dealloc and tp_getattr.


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