Calling derived class function from base class
c++, inheritance, virtual
Solution
The code you've posted should work the way you want. Calling `doSomething` on an instance of `derived` will call the overridden `start` and `stop` functions defined in `derived`.
There's an exception to that, though. If you call `doSomething` in the constructor or destructor of `base` (whether directly or indirectly), then the versions of `start` and `stop` that get called will be the ones defined in `base`. That's because in those circumstances, you don't actually have a valid `derived` instance yet. It's either not fully constructed or partially destructed, so the language prevents you from calling methods that would use the partial object.
If you're not calling it from a `base` constructor or destructor, then there is more to the problem than what's shown here.
Problem
``` class base { public: virtual void start(); virtual void stop(); void doSomething() { start(); .... stop(); } } class derived : public base { public: void start(); void stop(); } ``` But when I call `doSomething()` in the derived class it is using it's own definition of `Start()` and `Stop()` - not the derived ones. I don't want to rewrite `doSomething()` in the derived class because it would be identical to the base one. What am I doing wrong? Sorry if that wasn't clear. The behaviour of Start() and Stop() in the derived class is different (it's a different machine) - but I want to use the original base class doSomething() because that hasn't changed. It just has to start() and stop() using the new derived class code.