[C++-sig] confused...

[Nicodemus]

Paul Rudin wrote:

>Should this work? If not is there an obvious way to make it work? TIA.
>
>
>Say subclassTest.cpp contains:
>
>---------------------
>#include <boost/python.hpp>
>using namespace boost::python;
>
>class Base
>{
>public:
>  virtual int foo(int x) { return x+1;}
>};
>
>class Bar 
>{
>public:
>  Base* thing;
>  void setThing(Base* bptr) { thing=bptr;};
>  int callThing(int x) {return thing->foo(x);};
>};
>
>class BaseWrap : public Base
>{
>public:
>  BaseWrap(PyObject* self_):self(self_){}
>
>  int foo(int x)
>  {
>    return call_method<bool>(self,"foo",x);
>  }
>

Here you mean:
    return call_method<int>(self, "foo", x);
                       ^^^

Right?

>  PyObject* self;
>};
>
>
>BOOST_PYTHON_MODULE(subclassTest)
>{
>
>
>  class_<Base, BaseWrap, boost::noncopyable >("Base")
>    .def("foo", &BaseWrap::foo)
>    ;
>
>  class_<Bar>("Bar")
>    .def("setThing", &Bar::setThing)
>    .def("callThing", &Bar::callThing)
>    ;
>
>};
>
>---------------------
>
>Then in python:
>
>  
>
>>>>from subclassTest import *
>>>>class sub(Base):
>>>>        
>>>>
>... 	 def foo(z):
>... 	     z=z+7		
>... 
>
Change sub to:

 >>> class sub(Base):
...     def foo(self, z):
...         return z+7
...

Note the "self" argument in the method. In Python, the "self" ("this" in 
C++) is explicity.

>>>>s=sub()
>>>>bar=Bar()
>>>>bar.setThing(s)
>>>>bar.callThing(2)
>>>>        
>>>>
>Traceback (most recent call last):
>  File "<stdin>", line 1, in ?
>TypeError: foo() takes exactly 1 argument (2 given)
>  
>

Hope that helps,
Nicodemus.