Re: Separate Compilation in Programming Languages

[Ray Blaak <rAYblaaK@STRIPCAPStelus.net>]

<adaworks@sbcglobal.net> writes:
> 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.

No, not necessarily. It is quite possible that the only an implementation was
client of the changed spec, and that the change's effects do not perculate
out. That is, the change is not transitive.

> 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. 

The deferral to a package body is precisely equivalent to the deferral to
another implementation class. The implementation class is (or can be) private,
hidden in exactly the same way the body of a package is.

That is what allows Java interfaces to serve as equivalent controls for
separate compilation as Ada's package bodies. Mind you, they're not
necessarily as convenient, mind you, but I am objecting only to the notion
that Java does not support separate compilation.

-- 
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.