How to name this key-oriented access-protection pattern?

Question

Apparently this key-oriented access-protection pattern:

class SomeKey { 
    friend class Foo;
    SomeKey() {} 
    // possibly non-copyable too
};

class B         


        

Answer 1

I like, in decreasing preference:

• passkey friend idiom
• passkey-door friend idiom
• pass-door friend idiom
• key-door friend idiom
• partial-friend idiom
• restricted-friend idiom

_{I moved away from the key-lock/key-keyhole naming scheme to the pass naming scheme, which grew on me.}