Re: min and max running values

From:

Pete Becker <pete@versatilecoding.com>

Newsgroups:

comp.lang.c++

Date:

Tue, 06 Mar 2007 14:20:05 -0500

Message-ID:

<7uqdnU8pYNp7I3DYnZ2dnUVZ_uvinZ2d@giganews.com>

Clark Cox wrote:

On 2007-03-06 09:08:27 -0800, Pete Becker <pete@versatilecoding.com> said:

Clark Cox wrote:

On 2007-03-05 20:08:44 -0800, Ron House <house@usq.edu.au> said:

You cannot have a well-defined max or min of zero items. So read the
first value, check that you can get that first value and complain
somehow (err message, exception, etc.)

OK, so you check for error on reading the first value; do you then do
zero error checking on the second and subsequent values? No, you
*repeat the same error checking* (or a subset thereof); leading to
redundant code, which adds unneeded complexity and increases the
maintainence burden.

Maybe. But it's also reasonable to simply say that calling a function
that returns the minimum value in a range of values with an empty
range produces undefined behavior. Implementations can check if they
want to, but aren't required to do anything sensible. After all,
asking for the minimum of no values is not a sensible request.

std::min_element seems to think that it is a perfectly sensible request,
with a well-defined return value.

Yes, because min_element takes iterators and follows the conventions of
STL algorithms. There are other ways to design functions, and in the
absence of any requirements, it's not possible to decide whether one
approach is better than another.

--

-- Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com)
Author of "The Standard C++ Library Extensions: a Tutorial and
Reference." (www.petebecker.com/tr1book)