A min= idiom in C++?

Question

We use

x += y

instead of

x = x + y

And similarly for *,/,- and other operators. Well, what about

x min= y

instead of

x = std::min(x, y)

? Is there a commonly-used idiom for this command, not requiring the (impossible) extension of the language with another operator?

Answer 1

It's certainly not idiomatic, but you might be able to use something called named operators (see these Q&As here and here, developed by @Yakk and @KonradRudolph), and write

x <min>= y;

which is made possible by overloading operator< and operator>, combined with a clever wrapped named_operator. The full code is given by the link above, but uses code like

template <typename T1, typename T2, typename F>
inline auto operator >(named_operator_lhs<T1, F> const& lhs, T2 const& rhs)
    -> decltype(lhs.f(std::declval<T1>(), std::declval<T2>()))
{
    return lhs.f(lhs.value, rhs);
}

Using std::min as template argument for the template parameter F, would update the lhs of the expression with the min of the lhs and rhs.

Answer 2

You can't extend the language in this way. The closest you can come is something like:

template <typename T, typename U>
T&
mineq( T& lhs, U rhs )
{
    if ( rhs < lhs ) {
        lhs = rhs;
    }
    return lhs;
}

This would allow writing:

mineq( x, y );

I question whether it's worth the bother, however.

Answer 3

NO. There is no such thing, you'll have to do with std::min(x,y);