Re: [pygccxml-development] copy constructor woes

[Roman Y. <rom...@gm...>]

On 5/29/06, Lakin Wecker <lak...@gm...> wrote:
> In working some more on the bindings for Ogre, I tried to compile the
> following class:
> http://lakin.weckers.net/ogre/cpp/Frustum.pypp.cpp
>
> The Frustum class that Ogre defines has a member variable:
>
> VertexData mVertexData;
>
> But VertexData defines a protected Copy constructor.  Now, Ogre
> compiles and works fine, because the Frustum class itself doesn't
> define a copy constructor, and no code uses the copy constructor, (So
> it's not generated by the compiler, iirc).
>
> However, in the generated wrapper, the Copy  Constructor is used, and
> then g++ generates the appropriate error:
>
> g++ `pkg-config --cflags OGRE` -I/usr/include/python2.4
> -DBOOST_PYTHON_MAX_ARITY=3D16 -fPIC -Icpp -c -o cpp/Frustum.pypp.os
> cpp/Frustum.pypp.cpp
> /home/lakin/.local/include/OGRE/OgreFrustum.h: In copy constructor
> 'Ogre::Frustum::Frustum(const Ogre::Frustum&)':
> /home/lakin/.local/include/OGRE/OgreVertexIndexData.h:43: error:
> 'Ogre::VertexData::VertexData(const Ogre::VertexData&)' is private
> /home/lakin/.local/include/OGRE/OgreFrustum.h:62: error: within this cont=
ext
> cpp/Frustum.pypp.cpp: In constructor
> 'Frustum_wrapper::Frustum_wrapper(const Ogre::Frustum&)':
> cpp/Frustum.pypp.cpp:13: warning: synthesized method
> 'Ogre::Frustum::Frustum(const Ogre::Frustum&)' first required here
> scons: *** [cpp/Frustum.pypp.os] Error 1
> scons: building terminated because of errors.
>
> I'm going to file a bug with the Ogre guys, as I'm fairly certain that
> they would want to define a copy constructor that works. :)

I am almost sure, they will put it to be private, without any implementatio=
n.

> OGRE's api and general usage pattern will avoid copy constructors, using =
and
> passing around pointers.  However, that leads to a question:  Is this
> also a bug in pyplusplus?

Any time, the generated code could not be compiled it is a bug in py++ :-).

Fixed, committed.
The bug was in is_noncopyable function in type_traits.py module.
I did not take into account member variables of the class. Now this
function will return
True is:
    one of the base classes is noncopyable
    contains const member variable to fundamental type, class or enum
    contains member variable of noncopyable class

I understand, that this is not a complete list of all cases, I will
add treatment to new
use cases, when we will have them.

Also, I updated unit test it is possible I missed some use case. Quick
work around
is

mb =3D module_builder_t( ... )
Frustum =3D mb.class_( 'Frustum' )
Frustum.noncopyable =3D True

But you still need the latest Subversion :-(.


--=20
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/