[C++-sig] Re: Creating an instance of a python class derived from a C++ object from C++

[David Abrahams]

"Brian Hall" <bhall at gamers-fix.com> writes:

>>
>> Now say I want to dynamically create an instance of a python class derived
>
>> from MyCppClass like so:
>>
>> class MyPythonClass(MyCppClass):
>>   def SomeFunction(self):
>>     return 42
>>
>> But I want to do this from C++, not Python... how would I do this?  
>
> Use the metaclass interface:
>
>     // returns a new class
>     object make_bar
>     {
>         object bases = make_tuple(py_cState);
>         dict attributes;
>         attributes['x'] = 1;
>         attributes['quack'] = quack;
>
>         return py_cState.attr("__class__")("bar", bases, attributes);
>     };
>
> ----------------
>
> While this is very very cool, I think you misunderstand me... I have the
> python script, and I want to instantiate a python object of type
> MyPythonClass from C++ not define it from C++.

Wrap this:

     object make_one(object some_class)
     {
        return some_class();
     }

in python:

   >>> make_one(MyPythonClass)
   >>> <my_module.MyPythonClass object at 0xwhatever>


-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com