Create example2.cpp

Author: Woon-2

example2.cpp

@@ -0,0 +1,123 @@
+#include <iostream>
+#include "smart_pointer_type_trait.hpp"
+
+template < typename Ptr >
+auto get_raw_pointer( Ptr& ptr )
+{
+	if constexpr ( std::is_pointer_v< Ptr > ) return ptr;
+	else return ptr.operator->();
+}
+
+template < typename Ty, typename Ptr >
+class pointer_impl
+{
+public:
+	void reset( Ty* target = nullptr )
+	{
+		if constexpr ( is_smart_ptr_v< Ptr > ) impl.reset( target );
+		else impl = target;
+	}
+
+	void release() { impl = nullptr; }
+
+	Ty* get() noexcept { return operator->(); }
+	const Ty* get() const noexcept { return operator->(); }
+
+	decltype( auto ) get_deleter() noexcept
+	{
+		static_assert( is_smart_ptr_v< Ptr >, "pointer_impl< Ty, Ptr >::get_deleter(): Ptr was not a smart pointer." );
+		return impl.get_deleter();
+	}
+	decltype( auto ) get_deleter() const noexcept
+	{
+		static_assert( is_smart_ptr_v< Ptr >, "pointer_impl< Ty, Ptr >::get_deleter(): Ptr was not a smart pointer." );
+		return impl.get_deleter();
+	}
+
+	Ty& operator*() noexcept { return *impl; }
+	const Ty& operator*() const noexcept { return *impl; }
+	Ty* operator->() noexcept { return get_raw_pointerr( impl ); }
+	const Ty* operator->() const noexcept { return get_raw_pointer( impl ); }
+	operator bool() const noexcept { return static_cast< bool >( get_raw_pointer( impl ) ); }
+
+	// special member functions
+	pointer_impl( Ty* impl = nullptr ) : impl{ impl } {}
+	~pointer_impl() { impl = nullptr; }
+
+private:
+	Ptr impl;
+};
+
+// ======================================================
+// ******************************************************
+// Decoupling by using keyword.
+// memory allocation policy has only-one dependancy, this code.
+// ======================================================
+template < typename Ty >
+using pointer = pointer_impl< Ty, std::unique_ptr< Ty > >;		// can change to diffrent pointer
+																// If you add more pointer object, ( and similar type trait )
+																// can also change to the pointer object.
+// ******************************************************
+// ======================================================
+
+template < typename Ty, typename ... Args >
+auto make( Args&& ... args )
+{
+	return pointer< Ty >{ new Ty{ std::forward< Args >( args )... } };
+}
+
+struct INT
+{
+	INT( int impl = 0 ) : impl{ impl } { std::cout << "INT constructor called\n"; }
+	~INT() { std::cout << "INT destructor called\n"; }
+	INT( const INT& other ) : impl{ other.impl } { std::cout << "INT copy constructor called\n"; }
+	INT& operator=( const INT& other )
+	{
+		if ( this != &other )
+		{
+			std::cout << "INT copy allocator called\n";
+			impl = other.impl;
+		}
+
+		return *this;
+	}
+	INT( INT&& other ) : impl{ other.impl } { std::cout << "INT move constructor called\n"; }
+	INT& operator=( INT&& other )
+	{
+		if ( this != &other )
+		{
+			std::cout << "INT move allocator called\n";
+			impl = other.impl;
+		}
+
+		return *this;
+	}
+	operator int() { return impl; }
+
+	int impl;
+};
+
+int main()
+{
+	std::cout << "must call constructor ==================\n";
+	auto a = make< INT >( 4 );
+	std::cout << "========================================\n\n\n";
+
+	std::cout << "get_deleter() call =====================\n";
+	std::cout << typeid( a.get_deleter() ).name() << '\n';
+	std::cout << "========================================\n\n\n";
+	
+	std::cout << "print value ============================\n";
+	std::cout << "value: " << *a << '\n';
+	std::cout << "========================================\n\n\n";
+	
+	std::cout << "must call constructor and destructor ===\n";
+	a.reset( new INT{ 5 } );
+	std::cout << "========================================\n\n\n";
+
+	std::cout << "print value ============================\n";
+	std::cout << "value: " << *a << '\n';
+	std::cout << "========================================\n\n\n";
+
+	std::cout << "must call destructor ===================\n";
+}