On Thu, 31 Mar 2011 14:02:43 -0400, Kagamin <s...@here.lot> wrote:
Steven Schveighoffer Wrote:
The issue is that you can't have two templates with the same exact
template parameters, even if they have different function parameters.
This is because the compiler first instantiates the template, then calls
the function.
If two template instances have the same exact template parameters, it's
one instance, isn't it? There's no need to instantiate it twice.
Yes, but we allow function overloading. Problem is, you can't do
*template* function overloading unless you do it on the template
parameters.
For instance, these two cannot be instantiated:
void foo(string s)(int x) {writeln(x);}
void foo(string s)(string y) {writeln(y);}
because the compiler considers that you defined the same template twice
with different implementations.
However, if you do:
void foo(string s, T)(T x) if (is(T == int)) { writeln(x); }
void foo(string s, T)(T x) if (is(T == string)) { writeln(x); }
then you have two different templates, and the compiler has no issue.
This is a huge nuisance for operator overloading and opDispatch because
the only required template parameter is the string of the
operator/function name.
I suspect that fixing this will be a large change in the compiler.
-Steve
