Created
November 16, 2013 07:28
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#include <iostream> | |
#include <tuple> | |
namespace | |
{ | |
template<typename T> | |
using identity = T; | |
template<typename T, typename... V> | |
struct RAII_Set_impl | |
{ | |
T &t; | |
std::tuple<identity<V T::*>...> mop; | |
std::tuple<V...> ds; | |
RAII_Set_impl(T &t_, std::tuple<V T::*, V, V>... sets) | |
: t(t_) | |
, mop(std::get<0>(sets)...) | |
, ds(std::get<2>(sets)...) | |
{ | |
set(std::get<1>(sets)...); | |
} | |
~RAII_Set_impl() | |
{ | |
unset(typename gens<sizeof...(V)>::type()); | |
} | |
template<typename... U> | |
void set(U... u) | |
{ | |
do_set<0, U...>(u...); | |
} | |
template<std::size_t i, typename First, typename... Rest> | |
void do_set(First first, Rest... rest) | |
{ | |
t.*std::get<i>(mop) = first; | |
do_set<i+1, Rest...>(rest...); | |
} | |
template<std::size_t i, typename Last> | |
void do_set(Last last) | |
{ | |
t.*std::get<i>(mop) = last; | |
} | |
template<std::size_t i> | |
void do_set() | |
{ | |
} | |
template<std::size_t...> struct seq{}; | |
template<std::size_t N, std::size_t... S> | |
struct gens : gens<N-1, N-1, S...> {}; | |
template<std::size_t... S> | |
struct gens<0, S...> | |
{ | |
using type = seq<S...>; | |
}; | |
template<std::size_t... S> | |
void unset(seq<S...>) | |
{ | |
set(std::get<S>(ds)...); | |
} | |
}; | |
template<typename T, typename... V> | |
auto RAII_Set(T &t, std::tuple<V T::*, V, V>... sets) | |
-> RAII_Set_impl<T, V...> | |
{ | |
return RAII_Set_impl<T, V...>(t, sets...); | |
} | |
} | |
struct Test | |
{ | |
int x, y; | |
double z; | |
~Test() | |
{ | |
std::cout << "x = " << x << std::endl | |
<< "y = " << y << std::endl | |
<< "z = " << z << std::endl; | |
} | |
} t; | |
int main() | |
{ | |
auto raii_set_t = RAII_Set(t, | |
std::make_tuple(&Test::x, 1, 2), | |
std::make_tuple(&Test::y, 3, 4), | |
std::make_tuple(&Test::z, 5.5, 6.6) | |
); | |
std::cout << "x = " << t.x << std::endl | |
<< "y = " << t.y << std::endl | |
<< "z = " << t.z << std::endl; | |
std::cout << std::endl; | |
} |
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