What does gdscript keyword "is" correspond to in GDNative c++?

UnknownUser

I want to use GDNative c++ to process the InputEvent. For gdscript, we would write:

func _unhandled_input(event):
    if event is InputEventKey:
        if event.pressed and event.scancode == KEY_ESCAPE:
            get_tree().quit()

However, when I write the above code in c++, I don't know how to express the "is" keyword. Can anyone help me? Thanks a lot!

TwistedTwigleg

Welcome to the forums @"Bohang Zhang"!

You probably need to use casting, and then check if you get a null pointer or not, based on my C++ experience with Godot source code. Something like this should work, I think:

InputEventKey *potential_key = Object::cast_to<InputEventKey>(InputEventVariableHere);
if (potential_key):
	// You have a InputEventKey! Do stuff here.

Though it looks like the syntax for GDNative is slightly different than in Godot source, based on this GitHub issue.

So, to adapt the above code to GDNative, you'd need something like this:

godot::InputEventKey *potential_key = godot::Object::cast_to<godot::InputEventKey>(InputEventVariableHere);
if (potential_key):
	// You have a InputEventKey! Do stuff here.

UnknownUser

Thank you @TwistedTwigleg ! However, I see in the header file of the godot_cpp that the unhandled_input is declared as follows: void _unhandled_input(const Ref<InputEvent> event); Here the parameter is a Ref template class. Does the above code need some modifications? Thank you!

TwistedTwigleg

I think you can still cast references, though I'm not 100% positive. I'd try it and see if it works, as worse case it will just crash or error out when compiling.