[C++-sig] Re: yet another: TypeError: No to_python (by-value) converter found for C++ type:

[tALSit de CoD]

Thanks David....

I understand it more now, but, from what I've been trying to implement, it
still doesnt work.

Here's a simplification of the problem:

class A {
public:
  const std::string & getName ();
private:
  std::string m_name;
};

class B {
public:
  const std::vector <A *> & getAs () { return m_listOfA; }
private:
  std::vector <A *> m_listOfA;
};

Now, i try to export the classes:

boost::indirect_iterator <std::vector <A *>::iterator>
	ABegin (std::vector <A *> & v) {
		return boost::make_indirect_iterator (v.begin ());
};

boost::indirect_iterator <std::vector <A *>::iterator>
	AEnd (std::vector <A *> & v) {
		return boost::make_indirect_iterator (v.end ());
};


BOOST_PYTHON_MODULE (kikura) {
	class_ <A> ("A")
		.def ("getName", &A::getName, return_internal_reference <> ())
	;

	class_ <B> ("B")
		.def ("getAs", &B::getAs, return_internal_reference <> ())
	;

	//----------------------------------------------------------------
	class_ <std::vector <A *> > ("AList")
		.def("__iter__", range (ABegin, AEnd))
	;

}

Now, that will fail, and say that:

TypeError: No to_python (by-value) converter found for C++ type: class A

If I didn't use the range method, it would give me this:

TypeError: No to_python (by-value) converter found for C++ type: class A*

Any clues?

Thanks for all help...


> "tALSit de CoD" <talsit at talsit.org> writes:
>
>> Hmm... i've been trying to understand it, i've read the docs... but...
>> ummm... i can't quite understand it very well...
>>
>> Does this mean that when my class does:
>>
>> const std::vector <cNodeDescriptor *> cRegistry::getDescriptors ();
>>
>> i have to replace that with this:
>>
>> boost::indirect_iterator<std::vector<cNodeDescriptor*>::iterator>
>> cRegistry::getDescriptors ();
>
> I have no idea what getDescriptors is, so it's hard to comment.
>
>> Or am i just totally missing the point?
>>
>> Most of the template magic voodoo still baffels me... :D
>
> There's no template magic voodoo to understand this.
>
>   Try using range
>   (http://www.boost.org/libs/python/doc/v2/iterator.html#range-spec)
>
> Do you understand what range does?
>
>    with functions that return
>    boost::indirect_iterator<std::vector<cNodeDescriptor*>::iterator>
>    wrapped around the vector's begin() and end().
>    (http://www.boost.org/libs/iterator/doc/indirect_iterator.html)
>
> By this I mean
>
>   boost::indirect_iterator<std::vector<cNodeDescriptor*>::iterator>
>   my_begin(std::vector<cNodeDescriptor*>& v)
>   {
>        return boost::make_indirect_iterator(v.begin());
>   };
>
>   boost::indirect_iterator<std::vector<cNodeDescriptor*>::iterator>
>   my_end(std::vector<cNodeDescriptor*>& v)
>   {
>        return boost::make_indirect_iterator(v.end());
>   };
>
> so, something like:
>
>   class_ <std::vector <cNodeDescriptor *> > ("cNodeDescriptorList")
> 	  .def("__iter__", range(my_begin, my_end))
>       ;
>
>
> HTH,
>
> --
> Dave Abrahams
> Boost Consulting
> http://www.boost-consulting.com
>
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>


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