Re: [Quantlib-dev] QuEP 4: Reducing abstraction penalty by means of disposable arrays

[Luigi B. <lui...@gm...>]

On 05/16/2006 07:52:59 PM, DU VIGNAUD Fran=E7ois wrote:
> The following constructor destroys
> the non disposable object t given as argument:
> (ql/Utilities/disposable.hpp)
>=20
>     template <class T>
>     inline Disposable<T>::Disposable(T& t) {
>         this->swap(t);
>     }

Yes, this is by design. The purpose is to allow one to write

Disposable<Foo> bar() {
     Foo f(1,2);
     return f;
}

and avoid the copy in the automatic conversion from Foo to =20
Disposable<Foo> implied by the return. The problem was that it is =20
difficult to initialize a Disposable directly, as in:

Disposable<Foo> baz() {
     Disposable<Foo> f(1,2);
     return f;
}

because Disposable has no idea of how many arguments the constructor =20
should take, nor of their types. Other approaches might be possible, =20
but I think they make the resulting client code more clumsy.

Luigi


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The first rule of intelligent tinkering is to save all the parts.
-- Paul Erlich