Node.replace_by() has strange behavior with instanced scenes

[Jeto143]

Godot version:

3.1

Issue description:

Using Node.replace_by to replace an instanced scene with another one created from script appears to merge the two subscenes instead of actually replacing.

Steps to reproduce:

• Create three scenes: main, other, yetanother, each with a simple Node2D as base node. Then add different sprites to other and yetanother to distinguish between them.
• In the main scene, instantiate the other scene (say, as Other) as a child with the editor.
• Using script attached to main scene's base node, instantiate a yetanother scene with load('res://yetanother.scn') and call .instance() on it (call the resulting variable yetanother).
• Add $Other.replace_by(yetanother) to the following line.

Instead of replacing the initially instanced scene node with the new one, this results in merging the two scenes together (which can be confirmed by looking at the Remote tab's scene tree during execution).

As an additional note, print($Other) will print [Object:null] then (because the node also took the new node's name), which imho is a bit counter-intuitive, though this is easily fixable with yetanother.name = 'Other'. I believe the replaced node should take the initial node's name by default, but that may be intended for reasons I'm missing.

Minimal reproduction project:

replace_by_bug.zip

[bojidar-bg]

Node.replace_by is used by the editor when changing the type of a node in the scene dock. As such, it makes little sense to lose children nodes.

The part of it which you want is just:

var parent = get_parent()
var pos_in_parent = get_position_in_parent()
parent.remove_child(self)
parent.add_child(other)
parent.move_child(other, pos_in_parent)

That being said, the documentation is quite lacking. Retagging.

[Jeto143]

Yes, that's what I've been doing, and it's working fine, I was just curious why that method wouldn't do the same, considering what I thought it should do.

So I was wrong about that--still, replace_by seems a bit misleading as a term to describe a method that doesn't, technically, seem to replace the node it's called on with another :)

(In any case, documentation could at least make that more obvious indeed!)

[starry-abyss]

If it's used by editor and works weirdly for games, maybe it should be made hidden/private from the user?

[berarma]

If it's used by editor and works weirdly for games, maybe it should be made hidden/private from the user?

Improving the documentation should be enough. If it's useful in the editor it can be useful in games and tools running in the editor.