Re: How to compile?

["Larry Loen" <lwloen@xxxxxxxxxx>]

Aaron Bartell asked:

>This is a theoretical question that I just came up with.

>How would I compile class A which utilizes class B and compile class B
that
>utilizes class A?  Since they use each other they wont compile until the
>other one is compiled.  I am figuring there must be a way out of this.

At least once this was not theoretical for me.  It can come up when a
parent class downcasts to a child.

What I have done is have a dummy version of the parent with all methods
present but with null implementations.  I compiled that, and then compiled
the child.  Only then can I compile the real parent.  (Or, was it dummy
child, compile parent, compile child; either would work, I would think).

Once you get things "bootstrapped" this way, there is a .class file out
there with the methods defined for the "other one".  For Java, this seems
to be enough to permit the compile; it doesn't do dependencies by source,
only by class file.  So, as long as there's a valid class file out there,
you ordinarily don't have to do it again, though I seem to recall having to
do this about three times, maybe when adding further children.


Larry W. Loen  -   Senior Java and AS/400 Performance Analyst
                          Dept HP4, Rochester MN


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