[Python-Dev] Why is type_modified() in typeobject.c not a public function? (original) (raw)

Stefan Behnel stefan_ml at behnel.de
Wed May 28 07:47:16 CEST 2008

Hi,

Guido van Rossum wrote:

On Tue, May 27, 2008 at 9:47 AM, Stefan Behnel <stefanml at behnel.de> wrote:

Could this function get a public interface? I do not think Cython is the only case where C code wants to modify a type after its creation, and copying the code over seems like a hack to me.

I'm fine with giving it a public interface. Please submit a patch with docs included.

Straight forward patch is attached (against 3.0a5). Works for me in Cython. I thought about a name like "Taint(t)" or "ClearTypeCache(t)", but then went with the coward solution of calling the function PyType_Modified() as it was (almost) named internally.

BTW, I noticed that the code in typeobject.c uses "DECREF before set" two times, like this:

    method_cache[h].version = type->tp_version_tag;
    method_cache[h].value = res;  /* borrowed */
    Py_INCREF(name);
    Py_DECREF(method_cache[h].name);
    method_cache[h].name = name;

During the call to Py_DECREF, the cache content is incorrect, so can't this run into the same problem that Py_CLEAR() aims to solve? I attached a patch for that, too, just in case.

Stefan

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