C++ Utility for accessing private members

Rob.h

/*
 * Copyright 2022 Marcin Swiderski
 * 
 * The MIT Licence (MIT)
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

// Rob comes from here: http://bloglitb.blogspot.com/2011/12/access-to-private-members-safer.html
template<typename Tag, typename Tag::Type M>
struct Rob
{
	friend typename Tag::Type Access(Tag)
	{
		return M;
	}
};

#define ROB_DEFINE_VAR(_Class, _VarName, _VarType) \
	struct F##_Class##_VarName##Tag \
	{ \
		using Type = _VarType _Class::*; \
		friend Type Access(F##_Class##_VarName##Tag); \
	}; \
	template struct Rob<F##_Class##_VarName##Tag, &_Class::_VarName>

#define ROB_DEFINE_FUN(_Class, _FunName, _RetType, ...) \
	struct F##_Class##_FunName##Tag \
	{ \
		using Type = _RetType (_Class::*)(__VA_ARGS__); \
		friend Type Access(F##_Class##_FunName##Tag); \
	}; \
	template struct Rob<F##_Class##_FunName##Tag, &_Class::_FunName>

#define ROB_DEFINE_FUN_CONST(_Class, _FunName, _RetType, ...) \
	struct F##_Class##_FunName##Tag \
	{ \
		using Type = _RetType (_Class::*)(__VA_ARGS__) const; \
		friend Type Access(F##_Class##_FunName##Tag); \
	}; \
	template struct Rob<F##_Class##_FunName##Tag, &_Class::_FunName>

#define RobAccess(_Class, _VarName) Access(F##_Class##_VarName##Tag())

Usage example:

class Example
{
	float Var = 0.0f;
	float Fun(float Arg) { return Arg; }
};

ROB_DEFINE_VAR(Example, Var, float);
ROB_DEFINE_FUN(Example, Fun, float, float);

void Usage()
{
	Example Ex;
	Ex.*RobAccess(Example, Var) = 1.0f;
	(Ex.*RobAccess(Example, Fun))(1.0f);
}