Hi Gilles,
On 09/04/2012 06:48 PM, Gilles Sadowski wrote:
Hello.
There are ideas that sound good we experiment with them within a limited
framework (like a course on programming, for example); and then become a
nightmare when you find yourself constantly trying to get around them.
I mean that a design idea might look nice, and only when you are long way
into implementing the consequences of that idea, you discover that it was
not such a good one after all.
Been there :)
As a user of commons math I think it would be great if a each exception
mapped to a "One of a kind problem". So instead of having a
NegativeIntegerException, which is generic and could be used in a lot
of places, have SuperDuperOptimizerNegativeIntegerException, which is
only thrown in one place.
Is this possible?
Possible, it is. But have you imagined how many different exceptions that
would entail?
I really did and thought maybe this is just crazy.
Currently, there are more than 1000 "throw" statements in CM.
My position is to have a mapping between "exception type" and "problem
kind"; your suggestion looks like a mapping between "exception type" and
"problem location".
I would rephrase my suggestion as a mapping between "exception type" and
"solution". So if you know the exception type, you immediately know how to provide
options to the person responsible for the operation.
Besides the drawback of an enormous increase of the number of classes, tying
the exception to its place of use is redundant with the information already
provided in the stack trace.
I agree. I really meant "Solution". It seems that we are already at the point
where exceptions should provide parameters from the instance that threw the exception for
the purpose of UI display, logging, etc., so if it's going to be that specific, then why
not make it so specific that it can only have one possible message and one set of
solutions specific to the context.
[One of the most useful rules in programming is code reuse; it would be a
waste of a programmer's time to create a new exception class just because
it is intended to be thrown from a different place.]
I agree.
The main reason I threw my 2 cents in is because it seem like the design of the
exceptions was getting very complicated with the inclusion of localization,
unrolling of diagnostic contexts (Not sure if I said that right...), etc. and
there has to be a simpler way.
For example it seems like localization should be worried about after you catch
the exception and you know what to do with it. I like that localization is
part of commons math, but to me it seems that it should be a utility that can
be used for message display once an action has been decided upon post catching
the exception. Right now it seems that localization has become a constraint on
exception design.
Cheers,
- Ole
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