litb is teh famous (private access specifier is private no more)

Date	2012-03-30 18:53 +0100
From	Leigh Johnston <leigh@i42.co.uk>
Newsgroups	comp.lang.c++
Subject	litb is teh famous (private access specifier is private no more)
Message-ID	<r_WdnZDF0_abbujSnZ2dnUVZ8j2dnZ2d@giganews.com> (permalink)

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Should the C++ standard be changed to stop litb's cool (and legal) hack 
to bypass private access specifier?  Bypassing private is very bad IMO.

<code>

template<typename Tag, typename Tag::type M>
struct Rob {
   friend typename Tag::type get(Tag) {
     return M;
   }
};

// use
struct A {
   A(int a):a(a) { }
private:
   int a;
};

// tag used to access A::a
struct A_f {
   typedef int A::*type;
   friend type get(A_f);
};

template struct Rob<A_f, &A::a>;

int main() {
   A a(42);
   std::cout << "proof: " << a.*get(A_f()) << std::endl;
}

</code>

<output>
proof: 42
</output>

http://bloglitb.blogspot.co.uk/2011/12/access-to-private-members-safer.html

/Leigh

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litb is teh famous (private access specifier is private no more) Leigh Johnston <leigh@i42.co.uk> - 2012-03-30 18:53 +0100
  Re: litb is teh famous (private access specifier is private no more) Gareth Owen <gwowen@gmail.com> - 2012-03-31 08:37 +0100
  Re: litb is teh famous (private access specifier is private no more) jacob navia <jacob@spamsink.net> - 2012-03-31 10:47 +0200
    Re: litb is teh famous (private access specifier is private no more) gwowen <gwowen@gmail.com> - 2012-04-03 04:14 -0700
  Re: litb is teh famous (private access specifier is private no more) TJorgenson <tjorgenson@infinera.com> - 2012-03-30 21:29 -0700

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