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Calling a const function from a non-const object

Asked 2009-01-02T15:28:50.083
24

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.

c++ function constants
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2 Answers

4

If getProcess() and getProcess() const are not returning a reference to the same object (but differently qualified) then it would indicate a poor design of class Bar. Overloading on the constness of the function is not a good way to distinguish functions with different behaviours.

If they are returning a reference to the same object then:

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

and

getProcess().doSomeWork();

call exactly the same doSomeWork() function so there is no need to use the const_cast.

answered 2009-01-02T15:42:59.197
0

Well, can you declare

void doOtherWork const ()

?

That would do it.

answered 2009-01-02T15:32:49.857

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