My apologies Victor. It seems that the browser on my netbook shown only the part of changes and I seen only the change in array_array___reduce_ex__().

I like Nick's idea for hiding the indirection, but passing var_decl doesn't look having much sense to me. It should always be "static PyObject *".

I don't have a preference for the name, but the purpose of a new API is not just to ensure that a piece of initialization code is executed at most once, but that the object will be destroyed and the reference will be cleared after finalizing the interpreter. Seems this is different from the purpose of pthread_once().