Re: static variables in g++

From:
Frank Bergemann <FBergemann@web.de>
Newsgroups:
comp.lang.c++.moderated
Date:
Thu, 19 Jun 2008 20:36:45 CST
Message-ID:
<72e335c6-757b-4b7e-8be8-055e5fcbec46@56g2000hsm.googlegroups.com>
how about this - see below.
It is completely done by the compiler.
No inheritance, no constructors at runtime.

#include <iostream>
#include <string>

#include <boost/lexical_cast.hpp>
using boost::lexical_cast;

template <int FROM, int NO>
struct RangeUp {
    static std::string s;
};
template <int FROM, int NO>
std::string RangeUp<FROM, NO>::s (lexical_cast<std::string, int>(FROM)
+ " " + RangeUp<FROM+1, NO-1>::s);

template <int FROM>
struct RangeUp<FROM, 0> {
    static std::string s;
};
template <int FROM>
std::string RangeUp<FROM, 0>::s;

template <int FROM, int NO>
struct RangeDown {
    static std::string s;
};
template <int FROM, int NO>
std::string RangeDown<FROM, NO>::s (lexical_cast<std::string,
int>(FROM) + " " + RangeDown<FROM-1, NO-1>::s);

template <int FROM>
struct RangeDown<FROM, 0> {
    static std::string s;
};
template <int FROM>
std::string RangeDown<FROM, 0>::s;

template <int FROM, int TO>
struct Range {
    static std::string up;
    static std::string down;
    static std::string const& get() { return (FROM < TO) ? up : down; }
};
template<int FROM, int TO>
std::string Range<FROM, TO>::up (RangeUp< (FROM <= TO) ? FROM : 0,
(FROM <= TO) ? (TO - FROM + 1) : 0>::s);

template<int FROM, int TO>
std::string Range<FROM, TO>::down (RangeDown< (FROM >= TO) ? FROM : 0,
(FROM >= TO) ? (FROM - TO + 1) : 0>::s);

int main()
{
    std::cout << RangeUp<5,7>::s << std::endl;
    std::cout << RangeDown<99,10>::s << std::endl;
    std::cout << Range<5,10>::get() << std::endl;
    std::cout << Range<17,11>::get() << std::endl;
    std::cout << Range<5,5>::get() << std::endl;
         return 0;

}

rgds,
Frank

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