Argument passing utility with unified outside interface available

foo.cpp

/*
A utility choosing version to call and carry extra information to the call
by argument with a unified outside interface. Call global functions foo, bar, foobar with
just one interface f.foo(int, int, void*, int, int), with arguments after void* directly
fed into what the function void* points to. Change bool types in whole code to add other information to pass.

Type conversions inside structure not so tidy yet.

Copyright (c) ksyx 2021. MIT Licensed.
*/

#include <cstdio>
// #define __PRETTY_FUNCTION__ __FUNCTION__ // nonstandard macro fallback
template<typename ...Args>
struct Foo {
	void foo(void* func, Args... args) {
		printf("%s\n",__PRETTY_FUNCTION__);
		((void (*)(Args...))(func))(args...);
	}
	void foo(bool flag1, void* func, Args... args) {
		printf("%s\n",__PRETTY_FUNCTION__);
		if(!flag1) {
			foo((void*)(func), args...);
		} else ((void (*)(bool, Args...))(func))(1, args...);
	}
	void foo(bool flag1, bool flag2, void* func, Args... args) {
		printf("%s\n",__PRETTY_FUNCTION__ );
		if(!flag1) {
			foo(flag2, (void*)(func), args...);
		} else ((void (*)(bool, bool, Args...))(func))(1, 1, args...);
	}
};
void foobar(bool f, bool p, int x, int y) {
	printf("%s\n",__PRETTY_FUNCTION__);
	printf("%d %d %d %d\n", f, p, x, y);
}
void foo(bool p, int x, int y) {
	printf("%s\n",__PRETTY_FUNCTION__);
	printf("%d %d %d\n", p, x, y);
}
void bar(int x, int y) {
	printf("%s\n",__PRETTY_FUNCTION__);
	printf("%d %d\n", x, y);
}
int main() {
	Foo<int, int> f;
	printf("=== DIRECT CALLS ===\n");
	f.foo(1, 1, (void *)(foobar), 2, 3);
	f.foo(1, (void *)(foo), 2, 3);
	f.foo((void *)(bar), 2, 3);
	printf("=== START FROM BBII ===\n");
	f.foo(0, 1, (void *)(foo), 2, 3);
	f.foo(0, 0, (void *)(bar), 2, 3);
	printf("=== START FROM BII ===\n");
	f.foo(0, (void *)(bar), 2, 3);
	return 0;
}

out.out

=== DIRECT CALLS ===
void Foo<Args>::foo(bool, bool, void*, Args ...) [with Args = {int, int}]
void foobar(bool, bool, int, int)
1 1 2 3
void Foo<Args>::foo(bool, void*, Args ...) [with Args = {int, int}]
void foo(bool, int, int)
1 2 3
void Foo<Args>::foo(void*, Args ...) [with Args = {int, int}]
void bar(int, int)
2 3
=== START FROM BBII ===
void Foo<Args>::foo(bool, bool, void*, Args ...) [with Args = {int, int}]
void Foo<Args>::foo(bool, void*, Args ...) [with Args = {int, int}]
void foo(bool, int, int)
1 2 3
void Foo<Args>::foo(bool, bool, void*, Args ...) [with Args = {int, int}]
void Foo<Args>::foo(bool, void*, Args ...) [with Args = {int, int}]
void Foo<Args>::foo(void*, Args ...) [with Args = {int, int}]
void bar(int, int)
2 3
=== START FROM BII ===
void Foo<Args>::foo(bool, void*, Args ...) [with Args = {int, int}]
void Foo<Args>::foo(void*, Args ...) [with Args = {int, int}]
void bar(int, int)
2 3