这种面向关键的访问保护模式是已知的习语吗？ [英] Is this key-oriented access-protection pattern a known idiom?

问题描述

Matthieu M. 在这个答案，我曾经看到，但从来没有conciously考虑一个模式：

Matthieu M. brought up a pattern for access-protection in this answer that i'd seen before, but never conciously considered a pattern:

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

class Bar {
public:
    void protectedMethod(SomeKey);
};

这里只有键类别的 friend 可访问 protectedMethod（）：

Here only a friend of the key class has access to protectedMethod():

class Foo {
    void do_stuff(Bar& b) { 
        b.protectedMethod(SomeKey()); // fine, Foo is friend of SomeKey
    }
};

class Baz {
    void do_stuff(Bar& b) {
        b.protectedMethod(SomeKey()); // error, SomeKey::SomeKey() is private
    }
};

它允许更精细的访问控制比 Foo a c> c>，避免更复杂的代理模式。

It allows more fine-granular access-control than making Foo a friend of Bar and avoids more complicated proxying patterns.

有人知道这种方法是否已经有一个名字，即是一个已知的模式？

Does anyone know whether this approach already has a name, i.e., is a known pattern?

推荐答案

要您的其他问题，它看起来像是这种模式

Thanks to your other question it looks like this pattern is now known as the "passkey" pattern.

在C ++ 11中，它更清晰，因为它不是调用

In C++11, it gets even cleaner, because instead of calling

b.protectedMethod(SomeKey());

您可以直接致电：

b.protectedMethod({});

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