Re: Question on vector at()
On Mar 17, 12:51 am, Juha Nieminen <nos...@thanks.invalid> wrote:
Jeff Schwab wrote:
I can't think of many applications where at() throwing an exception
would be in any way a desirable thing. (As mentioned, to catch
programming errors IMO using assert() is better.)
Huh? The exception is *exactly* the right solution, for the
reasons red floyd already explained.
Could you please explain to me why is that?
If indexing out of boundaries at some place is an indication
of a programming error, ie. a bug, the best course of action
is to report immediately about this detected error, at the
place where it happens. assert() is exactly the tool designed
for this: It terminates the program immediately, and with the
aid of a debugger you can see the whole stack trace and the
values of the variables exactly when the error happened. This
way the programming error can be fixed, and the indexing out
of boundaries will not happen anymore.
Note that even without the possibilities of a debugger...
[...]
The only advantage of throwing an exception is that the
program could, if so designed (which is often *very*
laborious), continue without interruption. However, what would
the program do in that case? A bug has been detected, and now
the program knows that function is flawed, the data is
incorrect, and nothing that function returned can be relied
on. That buggy function is completely useless. What exactly
is the right course of action in this case? (And how does it
differ from a simple assert?)
That's the key point. If you can't count on doing anything
correct, the only course of action is not doing anything,
quickly and noisily, so that whatever back up systems are
available can take over. (The "back up system" might be as
simple as a human being deciding that we'll have to do without
that functionality for the moment.)
--
James Kanze (GABI Software) email:james.kanze@gmail.com
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