Re: Question about library-level functions

[AdaMagica <christ-usch.grein@t-online.de>]

On Sunday, December 16, 2012 10:43:41 AM UTC+1, Simon Wright wrote:
> ytomino writes:
>
> > function alloc return access lifetime.T is
> > begin
> >    return new lifetime.T'(lifetime.Create);
> >    -- lifetime.Finalize may be called here
> > end alloc;
>
> I think that what's happening is that a (limited) temporary lifetime.T
> object is created (on the heap, or perhaps the secondary stack). Its
> access is taken for the return value, and then (because we're leaving
> the scope) it gets finalized.

Looks like so, but IMHO this is illegal. A limited object must be created in-place. (Of course an implementation can do as it likes and create first a temporary object, then copy it to the final one and finalize the temporary *if* the result is as though it was created in-place. But here, it seems like the same object is finalized twice.)

What may be temporary and copied it the access value and not the accessed object. It's standard to create an object via an access and return the latter - the object must not be finalized, of course.

Creating via anonymous access is evil - how can ou ever deallocate it? This should be verboten by the language.