Re: Why is the destructor called multiple times after I declare an object?

[Bob Duff <bobduff@theworld.com>]

Brian Drummond <brian@shapes.demon.co.uk> writes:

> Somehow I expected "extended return" to allocate space and "build in 
> place" during the execution of the return statement. 

Build-in-place is done for return of immutably-limited types,
whether or not the extended return syntax is used.

For nonlimited types, the compiler is free to use build-in-place if it
can prove that it's equivalent to return-by-copy.  It's often not
equivalent.  For example:

    X := Init;

What if Init raises an exception after partly modifying the result?
In that case X should not be modified, so the result object of Init
and X had better not be at the same address.

- Bob