Added Node name to print() of all Nodes by making to_string() in Object virtual, so it can be overriden in C++.

[EricEzaM]

Closes godotengine/godot-proposals#693

func _ready():
	var special_node = $MySpecialNode
	print(special_node)
	
	var node = Node2D.new()
	print(node)
	
	var node2: Node2D = null
	print(node2)

Outputs

MySpecialNode [Node2D:23370662652]
[Node2D:23454548333]
Null

I did not add position to Node2D/3D/Control as I wasn't sure if it was really need. Some people won't need it, and there is the question of whether to return local/global position (or other info).

[ThakeeNathees]

IMO all string log about the object must be inside the brackets
something like : [Node2D(MySpecialNode):23370662652]

[EricEzaM]

I like that idea. I'll make the change when I get up in about 9 hours 😁

[mhilbrunner]

All languages that I know of that have this feature let the programmer completely override the output. I.e. if I only want it to print MySpecialNode, that works. If I still want it to print Node type/name/ID I can do that too by simply adding them to the string manually (as long as I have access to that data of course).

If we do this, we should IMO allow that freedom, and not do this halfway and constrain the output.

Java works that way, C# works that way etc.

Forcing the overriden output to be surrounded by the current output makes this unnecessarily less flexible and useful, IMO.

[akien-mga]

@mhilbrunner That's how it works already AFAIK. If you have a script instance, it will return the result from its to_string() method, which should be implemented in all script instances to allow users to fully specify the return value.

See GDScriptInstance::to_string in modules/gdscript/gdscript.cpp for GDScript.

[mhilbrunner]

Yes, I was talking about the other comments :) but maybe I misunderstood them.

[akien-mga]

Well the discussion is about what the default representation of a Node should be:
https://github.com/godotengine/godot/pull/38819/files#diff-685aaf5e6e44dbc6a5700ebaae623e60R1960

NodeName [Node:ID] vs [Node(NodeName):ID].

[mhilbrunner]

Then I indeed misunderstood. :) I don't personally care much, both are fine as default for me.

[EricEzaM]

Hmm on second thought this morning, I think I will leave it at NodeName [Node:ID] unless changes are requested from core maintainers. I think NodeName [Node:ID], it is quicker to find the information you are looking for, whereas in [Node(NodeName):ID], all the information is condensed and I feel that your eyes have to do more work to find what you are after.

Additionally, doing it this way would not allow me to just use the Object::to_string() base implementation as akien mentioned in his review. Since the info would need to within square the brackets, I would need to construct the whole thing again. Not a big deal I guess, but still.

[Xrayez]

I got surprised that to_string is not virtual in the first place. I'd certainly find this useful for C++ modules development, it's strange that it's possible to do this in GDScript and not in C++, unless I'm missing something. 🤔

I'm currently implementing some data structures in a C++ module which I'd like to expose to scripting, having this feature built-in would solve a lot of hacks.

See goostengine/goost#14 and goostengine/goost#12 to justify this change.

[KoBeWi]

This probably needs rebase after #42093 was merged.

I'm not sure about the string format. When you print a node as a part of longer string separated by spaces, it's less obvious that Name and [Object:ID] are related. Maybe they should be linked with : or -? Or [Name [Object:ID]] 🙃

[EricEzaM]

print(self)
# CoolNode:[SpinBox:28454159399]

[akien-mga]

There's a comment to amend but otherwise it seems good to me.

[KoBeWi]

Is the get_name() ? condition even necessary? I don't think we can have an unnamed node, no?

[akien-mga]

Is the get_name() ? condition even necessary? I don't think we can have an unnamed node, no?

Node must have a name when in the Scene Tree, but outside it they can be unnamed:

var node = Node.new()
print(node.name)
add_child(node)
print(node.name)

Prints:

@@2

[akien-mga]

Thanks!

[akien-mga]

Cherry-picked for 3.4.

[securas]

For the sake of compatibility, this should be made optional. Also, to reduce amount of printed text when necessary.