[docs] [issue30390] Document how to make classes in the C API.

[Decorater]

New submission from Decorater:

On the C API, it tells how to make modules, functions, variables, and other things, but what about classes?

Like for example if you wanted to make a class with all of the methods having to use direct C Code which would then be converted to PyObject *'s for returning the information the C Code would normally return.

Not only that but also being able to create class instance variables using the C API as well.

Like for example here is an example class (As it would be if it was written in python):

class Example:
    def __init__(self):
        self.data = None  # None being a place holder for now.

    def somefunction(self):
        # C Code here.
        self.data = ret  # return value for the C Code.
        return self.data

Yes, there are better ways than writing the return data to the instance variable and returning it. That is just an example, I have classes that uses them for other things that does not return anything making the instance variables be the only way to get the data.

But yeah long story short I think creating classes with the C API should be documented if not already, or at least an example of doing one to be added as an guide for others wondering how to use the C API to make their own (non exception) classes.

----------
assignee: docs at python
components: Documentation, Extension Modules
messages: 293863
nosy: Decorater, docs at python
priority: normal
severity: normal
status: open
title: Document how to make classes in the C API.
versions: Python 3.5, Python 3.6, Python 3.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue30390>
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