On Fri, 18 May 2012 14:30:46 -0400, Andrei Alexandrescu
<seewebsiteforem...@erdani.org> wrote:
On 5/18/12 1:22 PM, Mehrdad wrote:
My brain just exploded.
Can someone explain what's going on?
class Test
{
public void foo() { }
}
static assert(is(typeof(&Test.foo) == void function()));
Looks like a bug. The assert should pass only if foo were static.
No, this is not a bug.
The purpose is so you can get the function pointer portion of a delegate
without an instance of the object.
Possible (obscure) usage:
class Test
{
public void foo() { writeln("foo");}
public void bar() { writeln("bar");}
}
void x(Object context, void function() f1, void function() f2)
{
void delegate() dg;
dg.ptr = cast(void *)context;
if(uniform(0, 2))
dg.funcptr = f1;
else
dg.funcptr = f2;
dg();
}
void main()
{
auto t = new Test;
x(t, &Test.foo, &Test.bar);
}
Another interesting usage is to test if a function has been overridden:
if((&t.foo).funcptr == &Test.foo)
writeln("not overridden!");
I personally think the "feature" is too awkward for any real usage.
Someone once suggested funcptr and &Test.foo should return void *, so the
addresses could be compared, but not used (it's too easy to call this
function).
In any case, not a bug.
-Steve
