Re: Extending a third party tagged type while adding finalization

[Jere <jhb.chat@gmail.com>]

On Monday, November 27, 2017 at 8:55:19 PM UTC-5, Randy Brukardt wrote:
> "Jere" wrote in message 
> ...
> >> Based on what I have read so far, I didn't see any discussion that would
> >> lead me to think this will be changed at least in the near future.  I
> >> wish there was a way it would be easy for vendors to do something like:
> >>
> >> type Some_Type is tagged private;
> >> for Some_Type'Initialize use Initialize_Some_Type;
> >> for Some_Type'Adjust use Adjust_Some_Type;
> >> for Some_Type'Finalize use Finalize_Some_Type;
> >>
> >> and then just have the compiler handle adding the needed structures
> >> to the type under the hood (like how GNAT uses Controlled to hold
> >> a linked list under the hood...but compiler managed).
> 
> The only way this could be made to work in Janus/Ada would be for all tagged 
> types to be controlled, which would waste time and space for types that 
> aren't actually controlled. Since Janus/Ada was designed to be 
> space-efficient, that would be going directly against our primary goal - not 
> something I'd do without a fight.
> 
>                                             Randy.

Well, I am definitely not advocating that all tagged types need to be
controlled.  I was just musing about whether there was a different way
to do it.  The Ada Finalization method is very clunky and can be
limiting at times.  There may not be a better way to do it.  At the
end of the day, I find a lot of the errors our programmers make is
forgetting to put in a Create/Intialize or Clean_Up/Finalize call 
on objects that do not have Controlled ancestors.  It's a 
maintenance headache, so I look for ways to try to remedy that via 
design.