PyCObject subtype PyObject

[Benjamin Tai]

Hi,


Any comments to clarify my confusion would be appreciated.

In Python/C API Reference Manual, section 7.5.9 CObjects,  the document
mentions that:

"PyCObject This subtype of PyObject represents an opaque value, ..."



1) What does it mean by "subtype"? As a C interface, is the document
talking about two structs which share some common fields?


2) For function "PyCObject_FromVoidPtr()", it takes in a "void*" as the
first argument.
For function "PyCObject_AsVoidPtr()", it returns a "void*".
When implementing Python extension, what is the potential danger of
casting pointers, of different size, to and from "void*"?


3) What if I can always determine the original type of the pointer?


4) Apart from exporting function between modules, are there any examples
of using PyCObject?



Thanks

Ben