subclass ActionInterval in cocos2d-x v3 alpha? Worked in v 2.1.5.

cocos2d-x C++
#1

In Cocos2d-x 2.1.5 I used to subclass CCActionInterval and call a constructor as:

CCWiggle* CCWiggle::create(float duration, float amount)
{
    CCWiggle *pRet = new CCWiggle();
    if (pRet && pRet->initWithDuration(duration, amount))
    {
        pRet->autorelease();
    }
    else
    {
        CC_SAFE_DELETE(pRet);
    }

    return pRet;
}

Now in V3 I get an error: Allocating an object of abstract class type ‘CCWiggle’

Now I think this is because ActionInterval has virtual functions = 0. When I look in ‘CCActionInterval.h’ I see:

//
    // Overrides
    //
    virtual bool isDone(void) const override;
    virtual void step(float dt) override;
    virtual void startWithTarget(Node *target) override;
    virtual ActionInterval* reverse() const override = 0;
    virtual ActionInterval *clone() const override = 0;

What I dont understand is which ones of these I need to override? All of them? I already override ‘startWithTarget’

How do I do this? I thought that adding:

virtual bool isDone(void) const override;
    virtual void step(float dt) override;
    virtual void startWithTarget(Node *target) override;
    virtual ActionInterval* reverse() const override = 0;
    virtual ActionInterval *clone() const override = 0;

to my header and:

bool CCWiggle::isDone(void) {}
void CCWiggle::step(float dt) {}
cocos2d::ActionInterval* CCWiggle::reverse();
cocos2d::ActionInterval* CCWiggle::clone();

to my .cpp would be enough? but I still get some out of line definitions, so I still misunderstand something.

#2

In C11 override keyword specifies that the method of the base class must be overridden in the derived class. So you have to override every method marked with override keyword.
Moreover, even in C03 and before ‘= 0’ in the declaration of the method means that this method is abstract, thus the whole class is abstract. You can’t instantiate an abstract class.