Re: std::for_each + break

From:

alan <almkglor@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Tue, 20 Nov 2007 13:27:34 -0800 (PST)

Message-ID:

<c66fcc63-77a7-4841-9d7a-fdce892f01e5@a39g2000pre.googlegroups.com>

On Nov 21, 4:51 am, Kira Yamato <kira...@earthlink.net> wrote:

On 2007-11-20 04:45:36 -0500, Kai-Uwe Bux <jkherci...@gmx.net> said:

Kira Yamato wrote:

On 2007-11-19 07:12:29 -0500, yurec <Yurij.Zha...@materialise.kiev.ua>
said:

Hi

I wanna give template method of library class with some predicate,
which I put to std::for_each in that method.How to break the
std::for_each with predicate?(exceptions are used olny in exceptional
situations, as i know)

Thanks

I would think throwing an exception is a simple and elegant solution here.

Simple and elegant? in this case?

Compare

  try {
    std::for_each( seq.begin(), seq.end(), throwing_predicate_and_action );
  }
  catch ( whatever ) {}

to

  for ( iterator_type iter = seq.begin();
        iter != seq.end() && ! break_condition( *iter );
        ++iter ) {
    some_action( *iter );
  }

I cannot say that I find the try-throw-catch version easier to grok or more
elegant.

Hmm. The for-loop code looks more explicit than the for_each. So, why
do we bother with for_each again?

So we won't have to bother with iterators, which are just pointers in
pretty clothes?

Or I should ask, why would we ever prefer a statement over a block?

[...]

--

-kira