[Boost-users] begin (cout) or boost::copy to cout

Subject: [Boost-users] begin (cout) or boost::copy to cout
From: Krzysztof Żelechowski (giecrilj_at_[hidden])
Date: 2011-09-13 17:35:06

== The Problem ==

Boost.Range defines boost:: begin to give you the iterator to every possible 
container — except ostream.

== Solution 1 ==

=== Implementation ===

I have the following function for you to add to Boost.Range:

template < class P_I, class P_C, class P_T > 
std:: ostream_iterator 
< typename boost:: iterator_value < P_I >:: type, P_C, P_T > 
begin 
(std:: basic_ostream < P_C, P_T > &p_s, P_I const &, 
P_C const p_p [] = NULL) 
{ 
return 
std:: ostream_iterator 
< typename boost:: iterator_value < P_I >:: type, P_C, P_T > (p_s, p_p); }

=== Application ===

to be used in the following way:

void foo (std:: vector < int > const &v) 
{ boost:: copy (v, boost:: begin (std:: cout, boost:: begin (v), " "); }

This function eliminats the need of passing explicit template parameters to 
std:: ostream_iterator, which makes the code fragile and hard to read.

== Solution 2 ==

=== Motivation ===

Since an output stream iterator is not useful except for copying to an 
output stream, a further simplification is also possible:

=== Implementation ===

template < class P_R, class P_C, class P_T > 
std:: basic_ostream < P_C, P_T > 
&copy 
(P_R const &p_r, std:: basic_ostream < P_C, P_T > &p_s, 
P_C const p_p [] = NULL) 
{ 
copy 
(p_r, 
std:: ostream_iterator 
< typename boost:: range_value < P_R >:: type, P_C, P_T > (p_s, p_p)); 
return p_s; }

=== Application ===

and it enables the following invocation:

void foo (std:: vector < int > const &v) 
{ boost:: copy (v, std:: cout, " "); }

Please consider.

Chris