How to access SWIG Python generated Abstract c++ Class Methods?

This could be something simple I'm missing but I can't find any explanation.

Given an abstract class, which is implemented elsewhere and its interface provided by an exported function:

class IFoo {
public:
    virtual ~IFoo(){}
    virtual void bar()=0;
};

extern IFoo* get_interface();

In c++ I would use this as:

IFoo* foo = get_interface();
foo->bar();

If I SWIG this, I can import the module and assign get_interface() to a variable:

import myfoo
foo = myfoo.get_interface()

But I can't access foo.bar():

>>> foo.bar()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'SwigPyObject' object has no attribute 'bar'

What am I missing?

Thanks!

Here is the full thing if the fragments above aren't clear enough:

The *.i file:

%module myfoo
#define SWIG_FILE_WITH_INIT

%include "myfoo.h"
%{
#include "myfoo.h"
%}

The myfoo.h header:

class IFoo {
public:
    virtual ~IFoo(){}
    virtual void bar()=0;
    virtual void release()=0;
};

extern IFoo* get_interface();

The implementation file (myfoo.cpp)

#include "myfoo.h"
#include <iostream>

class Foo : public IFoo {
public:
    Foo(){}
    ~Foo(){}
    void bar();
    void release();
};

void Foo::bar() {
    cout << "Foo::bar()..." << endl;
}

void Foo::release() {
    delete this:
}

IFoo* get_interface() {
    return new Foo();
}