[C++-sig] Re: Problem: held type, std::auto_ptr, ReferenceErrors.

[Nicodemus]

David Abrahams wrote:

>Prabhu Ramachandran <prabhu at aero.iitm.ernet.in> writes:
>  
>
>>    DA> struct Foo_Wrapper : Foo {
>>    DA>    Foo_Wrapper(PyObject* self)
>>    DA>      : m_self(self) {}
>>
>>    DA>    Foo* f() {
>>    DA>        object self(handle<>(borrowed(m_self)));
>>    DA>        return extract<Foo*>(self.attr("f")());
>>    DA>    } 
>>    DA>    PyObject* m_self;
>>    DA> };
>>
>>Yes, that is possible but I'm using Pyste.  Maybe we need another hook
>>to insert code there?  
>>    
>>
>
>I guess that's up to Nicodemus.
>  
>

You can do that already, you just have to write a wrapper for f. Here's 
an example:

---------------- foo.h:

struct Foo
{
    virtual int f() { return 0; }
};


--------------- foo.pyste

Include('iostream')
f_wrapper = Wrapper('f_wrapper',
'''
int f_wrapper(Foo *foo) {
    std::cout << "f!" << std::endl;
    return foo->Foo::f();
}
''')

Foo = Class('Foo', 'foo.h')
set_wrapper(Foo.f, f_wrapper) 


Will generate this:

int f_wrapper(Foo *foo) {
    std::cout << "f!" << std::endl;
    return foo->Foo::f();
}

namespace  {

struct Foo_Wrapper: Foo
{
    ...

    int f() {
        return call_method< int >(self, "f");
    }

    int default_f() {
        return f_wrapper(this);
    }

    ...
};    

                       


But perhaps this is not enough, since the method in the original post 
needed to access the PyObject* of the Wrapper class. Is it possible to 
get the PyObject* given a Foo instance?

Regards,
Nicodemus.