Re: Exception Misconceptions
On 19 Dec, 21:42, ta...@mongo.net (tanix) wrote:
In article
<668a7a4b-a2ee-4999-b3bc-5020bdac1...@k4g2000yqb.googlegroups.com>,
James Kanze <james.ka...@gmail.com> wrote:
[...]
Similarly, with regards to optimizing application code:
you've only got so much time to write it in, so it's often a
question of making it take 5 milliseconds less time (over an
hour), or adding a feature.
Well, to me, optimization is indeed one of the major criteria,
except I view optimization from the stand point of
architecture.
There are different ways to structure your code, or architect
the system.
The major criteria for me are:
1) Minimization of the size of executable,
which indirectly translates into correctness of your code and
flexibility of your structure and program architecture.
That's interesting, because memory use is one of the big costs
for garbage collection. I've actually used garbage collection
in C++ at times, and I know how to write C++ code which uses the
Boehm collector, but for the application you described
else-thread, I wouldn't do it, because the memory overhead of
garbage collection is just too high (and because for that
particular problem, garbage collection just doesn't buy you that
much anyway).
4) Portability.
A tough one. Forget about it in the C++ world.
Such a major headache, that it is realistically undoable
unless you maintain several code bases.
With Java - a pice o cake. Non issue.
My experience is exactly the opposite. Java's portability is
limited to machines which have a good JVM. Which isn't many.
C++ works on pretty much everything.
5) Robustness.
And THAT is where these nasty exceptions come in handy.
You'll never be able to write a stable code, and I mean TRULY
stable, if you do not use exceptions.
Explain how applications have been running for years, without
interruption, and without using exceptions. (The application in
question was written before C++ supported exceptions.)
Exceptions are a useful tool, for certain things, but like all
tools, you can do without (at some development cost) if you have
to.
[...]
So, exceptions should not be a part of your underlying logic.
They are your defense system against ANY kinds of problems.
You can NEVER assume that ANY operation is going to complete
without problems. In the middle of some routine, you may
loose power, just for the sake of argument.
In which case, you won't be able to process an exception.
That means, that once you restart your program, and it was in
the middle of doing some heavy duty processing, you should be
able to recover and continue on, if at all possible, even in
principle.
So you need persistent transactions. You're not the first
person to need them, and a lot of applications use them,
including applications written long before anyone had ever heard
of exceptions.
[...]
I think all really competent computer scientists are purists,
Good. Keep them in museums then.
Nothing like taking a quote out of context, is there?
--
James Kanze