On Mon, Nov 30, 2009 at 7:25 AM, Vicente Botet Escriba <vicente.botet@wanadoo.fr> wrote:
"In a nutshell, `common_type` is a trait that takes 1 or more types, and returns a type which all of the types will convert to. The default definition demands this conversion be implicit. However the trait can be specialized for user-defined types which want to limit their inter-type conversions to explicit, and yet still want to interoperate with the `common_type` facility.
Example:
template <class T, class U> typename common_type<complex<T>, complex<U> >::type operator+(complex<T>, complex<U>);
In the above example, "mixed-mode" complex arithmetic is allowed. The return type is described by `common_type`. For example the resulting type of adding a `complex<int>` and `complex<double>` might be a `complex<double>`."
I've needed this feature many times. Can you explain the pros/cons of common_type against Boost.Typeof? Thanks, --Michael Fawcett