Simplified to_string definition

Author: zajo

doc/qvm.adoc

@@ -394,8 +394,6 @@ QVM is split into multiple headers to allow different compilation units to `#inc
 
 The tables below list commonly used components and the headers they're found in. Header names containing a number define functions that only work with objects of that dimension; e.g. `vec_operations2.hpp` contains only functions for working with 2D vectors.
 
-The header `boost/qvm/to_string.hpp` must be included before calling any `to_string` overload defined in namespace `boost::qvm`.
-
 The header `boost/qvm/all.hpp` is provided for convenience. It includes all other QVM headers.
 
 In addition, Boost QVM is available in single-header format for maximum portability. See <<Distribution>>.
@@ -2805,8 +2803,6 @@ namespace boost { namespace qvm {
 
 Returns: :: A string representation of the value of `a`, in unspecified format.
 
-NOTE: Calling any `to_string` overload defined in the `boost::qvm` namespace requires `#include <boost/qvm/to_string.hpp>`.
-
 '''
 
 [[qref]]
@@ -3391,8 +3387,6 @@ namespace boost { namespace qvm {
 
 Returns: :: A string representation of the value of `a`, in unspecified format.
 
-NOTE: Calling any `to_string` overload defined in the `boost::qvm` namespace requires `#include <boost/qvm/to_string.hpp>`.
-
 '''
 
 [[vref]]
@@ -4514,8 +4508,6 @@ namespace boost { namespace qvm {
 
 Returns: :: A string representation of the value of `a`, in unspecified format.
 
-NOTE: Calling any `to_string` overload defined in the `boost::qvm` namespace requires `#include <boost/qvm/to_string.hpp>`.
-
 '''
 
 [[mref]]

include/boost/qvm/lite.hpp

@@ -4,6 +4,7 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
 #include <boost/qvm/error.hpp>
+#include <boost/qvm/to_string.hpp>
 #include <boost/qvm/mat_operations.hpp>
 #include <boost/qvm/mat_access.hpp>
 #include <boost/qvm/mat_traits_defaults.hpp>
@@ -25,4 +26,3 @@
 #include <boost/qvm/vec_mat_operations.hpp>
 #include <boost/qvm/vec_register.hpp>
 #include <boost/qvm/map.hpp>
-#include <boost/qvm/to_string.hpp>

include/boost/qvm/mat_operations.hpp

@@ -16,7 +16,7 @@
 #include <boost/qvm/detail/cofactor_impl.hpp>
 #include <boost/qvm/detail/transp_impl.hpp>
 #include <boost/qvm/scalar_traits.hpp>
-#include <string>
+#include <boost/qvm/to_string.hpp>
 
 namespace boost { namespace qvm {
 
@@ -34,12 +34,6 @@ qvm_detail
 
 ////////////////////////////////////////////////
 
-namespace
-qvm_to_string_detail
-    {
-    template <class T>
-    std::string to_string( T const & x );
-    }
 
 namespace
 qvm_detail

include/boost/qvm/quat_operations.hpp

@@ -14,8 +14,7 @@
 #include <boost/qvm/assert.hpp>
 #include <boost/qvm/error.hpp>
 #include <boost/qvm/throw_exception.hpp>
-#include <string>
-#include <cmath>
+#include <boost/qvm/to_string.hpp>
 
 namespace boost { namespace qvm {
 
@@ -44,12 +43,6 @@ msvc_parse_bug_workaround
         };
     }
 
-namespace
-qvm_to_string_detail
-    {
-    template <class T>
-    std::string to_string( T const & x );
-    }
 
 template <class A>
 inline

include/boost/qvm/to_string.hpp

@@ -6,13 +6,17 @@
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
-#if __cplusplus >= 201103L
-
 #include <string>
 
+#if __cplusplus >= 201103L
+
 namespace boost { namespace qvm {
 
-namespace qvm_to_string_detail = std;
+namespace
+qvm_to_string_detail
+    {
+    using std::to_string;
+    }
 
 } }
 

include/boost/qvm/vec_operations.hpp

@@ -13,7 +13,7 @@
 #include <boost/qvm/vec_operations4.hpp>
 #include <boost/qvm/assert.hpp>
 #include <boost/qvm/scalar_traits.hpp>
-#include <string>
+#include <boost/qvm/to_string.hpp>
 
 namespace boost { namespace qvm {
 
@@ -31,12 +31,6 @@ qvm_detail
 
 ////////////////////////////////////////////////
 
-namespace
-qvm_to_string_detail
-    {
-    template <class T>
-    std::string to_string( T const & x );
-    }
 
 namespace
 qvm_detail