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From: steved@pacifier.com@199.2.117.163  (Steve Doiel)
Subject: Re: Exceptions:  Are they GOTOs?
Date: 1996/07/12
Message-ID: <4s4gic$etl@news.pacifier.com>#1/1
X-Deja-AN: 167909732
references: <brad.837052481@ss1>
organization: Pacifier BBS, Vancouver, Wa.  ((360) 693-0325)
reply-to: steved@pacifier.com  (Steve Doiel)
newsgroups: comp.lang.ada
Date: 1996-07-12T00:00:00+00:00
List-Id: <comp.lang.ada>


In <brad.837052481@ss1>, brad@cs.uwa.oz.au (Bradley Edelman) writes:
>What do people think about exception handling?  I believe it to be a major
>strength of Ada but there is a school of thought that exceptions are just
>GOTO statements and should be avoided accordingly.
>
>I think raising an exception is a neater way of handling an error than, say,
>returning an error code or status.
>
>I'd appreciate thoughts either way.
>
>Thanks, Brad

In my experience I have seen programs that don't have exceptions that bomb
mysteriously when something goes wrong.  It is common practice in C to
call calloc and not check the result, just use the allocated memory (I expect
a flame for that, but I have seen this in "professional" programs).

On my current project, I implemented exception handlers in C using setjmp and
longjmp and encapsulate all "calloc's" within exception handlers.  This will
not keep the program from bombing, but at least I'll know why so I can fix the
problem.

I've read a lot of "rules" of programming: "goto's are bad", "avoid tasking
where possible".  But what I've learned by experience is that these "rules"
are really guidelines.  What's it's really all about is making code that may
be easily understood and therefore easily maintained (which is why Ada is
usually a better choice than 'C').

In trying to read code, if every possible error condition is checked in line
it may involve nested if's that are hard to read.  When exceptions are used
the checks can be made directly where the errors might occur within reusable
components, and the normal flow of code may look very simple.

My opinion:
When code is easier to read is safer and easier to maintain.
Exceptions can make code easier to read.
Therefore exceptions are not bad.

(Of course you can misuse exceptions like anything else)

Steve Doiel