Re: assertions: does it matter that they are disabled in production?
On 2008-08-05 07:13, marlow.andrew@googlemail.com wrote:
Assertions via assert.h (or cassert) are disabled in production and
have to be enabled via the NDEBUG macro. This is one reason I don't
use the assert macro. I always throw an exception that means a fatal
programming error has occurred. Am I the only one that does this?
Surely not. My reasoning is that I always want the checks on, just in
case. This means it is something I tend to do sparingly, after all,
loads of them might well create a performance issue.
All the std programming text tell us how good it is to use assertions
(I am thinking of books like OOSC(II)) but the mechanism they describe
is like cassert every time, i.e turned off in production. I have
noticed that it is hardly ever used on any C++ projects I have seen.
It doesn't seem to get much use in C libraries either but does seem to
have a slightly higher usage there.
Does this mean C++ programmers don't like such a C-like mechanism? Or
they don't don't like the fact that the assertions are disabled in
production? Or is there some other reason?
Personally I have nothing against keeping the assertions in even in the
production code. After all if your code works correctly you will never
hit an assertion but if there are they can be very useful when the
customer reports the error.
The advantage of assertions it that they give you the file and line
where the error occurred for free. You can get the same information with
exceptions, and if you put some effort into it you can probably get a
stack trace also.
As for performance, I would not worry about it, after all you should
only assert things that are not supposed to happen and which can not
gracefully be handled. There should not be too many of these.
--
Erik Wikstr?m
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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