Write-Only Reference in C++?
- by Robert Mason
Is there a way to code a write-only reference to an object? For example, suppose there was a mutex class:
template <class T> class mutex {
protected:
T _data;
public:
mutex();
void lock(); //locks the mutex
void unlock(); //unlocks the mutex
T& data(); //returns a reference to the data, or throws an exception if lock is unowned
};
Is there a way to guarantee that one couldn't do this:
mutex<type> foo;
T& ref;
foo.lock();
ref = foo.data();
foo.unlock();
//I have a unguarded reference to foo now
On the other hand, is it even worth it? I know that some people assume that programmers won't deliberately clobber the system, but then, why do we have private variables in the first place, eh? It'd be nice to just say it's "Undefined Behavior", but that just seems a little bit too insecure.
