Extending Python with MyClass

Question

I've read the tutorials on how to extend python with my own module with my own functions:

http://docs.python.org/release/3.1.3/extending/embedding.html#embedding-python-in-c

But how do I extend python so that my module contains a class which I can use in python? A class I have programmed in C++.

I've tried using boost::python earlier but bjam hangs on me when I try to build on mac os x. I'd like to keep things simple as my requirement is very simple:

I have three functions in my module which I call initialise(), run() and close().

At the moment I do this in python:

import mymodule
mymodule.initialise()
mymodule.run()
mymodule.run() # run again
mymodule.close()

I'd like to have a class with initialise() as the constructor, run() as my method, and close() as my destructor. I can then do this:

import mymodule
with mymodule.MyClass as my_class:
    my_class.run()
    my_class.run()

Here's some of my code at the moment:

static PyMethodDef MyModuleMethods[] = 
{
    {"initialise",  mymodule_initialise, METH_VARARGS, ""},
    {"run",  mymodule_run, METH_VARARGS, ""},
    {"close",  mymodule_close, METH_VARARGS, ""},
    {NULL, NULL, 0, NULL}        /* Sentinel */
};

Thanks,

Barry

If the class is something you wrote yourself, you could import from it implicitly in the files as necessary. — Makoto
– Makoto, Commented Mar 21, 2012 at 20:58

Community · Accepted Answer · 2017-05-23 11:48:50Z

1

Take a look at https://stackoverflow.com/questions/1492755/python-c-binding-library-comparison for a comparison of the various tools that will assist you in interfacing C++ with Python especially if you are producing bindings for an entire library of C++ code.

Also, see http://wiki.python.org/moin/IntegratingPythonWithOtherLanguages for a similar list of information directly from Python.org

Edit:

That was a pretty substantial change to your question :) The with statement requires implementing __enter__ and __exit__ as your entry and exit points. Did you try using those method names in your C++ class? See http://effbot.org/zone/python-with-statement.htm and http://www.python.org/dev/peps/pep-0343/ for more info on the with statement.

edited May 23, 2017 at 11:48

CommunityBot

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answered Mar 21, 2012 at 21:05

gfortune

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1 Comment

Baz Over a year ago

I haven't got that far yet, I will begin by calling close() explicitly once I can create my object. Then I'll worry about with.

Baz · Accepted Answer · 2012-03-21 22:09:57Z

0

I finally found this: http://docs.python.org/extending/newtypes.html

edited Mar 21, 2012 at 22:09

answered Mar 21, 2012 at 21:41

Baz

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