Fix to ensure Component::onEnter() is called

[rh101]

Describe your changes

If a component is added to a parent node after the parent Node::onEnter() has been called, then the Component::onEnter() would never be called.

This fix ensures that if the component is added while the parent node is already running, then the Component::onEnter() is called.

Issue ticket number and link

#866

Checklist before requesting a review

• I have performed a self-review of my code
• If it is a core feature, I have added thorough tests.

[DelinWorks]

maybe remove the Component::onEnter from Node::onEnter since your're calling Component::onEnter anyways when it gets added, that's to guarantee that Component::onEnter doesn't get called twice and bring frustrating bugs

for reference:

void Node::onEnter() {
    if (_componentContainer && !_componentContainer->isEmpty()) {
        _componentContainer->onEnter();
    }
}

portion should be removed.

[rh101]

maybe remove the Component::onEnter from Node::onEnter since your're calling Component::onEnter anyways when it gets added

That code should not be removed, since it is still required. Review the code carefully and you will see why.

The Node::_running flag is false until the end of the Node's onEnter() method, so if a component is added prior to Node::onEnter() being called, the only place Component::onEnter() will be called is in Node::onEnter().

Also, if the Node::onExit() is called, which in turn calls Component::onExit(), and then Node::onEnter() is called later, then the components would still need Component::onEnter() to be called. Node::onEnter() is the only place this can occur.

That's why the code is correct and should not be removed at all.

[DelinWorks]

I see..

[aismann]

Maybe a test (cpp-test) with different scenarios will be usefull too?

[rh101]

Maybe a test (cpp-test) with different scenarios will be usefull too?

I don't see any way to test this, as the side effect of the original code is that onEnter() is never called, which would cause undesired behaviour in a component. This fix simply ensures that Component::onEnter() is called regardless of when the component is added to the parent.

The sub-classes that inherit from Component and override Component::onEnter() are Physics3DComponent, NavMeshObstacle and NavMeshAgent, all of which would be buggy if they weren't added to the parent node prior to the parent running Node::onEnter(). The current test cases cover them all, and the changes here have no impact on their operation.