Object property getter infinite loop

Here is my issue : I would like to add a unique Int property on an object.

This property needs to be unique even when duplicated. So according to Duplicating object and default value of property and https://blenderartists.org/forum/showthread.php?328009-Unique-object-id I did this :

# Getter for anchor duplicate
def get_global_index(self):
#    print("getting value")
done = False
# get current index
index = self.global_index #Recursive ?!
# chek if already used (in case of a duplicate) and try a new one while necessary
while not done:
anchors = [obj for obj in bpy.context.scene.objects if obj.type == 'EMPTY' and obj.empty_draw_type == 'PLAIN_AXES']
if any(obj.global_index == self.global_index for obj in anchors):
# found to try another index
print("Trying another index")
index = context.scene.global_index
context.scene.global_index+=1
else:
done = True
print("FOUND index")

return index

def register():
bpy.types.Object.list_index = bpy.props.IntProperty(name = "Index for my_list", default = 0)
#Each anchor needs a unique index
bpy.types.Scene.global_index = bpy.props.IntProperty(name = "Global index for Anchors", default = 0)
#So use scene index to store the increment
bpy.types.Object.global_index = bpy.props.IntProperty(name = "Object index for Anchors", default = 0, get=get_global_index)


BUT, The getter seems to loop infinitely and I don't understand what I'm doing wrong. I just want the getter to check in the current objects of the specified king to check if the index is not already used (when Duplicated) because I need to have each one of them having a unique index.

Thanks !

• In your getter for Object.global_index you have if any(obj.global_index == self.global_index for obj in anchors): Note that obj.global_index uses the getter, hence the infinite recursion. – batFINGER May 15 '17 at 16:19
• I see, thanks. So do you have any suggestion on how to manage this problem ? The only idea I have right now is to reference any index in a separate list, or to increment it on each get (but will increase very quickly ?) – Ange_blond May 16 '17 at 7:58

So, based on this Duplicating object and default value of property I think I found a way.

I use a second identical property to avoid having to get from the getter

Here it is :

# Getter for anchor duplicate
def get_global_index(self):

# get current index
index = self.hidden_index

# chek if already used (in case of a duplicate) and try a new one while necessary
# Do not forget to remove self from result !
anchors = [obj for obj in bpy.context.scene.objects if obj.type == 'EMPTY' and obj.empty_draw_type == 'PLAIN_AXES' and obj != self]

while any(obj.hidden_index == index for obj in anchors):
# found to try another index
index +=1

self.hidden_index = index;
return self.hidden_index

def register():
bpy.types.Object.global_index = bpy.props.IntProperty(name = "Object index for Anchors", default = 0, get=get_global_index)
bpy.types.Object.hidden_index = bpy.props.IntProperty(default = 0, options={'HIDDEN'})


Since it the getter, I just need to return the new value. Using an other property without getter but with the same value, I can get the copied value from the getter.