Go-like defer statement (C++11)

defer.cc

/**
 * Go-like defer statement (C++11)
 *
 * g++ --std=c++0x -o def def.cc
 *
 * also see http://blog.korfuri.fr/post/go-defer-in-cpp/
 */

#include <functional>
#include <iostream>

#define DEFER_UQ(A, UQID) defer defr_ ##UQID ([]{ A;});
#define DEFER_CALL(A, UQ)   DEFER_UQ(A, UQ)
#ifdef __COUNTER__
#define DEFER(A) DEFER_CALL(A, __COUNTER__)
#else
#define DEFER(A) DEFER_CALL(A, __LINE__)
#endif

class defer {
        std::function<void()> t;
    public:
        defer(std::function<void()> &&t) : t(t) {}
        ~defer() { t(); }
};

int main() {
    defer d([]{ std::cout << " world!!" << std::endl; });
    DEFER(std::cout << "... and again" << std::endl)
    DEFER(std::cout << "... plus once more." << std::endl)
    std::cout << "Hello";
}

Awful for efficiency - std::function<> does type erasure via heap allocations. Salty syntax.