operator overloading and templates

[Ali Çehreli]

On Tue, 04 Oct 2011 16:24:52 +0000, jimmy wrote:

> Hi,
> 
> I have the following code.
> 
> struct Foo(int DIM) {
> 	Foo!(DIM) opBinary(string op) (Foo!(DIM) rhs)
> 		if (op == "+" || op == "-")
> 	{
> 		return Foo!(DIM)();
> 	}
> }
> 
> unittest {
> 	auto u = Foo!(2)();
> 	auto v = Foo!(2)();
> 	assert(u + v == u);
> }
> 
> I got the following during my test.
> 
> Z:\proj\D\gas>rdmd --main -unittest a.d rdmd --main -unittest a.d
> a.d(12): Error: incompatible types for ((u) + (v)): 'Foo!(2)' and
> 'Foo!(2)'
> Failed: dmd -unittest -v -o- "a.d" -I"." >a.d.deps
> 
> I have no idea why the incompatible types error occurred.

This doesn't answer the issue and the error message above is useless at 
best, but here is a workaround:

    Foo opBinary(string op) (Foo rhs)
    if (op == "+" || op == "-")
    {
        writeln("My type: ", Foo.stringof);
        return Foo();
    }

Within the template definition, the name of the template alone means 
"that particular instantiation of the template".

Ali