id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
4397	specialization for lexical_cas for identical Target and Source types	alexey.kutumov@…	Antony Polukhin	"std::string s1 = ""str"";
std::string result = boost::lexical_cast<std::string>(s1);

In this case it is possible to use specialization of lexical_cast which just returns input arg.

I created simple example with specialization of lexical_cast:


{{{
#include <boost/cstdint.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/type_traits.hpp>
#include <iostream>

template <typename Target, typename Source, bool val> struct helper
{
	/// Default action is to use lexical_cast
	static Target get(const Source & src)
	{
		return boost::lexical_cast<Target>(src);
	}
};

template <typename Target, typename Source> struct helper<Target, Source, true>
{

	/// Use this if Target and Source identical
	static Target get(const Source & src)
	{
		return src;
	}
};

template <typename Target, typename Source> Target my_lexical_cast(const Source & res)
{
	/// Use boost::is_same for checking identity of Target and Source
	return helper<Target, Source, boost::is_same<Target, Source>::value>::get(res);
}

int main(int argc, char * argv[])
{
	std::string b1 = ""10"";

	std::string b2 = my_lexical_cast<std::string>(b1);
	int b3 = my_lexical_cast<int>(b1);

	std::cout << ""b1: "" << b1 << std::endl;
	std::cout << ""b2: "" << b2 << std::endl;
	std::cout << ""b3: "" << b3 << std::endl;

	return 0;
}
}}}



This code checked in msvc 9.0, mingw32-g++ 4.4.0
"	Feature Requests	closed	Boost 1.44.0	lexical_cast	Boost 1.44.0	Optimization	fixed	lexical_cast specialization	alexey.kutumov@…