Re: Where shoul I throw RuntimeException
Giovanni Azua wrote:
Hello Eric,
"Eric Sosman" <Eric.Sosman@sun.com> wrote in message
Thought experiment: Should the array-accessing operation treat
the index value as an input to be validated, or as a precondition
whose validity has been established during the testing phase and
need not be checked thereafter? That is, would you be in favor of
checking indices with an assert-like mechanism that could be turned
off once the code had passed enough tests? Surely it's a programming
error if the code generates an invalid index; should the detection
of that error be suppressable?
To be honest I'd personally prefer to spare all the worthless and expensive
validations and hence the [substantial?] performance overhead resulting from
this Defensive Programming approach when I know my code is throughly tested.
I really prefer here the C++ way, they assume you know what you are doing.
On the other hand, If you know your Java code is not well tested then you
would still have the choice to run it -ea in production ... though it would
be a very lame acknowledgement.
Checking array indices for validity is "worthless?"
Testing can prove code to be bug-free?
How long was the voyage from your planet?
Your distinction between validation and precondition checking
is, I think, a reasonable one to draw in private and package-
private methods. But a public or protected method is too "exposed"
to take advantage of such a distinction, and should IMHO treat all
inputs as coming from "the outside."
I believe this is a decision of the API or public method designer to make,
of whether the API in question is supposed to be exposed to "the outside" or
not.
If the API is not to be exposed, it has to be private or at the
very least package-private. Anything that's public or protected *is*
exposed, and there's no way to prevent or even limit the exposure.
Yes, the designer has the freedom to choose the level of exposure he
thinks is appropriate -- but if he tags a method as `public', he's
voted for wide-open exposure and should code accordingly.
--
Eric.Sosman@sun.com