Simple traits demo for sub-arithmetic types

.gitignore

*.o
main

main.cc

#include "traits.hh"

#include <iostream>

typedef Thin< std::size_t > Bound;

int main()
{
    for (Bound thin(0); thin != Bound(10); ++thin)
    {
        std::cout << "a line\n";
    }
}

Makefile

CXXFLAGS += -Wall -Wextra -Werror -pedantic-errors
CXXFLAGS += -O3

LINK.o = $(LINK.cc)

all: main

main.o: traits.hh

clean:
	$(RM) main *.o

traits.hh

template< typename Self, typename T, typename Base, T Base::* Member >
struct Preincrements
{
    Self & operator ++ ()
    {
        Self & self = static_cast<Self &>(*this);
        ++(self.*Member);
        return self;
    }
};

template< typename Self, typename T, typename Base, T Base::* Member >
struct Eq
{
    bool operator == (Self const & that)
    {
        Self & self = static_cast<Self &>(*this);
        return self.*Member == that.*Member;
    }

    bool operator != (Self const & that)
    {
        return !(*this == that);
    }
};

template< typename Self, typename T, typename Base, T Base::* Member >
struct PartialOrd
{
    bool operator < (Self const & that)
    {
        Self & self = static_cast<Self &>(*this);
        return self.*Member < that.*Member;
    }
};

template< typename T >
struct Base
{
    T member;
    explicit Base(T const & in)
        : member(in)
    {
        // no body
    }
};

template< typename T >
class Thin
    : public Base< T >
    , public Preincrements< Thin< T >, T, Base< T >, &Base< T >::member >
    , public Eq< Thin< T >, T, Base< T >, &Base< T >::member >
    , public PartialOrd< Thin< T >, T, Base< T >, &Base< T >::member >
{
private:
    // Privatize a member inherited publicly
    // Public inheritance simplifies the trait code significantly
    using Base< T >::member;
public:
    explicit Thin(T const & in)
        : Base< T >(in)
    {
        // no body
    }
};