.. _doc_scripting_continued:

Scripting (continued)
=====================
Notifications
-------------

Godot has a low-level notifications system. You don't  are usually not needed for
scripting, as it's too low-level and virtual functions are provided for
most of them. You can learn more about how notifications work under the hood in :ref:`doc_godot_notifications`.

.. tabs::
 .. code-tab:: gdscript GDScript

    func _notification(what):
        match what:
            NOTIFICATION_READY:
                print("This is the same as overriding _ready()...")
            NOTIFICATION_PROCESS:
                print("This is the same as overriding _process()...")

 .. code-tab:: csharp

    public override void _Notification(int what)
    {
        base._Notification(what);

        switch (what)
        {
            case NotificationReady:
                GD.Print("This is the same as overriding _Ready()...");
                break;
            case NotificationProcess:
                var delta = GetProcessDeltaTime();
                GD.Print("This is the same as overriding _Process()...");
                break;
        }
    }

The documentation of each class in the :ref:`Class Reference <toc-class-ref>`
shows the notifications it can receive. However, in most cases GDScript
provides simpler overridable functions.

Overridable functions
---------------------

Such overridable functions, which are described as
follows, can be applied to nodes:

.. tabs::
 .. code-tab:: gdscript GDScript

    func _enter_tree():
        # When the node enters the Scene Tree, it becomes active
        # and  this function is called. Children nodes have not entered
        # the active scene yet. In general, it's better to use _ready()
        # for most cases.
        pass

    func _ready():
        # This function is called after _enter_tree, but it ensures
        # that all children nodes have also entered the Scene Tree,
        # and became active.
        pass

    func _exit_tree():
        # When the node exits the Scene Tree, this function is called.
        # Children nodes have all exited the Scene Tree at this point
        # and all became inactive.
        pass

    func _process(delta):
        # This function is called every frame.
        pass

    func _physics_process(delta):
        # This is called every physics frame.
        pass

 .. code-tab:: csharp

    public override void _EnterTree()
    {
        // When the node enters the Scene Tree, it becomes active
        // and  this function is called. Children nodes have not entered
        // the active scene yet. In general, it's better to use _ready()
        // for most cases.
        base._EnterTree();
    }

    public override void _Ready()
    {
        // This function is called after _enter_tree, but it ensures
        // that all children nodes have also entered the Scene Tree,
        // and became active.
        base._Ready();
    }

    public override void _ExitTree()
    {
        // When the node exits the Scene Tree, this function is called.
        // Children nodes have all exited the Scene Tree at this point
        // and all became inactive.
        base._ExitTree();
    }

    public override void _Process(float delta)
    {
        // This function is called every frame.
        base._Process(delta);
    }

    public override void _PhysicsProcess(float delta)
    {
        // This is called every physics frame.
        base._PhysicsProcess(delta);
    }