On Fri, 24 Jul 2009 09:56:41 -0400, grauzone <n...@example.net> wrote:
LOOKUP_TABLE[0] = Method("method1", &Component.method1);
LOOKUP_TABLE[1] = Method("method2", &Component.method2);
These two lines are weird. ``pragma(msg)`` shows that type of
``&method1`` is ``void function()`` while it must be ``void
delegate()``
for a non-static member because of difference in calling convention.
Actually I think that taking an address of a non-static member in a
static context must be a compile time error.
It's because I'm taking the address of the function on the type, not
on an instance. It's not a delegate because there's no "this" pointer
yet.
It makes sense to me anyways. A delegate is a normal function pointer
coupled with a hidden context parameter.
But you can't call that function pointer. Actually, you can probably
subvert type safety, because functions have a different calling
conventions from delegates. This also means that SafeD should disallow
taking the address of methods from a type (without instance).
That's really silly. A nicer way would be to make &Type.method return a
delegate with ptr set to null. Then calling this delegate would result
in a (harmless) null pointer exception.
But even then, there's no safe way to construct a real delegate out of
the method pointer. You can't simply assign an object instance to ptr,
because you can't statically know if the funcptr of the delegate really
is a method of that object instance.
You mean no *compiler verifyable* safe way. Of course there are provably
safe ways to do it (my code is one of them).
Looks like SafeD proves to be unfeasible again.
That's why there are system modules ;) Note that a delegate's ptr method
is a pointer, so you can't assign it/use it from SafeD anyways.
I'd propose a system module that defines an "unbound delegate" type. This
would be a function pointer coupled parameterized with a type, which has
an opCall(T, ...) that would call the function properly. I think it can
be done, but I'm not enough of a template guru to do it myself.
That could be used in SafeD.
-Steve
