my goal is to be able to detect when a child object is renamed in a way to display actual name and associated length value in every moment. I first have a list of all name of object children. If an object is renamed, I want to replace the ancient name in my list by the new one. However, it is not working when I rename several children.. Maybe there are others way to do it, or something I don't see in my code ? Thank you.

           for child in obj.children :
                if child.name not in bpy.types.Object.allnameList :
                    # A rename happened : Find the name to replace :
                    for w in range(len(bpy.types.Object.allnameList)):
                        if bpy.types.Object.allnameList[w] != child.name  and (bpy.types.Object.allnameList[w] not in obj.children) :
                            bpy.types.Object.allnameList[w] = child.name

Pointer property

Use a simple collection property with a name and a pointer to an object

import bpy

from bpy.props import CollectionProperty, PointerProperty

class ObjCollection(bpy.types.PropertyGroup):
    object = PointerProperty(type=bpy.types.Object)

def register():    
    bpy.types.Object.foo = CollectionProperty(type=ObjCollection)

if __name__ == "__main__":

I've added the foo collection to every object... now off to the python console to test, clear the objects list

>>> C.object.foo.clear()

Load up every object in scene to context objects "foo" collection

>>> for o in C.scene.objects:
...     item = C.object.foo.add()
...     item.name = o.name
...     item.object = o

Rename every object in scene to "Bar"

>>> for o in C.scene.objects:
...     o.name = "Bar"

Iterate over context object foo

>>> for o in C.object.foo:
...     o.name, o.object.name
('Cube', 'Bar.001')
('Lamp', 'Bar')
('Camera', 'Bar.002')

The object formerly known as "Cube" is now known as "Bar.001" etc.

If the object has been since removed then

C.object.foo["Lamp"].object is None

We know that the lamp, "Bar" formerly named "Lamp" has been removed.

Please note: have defined the properties on classes eg bpy.types.Object and then deal with instances eg context.object. In your question code it appears you have monkey patched a list onto the class bpy.types.Object (the one and only...) instead of, as shown in above, the instances of that type (many)

  • $\begingroup$ Thank you a lot for your answer, it works well in the python console. However, I have no Idea why, but when I want to bring it in my addon, the 'bpy.utils.register_class(ObjCollection)' line creates errors 'type object has no attribute X' which is habitually not there, X is an attribute I also add to bpy.types.Object in my register lines . $\endgroup$ – art2611 Jul 31 '19 at 8:35
  • $\begingroup$ Added minimal register code. The answer gives an example of how to detect name changes using a pointer property. Any attempt to answer why it doesn't register in your addon is a pure guessing game on my part. I will reiterate that monkey-patching a list onto a class, (eg bpy.types.Foo.xxx = []). as displayed in question code, is not (IMO) the way to go. $\endgroup$ – batFINGER Aug 1 '19 at 14:01

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