TITLE: namespaces and overloading

(Newsgroups: comp.lang.c++.moderated, 25 June 99)


LAVRIJSEN: Wim Lavrijsen <wlav@atlas06.cern.ch>

>>what are the rules for overloading across namespaces?


NARAN: sbnaran@localhost.localdomain (Siemel Naran)

>I don't think there are any rules.  The bottom line is that when you
>make a function call, there must be only one function to call.


CLAMAGE: Steve Clamage <clamage@eng.sun.com>

More specifically, overloading does not occur across scopes.

If functions are declared in different scopes, something
must be done to make them visible in the same scope -- such
as using-directives or using-declarations -- before they
can participate in overloading.

When you call a function, the visible functions of that name
are compared for the best match. Functions that are not
visible don't get considered.

Examples:

namespace A { int f(int); }
namespace B { int f(double); }
int i = f(1); // error, no f is visible
using A::f;
int j = f(2.0); // calls f(int), because f(double) is not visible
using B::f;
int k = f(3.0);  // both are visible, f(double) is best match