--- Comment #8 from Kenji Hara <> 2011-09-20 13:50:24 PDT ---
Sorry, that was imcomplete.

(In reply to comment #6)
> Example:
> ubyte[B.sizeof] mem=void;
> emplace!B(mem.ptr);//Does this call to B's constructor call A's dtor on some
> kind of trash then?

void main()
    ubyte[B.sizeof] mem=void;
    writefln("%s %s %s", A.ctor,, A.dtor);//prints 0 0 1
    writefln("%s %s %s", B.ctor,, B.dtor);//prints 0 0 1
    // emplace calls A's ctor through calling B's ctor.

> And that's a problem. I mean even when emplace is working and all. Do we 
> really
> want everybody to write emplace(&a, dummy); to do initialization in
> constructor?
> Seems very backwards.
> I'd hate it if this will be some kind of rule #22 of how to do things 
> correctly
> in D.

I think the cases that actually needs emplace is rare.
In most cases, it is rare that T.init has a meaningful state.

(In this context, 'meaningful' means calling destructor against T.init does
e.g. reference counter == 0, class reference == null, ...)

Therefore, destructor calling with assignment against T.init like `a =
A(dummy)` does not make problems usually.

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