// The Badge can only be constructed by T.
template <typename T>
class Badge{
private:
friend T;
Badge() {}
};
// RestrictedFunc can only be called with a AllowedCaller Badge.
class AllowedCaller;
void RestrictedFunc(Badge<AllowedCaller>);
// AllowedCaller calls the RestrictedFunc with a Badge constructed using {}.
class AllowedCaller {
public:
void CallSite() {
RestrictedFunc({});
}
};
void RestrictedFunc(Badge<AllowedCaller>) {};
// DisallowedCaller will not be able to construct the Badge with {}.
// class DisallowedCaller {
// public:
// void CallSite() {
// RestrictedFunc({});
// }
// };
int main() {
AllowedCaller caller;
caller.CallSite();
return 0;
}
