Re: [boost] Re: from enumerations to I/O streams

From: David Abrahams (abrahams_at_[hidden])
Date: 2000-10-29 23:19:33

----- Original Message -----
From: "Anton Gluck" <gluc_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Sunday, October 29, 2000 10:56 PM
Subject: Re: [boost] Re: from enumerations to I/O streams

> > ifstream as a parameter. If you don't want to intrude on your class'
> > interface, you can do something like this:
> >
> > struct TextRecordIteratorWrapper : TextRecordIterator
> > {
> >    TextRecordIteratorWrapper(std::ifstream* s) :
> >       TextRecordIterator(*s) {}
> > };
> >
> > ...
> > py::ClassWrapper<TextRecordIteratorWrapper>
> > text_record_class(ClusterForPython, "TextRecordIterator");
> > text_record_class.def(py::Constructor<std::ifstream*>());
> > text_record_class.def(&TextRecordIteratorWrapper::function1,
"function1");
> > ...
>
> Most of this works, except for the last line (exposing a
> TextRecordIterator function, properly renamed of course).

Renamed? How? Why?

> This being an
> iterator, I tried exposing its HasMore and Next functions. I got this
> error:

not that this is relevant, but I don't get the connection between it being
an iterator and having HasMore and Next functions...

> d:\py_cpp/caller.h(32) : error C2665: 'from_python' : none of the 134
> overloads can convert parameter 2 from type 'struct py::Type<class
> TextRecordIterator &>'
>         d:\py_cpp/functions.h(54) : see reference to function template
> instantiation 'struct _object *__cdecl py::Caller<int>::call(int
> (__thiscall TextRecordIterator::*)(void),struct _object *,struct _object
> *)' being compiled
>
> I suppose the move from TextRecordIteratorWrapper to the underlying
> TextRecordIterator causes the problem. Another bug?

I could be wrong, but I think it's not a bug. It looks to me like you wrote
something like
    text_record_class.def(&TextRecordIterator::HasMore, "HasMore");
instead of
    text_record_class.def(&TextRecordIteratorWrapper::HasMore, "HasMore");

Am I right?

-Dave

P.S. I have a bug fix for the non-const-reference-constructor-argument
problem. I was planning on doing more work on the documentation before
posting it, but if you'd like I will post an update sooner.