Boost logo

Boost :

From: Stephen C. Gilardi (squeegee_at_[hidden])
Date: 2001-04-06 10:44:37

> > The caveat about temporary smart pointer objects still applies. My rule is
> > "never create an unnamed temporary smart pointer." The non-const reference
> > idiom tries to enforce this rule... although I have another reason for
> > preferring pass by non-const reference:
> >
>> void f(T arg);
> >
> > T t;
>> f(t);
> >
> > // now t is unchanged, right?
>Wrong, of course. Usually, the declaration of f isn't visible near the call,
>so you can't assume much about what's changed. But this case could be seen
>as an argument for using the unnamed temporary... then there's no object
>hanging around with a confusing value.

I don't see how t's value could be changed in the above example.
Could you please explain?

It seems to me that t was passed by value. My understanding is that
an unnamed temporary of type T is constructed using T's copy
constructor and sent to the body of f. This leaves t completely

If my understanding is incorrect, I'll be very happy to learn what
really happens.



Boost list run by bdawes at, gregod at, cpdaniel at, john at