Question

Disclaimer

Yes, I am fully aware that what I am asking about is totally stupid and that anyone who would wish to try such a thing in production code should be fired and/or shot. I’m mainly looking to see if can be done.

Now that that’s out of the way, is there any way to access private class members in C++ from outside the class? For example, is there any way to do this with pointer offsets?

(Naive and otherwise non-production-ready techniques welcome)

Update

As noted in the comments, I asked this question because I wanted to write a blog post on over-encapsulation (and how it affects TDD). I wanted to see if there was a way to say "using private variables isn’t a 100% reliable way to enforce encapsulation, even in C++." At the end, I decided to focus more on how to solve the problem rather than why it’s a problem, so I didn’t feature some of the stuff brought up here as prominently as I had planned, but I still left a link.

At any rate, if anyone’s interested in how it came out, here it is: Enemies of Test Driven Development part I: encapsulation (I suggest reading it before you decide that I’m crazy).

Answer 1

If the class contains any template member functions you can specialize that member function to suit your needs. Even if the original developer didn’t think of it.

safe.h

class safe {     int money;  public:     safe()      : money(1000000)     {     }      template <typename T>     void backdoor()     {         // Do some stuff.     } }; 

main.cpp:

#include <safe.h> #include <iostream>  class key;  template <> void safe::backdoor<key>() {     // My specialization.     money -= 100000;     std::cout << money << '\n'; }  int main() {     safe s;     s.backdoor<key>();     s.backdoor<key>(); } 

Output:

900000 800000