Re: [Implementation] Calling wrapped functions, converters, policies

Daniel Wallin <[email protected]> writes:

>>>Yeah, that would work fine. But I'm not sure I like it. How does it
>>>apply to explicit conversions? (object_cast<> / extract<>). I had
>>>thought that we'd handle these cases by just supplying a vector1<T>
>>> signature sequence.. 
>>     vector2<T,object>  // from-XXX
>> or     vector2<object,T>  // to-XXX
>> Simple ;-)
>
> So we would generate a dummy converter? Hackish. :)

I guess.  You don't like it?

>>>But we could tell the policy to generate the converter explicitly
>>>instead of using generate_converter_tuple<>.. I'm not sure what I
>>>think about this.
>>
>> Not sure what you're driving at here.
>
> We could invoke the nested apply<> explicitly instead of applying it
> while iterating over a signature sequence.
>
>    template<class T, class ConverterGenerator>
>    T extract(..., ConverterGenerator)
>    {
>        typename mpl::apply2<
>            ConverterGenerator
>          , T
>          , mpl::int_<0>
>        >::type cv;
>
>        return cv.convert(...);
>    }

I'm a little bit lost.  Not enough context.  Do I need to follow this?
If so, can you make a new post about just this subject?

>>>Yeah I think we did. I guess most of "the others" will likely just
>>>ignore the index though, provided that the index is passed to the
>>>converter later.
>>>
>>>    struct my_cv;
>>>    my_cv cv;
>>>    cv.from(..., mpl::int<2>());
>>>
>>>vs
>>>
>>>    template<int N>
>>>    struct my_cv;
>>>    my_cv<2> cv;
>>>    cv.from(...);
>>
>> Do we want to pass the index into the converter later?  I don't
>> think we do.  Seems to me that you might want some converters to,
>> ultimately, work on several indices.  Maybe I'm wrong.
>
> No I think you are right. It's a bit annoying to bind the index in
> the converter type though. It does mean we could potentially be
> subject to more code bloat since we are using compile time
> indices.. But I don't know if there's a way around that, at least
> not a good one.

I don't seem to care much ;-) You can't plan for everything.  We can
always rearchitect later.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com



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