Re: Separate Compilation in Programming Languages

[<adaworks@sbcglobal.net>]

"Ray Blaak" <rAYblaaK@STRIPCAPStelus.net> wrote in message 
news:ulk58of6r.fsf@STRIPCAPStelus.net...
> Ray Blaak <rAYblaaK@STRIPCAPStelus.net> writes:
>> > Perhaps.  But I still don't see how one can defer the dependency of a
>> > Java signature to the implementation of the Java class and prevent
>> > the need for recompiling the entire architecture when the signature of
>> > a parent class changes.
>>
>> Maybe the disconnect is here. Are you talking about how spec changes ripple
>> down, or are you talking about how body changes ripple down? Spec changes
>> affect clients and bodies, both in Java in Ada. Body (implementation) do not
>> affect clients that only refer to the spec, both in Java and Ada.
>
> It also occurs to me to wonder if you were assuming the Java interface and
> implementation are in the same file. If so, the issues you say would indeed
> happen.
>
> But usually the interface and its implementations are in separate files, as
> per the usual Java rule of one class per file. That separation is what allows
> Java to have separate compilation.
>
But only for Interface-based designs.   Further, the implementation of the
Interface, with its extended signature is in the same file with the algorithmic
code.  This is significantly different from how we design in Ada where the
implementation code (package body) is kept separate from the specification.
Also, if the signature of the Interface changes, everything dependent on that
signature will also have to change.   And everything dependent on that
Interface implementation will have to change.  The ripple-effect will occur
since most of a Java design is not based on Interfaces, and that is the
problem with inability to defer dependencies as we can in Ada.

Richard Riehle
> -- 
> Cheers,                                        The Rhythm is around me,
>                                               The Rhythm has control.
> Ray Blaak                                      The Rhythm is inside me,
> rAYblaaK@STRIPCAPStelus.net                    The Rhythm has my soul.