Dynamic Closure + Lazy Arguments = Performance Killer?

[Frits van Bommel]

> On Sat, Oct 25, 2008 at 10:44 AM, Denis Koroskin <2korden at gmail.com> wrote:
>> I also think that scope and heap-allocated delegates should have different
>> types so that no imlicit casting from scope delegate to heap one would be
>> possible. In this case callee function that recieves the delegate might
>> demand the delegate to be heap-allocated (because it stores it, for
>> example).

How would this work? For example:
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struct Struct {
     // fields...

     void foo() {
         // body
     }
}

void bar(Struct* p) {
     auto dg = &p.foo;	// stack-based or heap-based delegate?
     // do stuff with dg
}
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?
(There's no way to know if *p is a heap-based or stack-based struct)

Jarrett Billingsley wrote:
> Fantastic.  That also neatly solves the "returning a delegate"
> problem; it simply becomes illegal to return a scope delegate.

Even if "scope delegate" becomes a different type, sometimes such a 
"scope delegate"s is perfectly safe to return:
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alias scope void delegate() dg;
Dg foo(Dg dg) {
     return dg;	// Why would this be illegal?
}
-----