c++ - Calling a const function from a non-const object

Question

I need to call a const function from a non-const object. See example

struct IProcess {
   virtual bool doSomeWork() const = 0L;
};
class Foo : public IProcess {    
  virtual bool doSomeWork() const {
    ...
  }
};

class Bar
{
public:
   const IProcess& getProcess() const {return ...;}
   IProcess& getProcess() {return ...;}

   void doOtherWork {
    getProcess().doSomeWork();        
  }
};

Calling

getProcess().doSomeWork();

will always results in a call to

IProcess& getProcess()

Is there another way to call

const IProcess& getProcess() const 

from a non constant member function? I have so far used

const_cast<const Bar*>(this)->getProcess().doSomeWork();

which does the trick but seems overly complicated.

---

Edit: I should mention that code is being refactored and eventually only one function will remain.

const IProcess& getProcess() const 

However, currently there is a side effect and the const call may return a different instance of IProcess some of the time.

Please keep on topic.

Answer 1

const_cast is for casting away constness!

You're casting from non-const to const which is safe, so use static_cast:

   static_cast<const Bar*>(this)->getProcess().doSomeWork();

I mean techincally speaking you can cast in constness with const_cast, but it's not a pragmatic use of the operator. The purpose of new style casts (versus the old c-style cast), is to communicate the intent of the cast. const_cast is a code smell, and it's use should be reviewed at least. static_cast on the other hand is safe. But it's a matter of C++ style.

Or you can create a new (private) const method, and call that from doOtherWork:

  void doSomeWorkOnProcess() const { getProcess().doSomeWork(); }

Using a const temporary is also an option (answer by "MSN"):

   const Bar* _this = this;
   _this->getProcess().doSomeWork();