Re: C++ Ranges proposal for the Standard Library

[Olivier Grant via Digitalmars-d]

On Friday, 17 October 2014 at 09:52:26 UTC, Marco Leise wrote:

Am Fri, 17 Oct 2014 09:17:51 +0000
schrieb "ZombineDev" <valid_em...@he.re>:

I saw [this][0] proposal for adding ranges to C++'s standard
library. The [paper][1] looks at D style ranges, but concludes:

> Since iterators can implement D ranges, but D ranges cannot > be used to implement iterators, we conclude that iterators > form a more powerful and foundational basis.

What do you guys think?

[0]: https://isocpp.org/blog/2014/10/ranges
[1]: https://ericniebler.github.io/std/wg21/D4128.html

True. Iterators are more foundational, ranges are more
neat-o. ;)
When you look at this C++ function as part of a signal
processing home work you know why you don't want to see them
in top level code:

// C++

double mittelwert(const vector<double>& vektor)
{
        vector<double>::const_iterator it;
        double summe = 0;
        for (it = vektor.begin(); it != vektor.end(); ++it)
        {
                summe += *it;
        }
        return summe / vektor.size();
}

// D (removing iterators)

double mittelwert(in double[] vektor)
{
        double summe = 0;
        foreach (wert; vektor)
        {
                summe += wert;
        }
        return summe / vektor.length;
}

// D (using range sum function)

double mittelwert(in double[] vektor)
{
        return sum(vektor) / vektor.length;
}

No, the equivalent implementation in C++ is this:

double mittelwert(const vector<double>& vektor)
{
   double summe = 0;

   for(auto &x : vektor)
   {
      summe += x;
   }

   return summe / vektor.size();
}