Re: any_of, all_of, none_of

From:
=?ISO-8859-1?Q?Daniel_Kr=FCgler?= <daniel.kruegler@googlemail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Thu, 25 Aug 2011 05:26:42 -0700 (PDT)
Message-ID:
<j33e5v$pq0$1@dont-email.me>
Am 24.08.2011 03:49, schrieb gast128@hotmail.com:

Hello all,

I was wondering why the c++ committee didn't decide to stick to the
'_if' convention as used in other STL algorithm, like all/all_if,
any / any_if etc.


In principle that would have been possible, but the request of
any/all/none is already so fundamental, that the absence of an explicit
customization point (the predicate) makes a further reduction hard to
argue for.

These new algorithms seems only be defined for use with predicates.
But what if u just want to use these for testing against a value, you
now have to bind an argument to an equal_to structure. Or perhaps this
can be easier done?

void f()
{
     std::vector<int> vec(1, 3);

     const bool bAny = std::any_of(vec.begin(), vec.end(),
boost::bind(std::equal_to<int>(), _1, 3));
     _ASSERT(bAny);
}


Just use a lambda expression instead:

void f()
{
     std::vector<int> vec(1, 3);

     const bool bAny = std::any_of(vec.begin(), vec.end(),
      [](int value) { return value == 3; });
     _ASSERT(bAny);
}

HTH & Greetings from Bremen,

Daniel Kr?gler

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