C++20 defer implementation, causes the provided code to be executed at the end of the scope... useful when working with C libraries that need things to be destroyed!

defer.hpp

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/* -----------------------------------------------------------------------------
	SYNTAX EXAMPLE
----------------------------------------------------------------------------- */
/*
	defer {
		// code here
	};

	Will defer the execution of the code until the end of the scope!

	Ex:
	{
		defer {
			std::cout << "This line will be displayed second" << std::endl;
		};
		std::cout << "This line will be displayed first" << std::endl;
	}
*/

// Defer (https://stackoverflow.com/questions/32432450/what-is-standard-defer-finalizer-implementation-in-c && https://www.gingerbill.org/article/2015/08/19/defer-in-cpp/)
#ifndef defer
#include <concepts>
#include <utility>
namespace detail {
	template <typename F>
	struct DeferImpl {
		F f;
		DeferImpl(F f) : f(f) {}
		~DeferImpl() { f(); }
	};
	struct ___defer_dummy___ {};
	template <std::invocable F> DeferImpl<F> operator<<(___defer_dummy___, F f) { return {std::move(f)}; }
}
#define DEFER_1(LINE) zz_defer##LINE
#define DEFER_2(LINE) DEFER_1(LINE)
#define DEFER_3 auto DEFER_2(__LINE__) = ::detail::___defer_dummy___{} << [&]()
#define defer DEFER_3
#endif // defer