Hello,

I'm not sure if this has already been suggested or not. However, it
seems to me that extending std::less in the following manner would be
useful:

 > template<class T, class F = identity<T> >
 >  class less {
 >  private:
 >    F _s;
 >  public:
 >    bool operator()(T const &a, T const &b) const {
 >      return _s(a) < _s(b);
 >    }
 >  };

The reason behind this is that it allows things like:

 > typedef pair<int,int> p_t;
 > typedef set<p_t,less<p_t,select2nd<p_t> > > nset_t;

Clearly, this also applies to other functors such as greater.

Does anyone agree/disagree ?

Cheers,

David Pearce

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