Created attachment 271660 [details] [review]
Patch enabling operator-overloading for +, -, *, /

Hi,

Attached is a patch and a testcase for an operator-overloading feature i implemented for vala. With this patch you can add attributes like '[Semantics(overloads = "+")]' to a method which enables certain binary operations for instances of the class containing the method.

Using a class like
"""
class Foo {
   [Semantics(overloads="+")]
   public Foo add(Foo foo1) {
      ...
   }
}
"""
a statement like
"var foo3 = foo1 + foo2;"
is equivalent to
"var foo3 = foo1.add(foo2);"

When you are interested in this feature i will implement this for other binary operators too.