Re: [Swig-user] Derived use of std::vector

[William S F. <ws...@fu...>]

Sorry for the hastily written email, I did indeed mean -E.

William
Gerwin de Haan wrote:
> William, thanks for your response. We mainly focus on Python, so this
> is my target for now. I'm a bit puzzled by your remark on running SWIG
> -i on std_vector.i , as I cannot find anything on the "-i" parameter.
> I did look at what the -E (preprocessing only) returns. I will try
> some of the copy/paste actions you suggest and see how far this brings
> me.
> Gerwin
> 
> 
> On Sat, Nov 1, 2008 at 10:43 PM, William S Fulton
> <ws...@fu...> wrote:
>> Gerwin de Haan wrote:
>>> Dear list,
>>>
>>> For a while I have been working on SWIG wrappings for the
>>> OpenSceneGraph graphics library. In a newer revision of this library,
>>> some functionality involving std::vector was changed (a MixinVector
>>> class was introduced which mimics the interface of std::vector).
>>> Question in short: Does anyone have experience in wrapping classes
>>> that "derive" from std::vector (or classes with similiar style)?  Can
>>> I apply "macros" that are used to wrap std_vector.i on other/derived
>>> classes directly?
>>> If this triggers anything, please read on for an extended description
>>> of my problem.
>>>
>>>
>>>
>>> Before, I was happily using the std_vector.i constructions to allow
>>> direct access to std::vector types, e.g. I could use arrays of the
>>> Vec2 type:
>>>
>>> --- osg C++ ---
>>> template<typename T, Array::Type ARRAYTYPE, int DataSize, int DataType>
>>> class TemplateArray : public Array, public std::vector<T>
>>> {...}
>>> --- SWIG ---
>>> %template(vectorVec2)     std::vector<osg::Vec2>;
>>> %template(Vec2Array)
>>> osg::TemplateArray<osg::Vec2,osg::Array::Vec2ArrayType,2,GL_FLOAT>;
>>> --- Python ---
>>> v2a = osg.Vec2Array()
>>> v2a.push_back(osg.Vec2(1,2))
>>>
>>> In the newer revision of OpenSceneGraph, a MixinVector class was
>>> introduced which mimics the interface of std::vector by passing almost
>>> all functionality to a std::vector member.
>>>
>>> --- osg C++ ---
>>> template<typename T, Array::Type ARRAYTYPE, int DataSize, int DataType>
>>> class TemplateArray : public Array, public MixinVector<T>
>>> {...}
>>> template<class ValueT>
>>> class MixinVector
>>> {
>>>    typedef typename std::vector<ValueT> vector_type;
>>> public:
>>>    typedef typename vector_type::allocator_type allocator_type;
>>>    typedef typename vector_type::value_type value_type;
>>>    const_reference operator[](size_type index) const { return
>>> _impl[index]; }
>>>    reference operator[](size_type index) { return _impl[index]; }
>>>    const_reference at(size_type index) const { return _impl.at(index); }
>>> ...}
>>> --- SWIG ----
>>> %template(mixinVectorVec2)      osg::MixinVector<osg::Vec2>;,
>>>
>>> After SWIGging, the compiler complains a lot, mainly at
>>> const_reference functions and operators:
>>> python/osgPYTHON_wrap.cxx: In function \u2018PyObject*
>>> _wrap_mixinVectorVec2_at__SWIG_0(PyObject*, PyObject*)
>>> python/osgPYTHON_wrap.cxx:166534: error: \u2018result\u2019 declared
>>> as reference but not initialized
>>> python/osgPYTHON_wrap.cxx:166563: error: passing \u2018const
>>> osg::Vec2f\u2019 as \u2018this\u2019 argument of \u2018osg::Vec2f&
>>> osg::Vec2f::operator=(const osg::Vec2f&)\u2019 discards qualifiers
>>> python/osgPYTHON_wrap.cxx:166574: error: cannot declare reference to
>>> const class osg::Vec2f&
>>> python/osgPYTHON_wrap.cxx:166574: error: new cannot be applied to a
>>> reference type
>>> python/osgPYTHON_wrap.cxx:166574: error: invalid conversion from const
>>> void* to void*
>>> python/osgPYTHON_wrap.cxx:166574: error:   initializing argument 1 of
>>> PyObject* SWIG_Python_NewPointerObj(void*, swig_type_info*, int)
>>> ...
>>>
>>> As this new MixinVector class is so similar to std::vector, I was
>>> hoping this could be solved "elegantly":
>>> I was wondering if anyone has experience in wrapping classes that
>>> "derive" from std::vector (or classes with similiar style)?
>>> Should I manually remove/fix the const problems or can I reuse some of
>>> the std_vector.i present in SWIG?
>>> Or, can I apply "macros" that are used to wrap std_vector.i on
>>> other/derived classes directly?
>>>
>>> any thoughts are welcome,
>>> Gerwin
>>> code.google.com/p/osgswig
>> From your link above you are supporting Python, Ruby, Java and Lua. The
>> std::vector library files are quite different for each and support different
>> aspects of std::vector. Replicating all could be quite hard unless you just
>> do a copy paste kind of approach of the SWIG std::vector library for each of
>> these target languages. The easiest is probably to run SWIG -i on
>> std_vector.i and copy paste and change std to osg and vector to MixinVector.
>> You'll see that there is a lot of code developed for some of these target
>> languages and you could provide a much simpler cut down api, something
>> similar to the Java approach, see Lib/java/std_vector.i.
>>
>> William
>>
>