Boost Python v2 - extending and embedding - memory leaks, compiler warnings

From: texrmex (texrmex_at_[hidden])
Date: 2002-11-04 18:27:52

First, I'm excited about the new work that's been done with Boost 
Python v2.  I can't wait to see if it's enough to overcome the 
pitfalls that prevented me from getting past the evaluation stage 
with v1.

I'm using VC7 IDE to build my project and link to python22.lib and 
boost_python.lib (built with VC7 command line tools using bjam).  I'm 
attempting to extend and embed in my existing project, so I'm not 
building a dll, but and exe.  First of all, can I do this?  When it 
links it says "Creating library ....lib and object ....exp", and 
still creates an exe.  If I don't include my test module (and thus 
boost/python.hpp) I don't get this message.  I'm assuming that by 
defining a module, boost defines exports and the linker then creates 
the lib and exp, since there were exports?  Although I've built dlls 
before, I really don't know the inner workings of the process.

The following is a brief example of my module.  At the bottom is a 
simple test function that I'm calling just to test importing of the 
module.  When I call TestModule(), I get 2 memory leaks from the 
module definition section, one from the class definition, and the 
other from the method definition.  If I remove these, I get no memory 
leaks, and if I add more classes and methods, I get one 12 byte leak 
per class and one 12 byte leak per method I add.  I do not get a leak 
from defining the top level function "greet".

///////////////////////////////////////////////////
#include <boost\python.hpp>
using namespace boost::python;

namespace {

const char * greet() {
    return "Hello World";
}

class CSimple
{
public:
        bool Test() { return true; }
};

};

BOOST_PYTHON_MODULE(Test)
{
    def("greet", greet);

    class_<CSimple>("Simple")
        .def("Test", &CSimple::Test)
    ;
}

void TestModule()
{
    Py_Initialize();
    initTest();
    Py_Finalize();
}
///////////////////////////////////////////////////

In addition to the memory leaks, I get a number of compiler warnings, 
similar to the following:

d:\Boost\boost\python\instance_holder.hpp(18) : warning C4275: non 
dll-interface class 'boost::noncopyable' used as base for dll-
interface struct 'boost::python::instance_holder'
        d:\Boost\boost\utility.hpp(50) : see declaration 
of 'boost::noncopyable'
        d:\Boost\boost\python\instance_holder.hpp(17) : see 
declaration of 'boost::python::instance_holder'

*and*

d:\Boost\boost\python\detail\exception_handler.hpp(34) : warning 
C4251: 'boost::python::detail::exception_handler::m_impl' : 
class 'boost::function2<R,T0,T1,Policy,Mixin,Allocator>' needs to 
have dll-interface to be used by clients of 
struct 'boost::python::detail::exception_handler'
        with
        [
            R=bool,
            T0=const boost::python::detail::exception_handler &,
            T1=const 
boost::function0<void,boost::empty_function_policy,boost::empty_functi
on_mixin,int> &,
            Policy=boost::empty_function_policy,
            Mixin=boost::empty_function_mixin,
            Allocator=int
        ]

I was wondering if my project is not set up properly, and if these 
warnings might have something to do with the memory leaks.

In v1 there was a vc project you could use for building boost 
python.  This works well if you are planning on linking to a vc built 
project, since you can make sure your settings, paths and libs are 
consistent between the boost python lib and your project.  I 
currently have 3 different sets of build tools (yes, 3 compilers) on 
this box, with several different versions of standard and other 
libraries, so making sure I have control of the paths and settings 
used is very important.  

This is one reason I'm weary of the jam environment.  It's yet 
another build environment, one that I'm not familiar with, and one 
that I'm not going to be using with any other projects except to 
build boost python.  So a question would be: how easy would it be for 
me to set up a VC project for building boost python?  Has this 
already been done?  Or am I barking up the wrong tree?

Thanks in advance,
-Tex