Re: Operator overloading

[Andrei Alexandrescu]

John Reimer wrote:
Hello Andrei,
The Anh Tran wrote:

Andrei Alexandrescu wrote:

auto op(++)(); // bar++
auto op(++)(int); // ++bar
Hey, wasn't the implementation of the postincrement operator through
an overload a rather untasty hack?

Aside for a minor change in notation, there's no improvement. We're
looking for much more broad improvements, such as offering the
ability to overload several operators with only one function.

Andrei

How about this:

Unary op: ++f, ~f, ~f, +f, -f, *f
auto operator(++, --, ~, !, +, -, *)()
{
// posfix is provided by compiler
// and is only used for: foo++ foo--
static if (posfix)
return op(this.value);
else ...
}
Binary op: equality comparison f1 <= f2
bool operator(<, >, <=, >=, ==, !=)(Foo foo)
{
return op(this.value, foo.value);
}
For un-order object, he/she just list 'correct' operator(s) in op()
list. Ex: bool operator(!=, ==)(Foo foo) {}

Why invent new syntax when compile-time strings are already there?

auto operator(string op)() if (op == "++" || op == "--")
{
return mixin(op ~ "this.value");
}
etc. That, of course, is orthogonal to the semantic equivalences
suggested by Don and does not solve fusion.

Andrei



Once again, I'm no expert in this matter, but the compiler-time strings 
idea looks like a great solution for this.  Was this brought up before? 
...because that was kind of what I was thinking when you mentioned a new 
operator overloading syntax for D.

Only in private conversation between Walter and me. But anyway, let's 
not forget we need to address fusion as well.

Andrei