On Mon, 28 Dec 2009 03:02:23 +0300, TM <[email protected]> wrote:
Hello,
I was dealing with delegates when I found that the const correctness of
the this pointer was 'lost' when accessing a member function of a class
through a temporary delegate.
Here is an example:
class A{
void f () {}
}
const A a = new A;
a.f() //error, this is normal.
auto g = &a.f;
g(); //no error. Is this normal ?
I may be wrong, but it seems to me that as the const property of the
this pointer is linked to the instance of the class (here 'a'), the
delegate 'g' should contain a const pointer to A (because 'a' is const).
More generally, I seems that there is no management of the const
correctness of the frame pointer of a delegate in D2
What about adding the const keyword for delegates, as we do for methods
? The const property of the delegate's frame pointer would be part of
its type.
Example:
void f()
{
int x;
void g() const {
x ++; //would produce an error since the type of g is [void
delegate() const]
}
}
Any thoughts about this ?
It shouldn't compile: it makes no sense to can't non-const method through
const reference, and the same applies to shared. OTOH, the following
should just work:
class A {
void constMethod() const {}
void sharedMethod() shared {}
}
const A a1 = new A();
void delegate() const dg1 = &a1.constMethod;
shared A a2 = new shared A();
void delegate() shared dg2 = &a2.sharedMethod();
(in examples above, const and shared attributes are applied to both
function pointer and frame pointer)
I already wrote about a necessity of introduction of "shared delegates" in
a separate thread. Until then, Thread creation is broken in D.
