Re: template argument deduction for overloaded predicates

From:
SG <s.gesemann@googlemail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Wed, 7 Nov 2012 09:40:06 -0800 (PST)
Message-ID:
<ee4fcaa8-9f10-4477-b75e-cc714c6ed96e@c20g2000vbz.googlegroups.com>
On Nov 6, 6:10 pm, MJanes <max....@googlemail.com> wrote:

{ Your article lacks the context of what it's referring to.
  Please include some quoting to establish the context. -mod }

I forgot one thing: of course, regarding your original std::all_of
use case, a simpler solution could be just something like:


  struct A {};
  struct B {};

  bool p(A const&);
  bool p(B const&);

  template<class Iter, class Pred>
  void callP(Iter iter, Pred pred);

void f()
{
   std::vector<A> as;
   callP( as.begin(), static_cast<bool(*)(A const&)>( p ) );
}


Or better yet:

     callP( as.begin(), [](A const& x){return p(x);} );

The difference is that in this case the callP specialization directly
calls your lambda (which can be inlined) and your lambda directly
calls p (which could also be inlined if the definition of p is
available in the same translation unit or you can use LTO) -- as
opposed to an indirect function call via function pointer.

Cheers!

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