Writing SOME class methods in C

[Terry Reedy]

On 11/18/2015 2:50 AM, Daniel Haude wrote:
> Hello,
>
> I'm trying to implement some (but not all) methods of a Python class in C.
> What I've found on the Net is:
>   - how to implement entire modules in C so that I can import that module and
>     use the C functions (successfully done it, too).
>   - how to implement entire classes in C
>
> But I can't find any examples of modules which consist of a mixture of C and
> Python,

There at least to be such in the stdlib.  The .py module defined 
*everything* and then ended with

try:
     from _module import *
except ImportError:
     pass

to replace whatever top-level objects were also written in C.  The 
try-except part is optional but let the module run when _module was not 
present.  I believe the string module was once like this.

> nor modules that define classes of which some members are
> implemented in C, others in Python.

I would try putting the C part in separate base or mix-in class, 
imported before the class statement.  To make the C part optional:

class mixin: ...

try:
     from _module import mixin
except ImportError
     pass

class myclass(mixin): ...

-- 
Terry Jan Reedy