Hello!


The basic_findfile_sequence in winstl has no iterator type defined, only a const_iterator. I noticed that when I tried to use it with BOOST_FOREACH, which requires an iterator type.




So Long...

Gabor

Gabor Fischer Wrote:

> Hello!
> 
> 
> The basic_findfile_sequence in winstl has no iterator type defined, only a const_iterator. I noticed that when I tried to use it with BOOST_FOREACH, which requires an iterator type.

That's by design. A collection that represents a file-system cannot be mutating.

The problem is with BOOST_FOREACH. I don't know how it's implemented, but it clearly makes an invalid assumption - namely, that an STL collection must be mutating. What it should be doing is to use IIA (Inferred Interface Adaptation) to deduce the mutability of the collection, and using the appropriate iterator member type.

Cheers

Matt

Hello Matthew!

>> Hello!
>>
>>
>> The basic_findfile_sequence in winstl has no iterator type defined, only a const_iterator. I noticed that when I tried to use it with BOOST_FOREACH, which requires an iterator type.

> That's by design. A collection that represents a file-system cannot be mutating.

Makes sense.

> The problem is with BOOST_FOREACH. I don't know how it's implemented, but it clearly makes an invalid assumption - namely, that an STL collection must be mutating. What it should be doing is to use IIA (Inferred Interface Adaptation) to deduce the mutability of the collection, and using the appropriate iterator member type.

I have researched a bit more about BOOST_FOREACH and found out how to adapt it so that it can be used with findfile_sequence. One has to add following template specialisation:

namespace boost
{
    // specialize range_iterator in namespace boost
    template<typename C, typename T>
    struct range_iterator<winstl::basic_findfile_sequence<C, T> >
    {
        typedef typename winstl::basic_findfile_sequence<C,
T>::const_iterator type;
    };
}

That's all, and BOOST_FOREACH can be used to iterate over files. I have only tested it with VC++ 2005.




So Long...

Gabor