Re: Intervention needed?

["Randy Brukardt" <randy@rrsoftware.com>]

"Jere" <jhb.chat@gmail.com> wrote in message 
news:f610da94-1309-4cb6-8c7b-47f3099381e5@googlegroups.com...
...
> I don't know if you saw my earlier question to you (from a while back in
> this email chain), but do you know if Tucker was looking at the recent
> upgrades to the ownership scheme?  Some of them may (or may not) be useful
> for Ada (if that gets implemented).  In particular, in the old ownership
> scheme, if you needed to use a throwaway variable to capture a return 
> result
> in Rust, you couldn't reborrow again until that throwaway variable went
> out of scope.  In the updated system, they are able to tell it is 
> throwaway
> and allow for the ownership transfer.  I was thinking about this for
> Ada particularly since we are required to capture function returns into
> some sort of variable.

I can't speak to what Tucker did or did not read about, but the latest 
approach uses a mix of compile-time and runtime checks to ensure that the 
owner really is the owner of the designated object. He has a number of 
examples using discriminants to carry the owner along at runtime (this is 
roughly how cursors already work in the Ada.Containers anyway, so it isn't a 
big change for them).

I'm pretty sure the SPARK people are only interested in static checks, for 
the obvious reason that they are only interested in static checks in 
general.

                      Randy.