Re: msvc++ 2005 template question

From:
"Tom Widmer [VC++ MVP]" <tom_usenet@hotmail.com>
Newsgroups:
microsoft.public.vc.language
Date:
Wed, 18 Oct 2006 17:32:44 +0100
Message-ID:
<OR5uJMt8GHA.2120@TK2MSFTNGP03.phx.gbl>
olli wrote:

I have a library which I want to build on msvc++ 2005. however the
compiler generates the following warnings and errors concerning the
following source snippet:

template <class EOT>
class eoSelectivePopulator : public eoPopulator<EOT>
{
public :

    using eoPopulator< EOT >::src;

    eoSelectivePopulator(const eoPop<EOT>& _pop, eoPop<EOT>& _dest,
eoSelectOne<EOT>& _sel)
        : eoPopulator<EOT>(_pop, _dest), sel(_sel)
        { sel.setup(_pop); };

    /** the select method actually selects one guy from the src pop */
    const EOT& select() {
        return sel(src);
    }

private:

    eoSelectOne<EOT>& sel;
};

---

output is:

eopopulator.h(192) : warning C4346: 'EOT::Fitness' : dependent name is
not a type
prefix with 'typename' to indicate a type
        eopopulator.h(205) : see reference to class template
instantiation 'eoSelectivePopulator<EOT>' being compiled
eopopulator.h(192) : error C2923: 'eoSelectOne' : 'EOT::Fitness' is not
a valid template type argument for parameter 'WorthT'
eopopulator.h(192) : warning C4346: 'EOT::Fitness' : dependent name is
not a type
        prefix with 'typename' to indicate a type
eopopulator.h(192) : error C2923: 'eoSelectOne' : 'EOT::Fitness' is not
a valid template type argument for parameter 'WorthT'
eopopulator.h(204) : warning C4346: 'EOT::Fitness' : dependent name is
not a type
        prefix with 'typename' to indicate a type
eopopulator.h(204) : error C2923: 'eoSelectOne' : 'EOT::Fitness' is not
a valid template type argument for parameter 'WorthT'

I'm not too familiar with templates and the code looks okay to me.
Can someone help me out? Thanks a lot in advance!


How are you using eoSelectivePopulator<EOT>? The errors suggest to me
that you are trying to use eoSelectivePopulator<T> with a T that does
not have a member typedef or nested class named Fitness.

Tom

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