Re: Generic operator implementation, pointer to POD type's operators
Carl Barron ha scritto:
In article <MIm6i.20864$U01.245529@twister1.libero.it>, Alberto Ganesh
Barbati <AlbertoBarbati@libero.it> wrote:
Why are you using pointer to function in the first place where you could
use functors instead? You don't even have to invent functions because
the STL already define most of them for you:
std::plus<T> etc can produce unwanted copies of the left operand,
that is why. Your compiler might optimize
int t,x;
x = std::plus<int>()(x,t);
to x += t but don't count on it:)
Well, if the compiler doesn't do that for basic types then it's a very
poor compiler. OTOH, the compiler won't surely apply such optimization
for UDTs, because for UDTs operator+ and operator+= are, from the
compiler point of view, unrelated functions.
If that is a concern, just define your own functors that do whatever you
want them to do. For example:
template <class T>
struct add_assign
{
void operator()(T& x, const T& y) const { x += y; }
};
The point of my suggestion was about using functors instead of function
pointers, the use of STL functors was merely accidental.
Ganesh
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