[Boost-users] [Range] Predicate type checking.

Subject: [Boost-users] [Range] Predicate type checking.
From: Robert Jones (robertgbjones_at_[hidden])
Date: 2012-05-02 08:13:10

I'm pretty sure I'm have a 'Doh!' moment here, but why does this compile?

Surely the last line of main is gibberish; the value type of m is pair, not
S, so int_from_S
is not a valid function?

#include <boost/range.hpp>
#include <boost/range/adaptor/transformed.hpp>
#include <map>

struct S
{
    S( ) { }
    int i;
};

int int_from_S( S s ) { return s.i; }

int main( )
{
    std::map<unsigned, S> m;
    m[0]=S();
    m | boost::adaptors::transformed(int_from_S);
}

Thx,

- Rob.