Re: Separate Compilation in Programming Languages

[<adaworks@sbcglobal.net>]

"Ray Blaak" <rAYblaaK@STRIPCAPStelus.net> wrote in message 
news:u3arjcxx3.fsf@STRIPCAPStelus.net...
> <adaworks@sbcglobal.net> writes:
>> Even with an interface, a la Java, once the interface is implemented, the
>> children dependent on that unit will be dependent on the implementaion,
>> not on the interface.
>
> This is not true. I can show you code if you are interested.
>
I think I was not clear.   When a specification (interface, package 
specification,
etc.) remains stable, the implementation is not as much of a factor as changes
in the specification.   When one specification is dependent on another, a change
to the parent specification will require recompiling all of the dependent
specifications.   When the effect of the specification is deferred to the 
implementation
level, none of the other specifications should have to be compiled.   This is 
quite
easy to do in Ada.

When the dependencies are deferred to the implementation module (an Ada
package body) a change to a parent specification requires only that body to
be recompiled.   When the specification is at the level of another 
specification,
and a change is made to a higher level unit, everything needs to be recompiled.

I think this is as true of Java as it is of Ada.   The only difference is that 
Ada allows
one to defer the dependency to the package body.   This does not seem to be
true of Java.   I hope I am more clear.   If not, perhaps someone can state it 
more
clearly than I since it is a pretty simple idea.

Richard Riehle