On 02/12/2012 09:56 PM, Mike Wey wrote:
On 02/12/2012 09:08 PM, Walter Bright wrote:
It's a Base, not an Object. It can be converted to an Object.
Doesn't that break Polymorphism?
You should be able to use Base as if it is an Object without a cast.
_______________________________________________
dmd-beta mailing list
[email protected]
http://lists.puremagic.com/mailman/listinfo/dmd-beta
According to the documentation a == b is rewritten to
.object.opEquals(a, b); if a and b are both objects.
And while .object.opEquals(new Base(), new Base()); compiles without an
error, and gives the expected result at runtime. using == is an
compiletime error when a opCast is supplied without adding one for Object.
Base being derived from Object there would be no need for a cast when
you want to use it as an Object.
Adding an opCast overload for Object solves the compiletime error but,
the added opCast doesn't do anything:
Base opCast(T)()
if ( is(T == Object) )
{
return this;
}
Yes i used Base as the return type, that works because base is derived
from Object.
Is the behavior of the beta really correct?
module test;
class Base
{
override bool opEquals(Object obj)
{
return true;
}
//Base opCast(T)()
// if ( is(T == Object) )
//{
// return this;
//}
T opCast(T : Base)()
{
return this;
}
}
void main()
{
// Works.
assert(.object.opEquals(new Base(), new Base()));
//Error: template instance opCast!(Object) opCast!(Object)
// does not match template declaration opCast(T : Base).
assert(new Base() == new Base());
}
_______________________________________________
dmd-beta mailing list
[email protected]
http://lists.puremagic.com/mailman/listinfo/dmd-beta
