Re: [boost] Re: auto_array_ptr

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 
unmolested.

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

Thanks,

--Steve