Re: new revision ada

[Wes Groleau <groleau+news@freeshell.org>]

Brian May wrote:
> compared with, say Java exceptions (as functions declare what
> exceptions they can raise, and can pass more information in the
> exception instead of just a string).

Well, a String can effectively carry ANY information.
But I agree Java is a little more flexible in exceptions.
However, the "throws" clause seemed like a good idea,
but turns out to be a major pain in large systems sometimes.

one example: Was getting a null pointer exception (can't
remember the Java name for that).  Took a long time to chase
down to two bugs.  When one class was fed the wrong file name,
instead of throwing file not found, it just acted like end-of-file
to another class.  And that class, not finding the item searched
for, returned a null pointer instead of an empty string for the
value.  Fixing the first bug by throwing FileNotFound required
chasing all over the (large) system adding in the throws clause
for it.

In Ada, when you add a raise at a low level, you only have to
add the handler.  You don't have to tweak every unit in the
call chain.

Moral of the story: One guy's relatively minor error
caused a heck of a lot of work for the other guy who
had to fix it.

-- 
Wes Groleau

He that complies against his will is of the same opinion still.
                   -- Samuel Butler, 1612-1680