Re: [boost] [Range] New I/O functions for ranges

Subject: Re: [boost] [Range] New I/O functions for ranges
From: Indiana (indi.in.the.wired_at_[hidden])
Date: 2014-10-05 11:46:43

On 14-10-01 05:00 AM, Paul A. Bristow wrote:
> You may well be right, but I'm only reporting what I found were my 'needs'.
>
> You can show how to wrap write_all output (with 'smart' delimiter - no ugly
> trailing commas!) with prefix and suffix strings, that will probably be fine.
Yeah, sure - actually write_all() does that right out of the box:

o << "prefix" << write_all({1,2,3}, "delimiter") << "suffix";
// Prints: "prefix1delimiter2delimiter3suffix";

So:

o << '{' << write_all({1,2,3}, ',') << '}';
// Prints: "{1,2,3}"
> I only meant a string in C++ syntax like
>
>    int[10] = {1,  2,  3,  4,  5,  6,  7,  8,  9,  10};
>
> that you have shown is possible.
Actually, you can probably generalize that. The following code isn't 
tested, but:

template <typename Range, typename CharT, typename Traits>
void format_range(std::basic_ostream<CharT, Traits>& o, Range&& r)
{
   using std::begin;
   using std::end;
   using value_type = std::decay_t<typename range_value<Range>::type>;

   std::basic_ostringstream<CharT, Traits> oss{};
   oss.imbue(std::locale::classic());

   oss << boost::typeindex::type_id<value_type>().pretty_name();
   oss << '[' << std::distance(begin(r), end(r)) << ']' << " = ";
   oss << '{' << write_all(std::forward<Range>(r), ", ") << "};\n";

   o << oss.str();
}

Calling format_range() for any range type should give the output you 
want, more or less, dependent on the range value type.

auto v = std::vector<int>{1,2,3};
cout << format_range(v); // Prints: "int[3] = {1, 2, 3};"
auto const a = std::array<double, 4>{1.1, 2.2, 3.3, 4.4};
cout << format_range(a); // Prints: "double[4] = {1.1, 2.2, 3.3, 4.4};"
> Now you need some enthusiastic users to support you on a review ;-)
Yeah? I'm not sure how the process goes here. Do I make a pull request 
on the Boost.Range repository and implement the changes? Or do I 
implement the idea separately, so people can experiment and mess around 
with it, and only after it's passed review try to integrate it with the 
rest of the library? Do I get in touch with the Boost.Range maintainers 
(seems to be Thorsten Ottosen and Neil Groves)?