Re: [boost] [rfc] loop utility

Subject: Re: [boost] [rfc] loop utility
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2013-01-31 05:07:11

On Thu, Jan 31, 2013 at 1:58 PM, Thomas Heller <thom.heller_at_[hidden]> wrote:
> On 01/31/2013 10:31 AM, Tim Blechmann wrote:
>>
>> hi all,
>>
>> since c++11 has lambda functions, writing functors is easier than never
>> before ... so, i wonder, what do people think about a small utility
>> function, that calls a functor N times?
>>
>> ruby:
>> 10.times { puts 'hello world' }
>>
>> supercollider:
>> 10.do { "hello world".postln }
>>
>> c++11/boost proposal:
>> boost::loop(10, [] { printf("hello world\n"); });
>> boost::loop(10, [](int index) { printf("hello %d\n, index); });
>>
>>
>> personally, i find this coding style more elegant than for loops, as it
>> avoids the visual noise of explicitly counting a loop variable ... not
>> sure, if it is worth a separate library, maybe it could just be added to
>> boost/utility ...
>>
>> thoughts?
>
> This can already be done using the boost range library:
>
> ========8<========8<========8<========8<========8<========8<========
> #include <boost/range/irange.hpp>
> #include <boost/range/algorithm/for_each.hpp>
>
> int main()
> {
>    boost::for_each(boost::irange(0, 10), [] (int) { std::cout << "hello
> world\n";});
>    boost::for_each(boost::irange(0, 10), [] (int index) { std::cout <<
> "hello world from " << index << "\n";});
> }
> ========8<========8<========8<========8<========8<========8<========

IMHO, a regular loop looks simpler than either of these variants:

  for (int i = 0; i < 10; ++i)
    std::cout << "hello world from " << i << "\n";

also, I guess this should also work:

  for (auto i: boost::irange(0, 10))
    std::cout << "hello world from " << i << "\n";

We could add a new range generator to simplify this code even further
and remove the lower bound:

  for (auto i: boost::times(10))
    std::cout << "hello world from " << i << "\n";

where times(n) is equivalent to irange(0, n).