Sorry if the title is unclear.
I'm working on an addon which involves a UI with a list of IntProperties. I need to be able to add and remove elements from that list on the fly, and I want the min/max values of these elements to vary. See comments in the code snippet below for further explanation, and feel free to copy/paste this straight into blender to test it for yourself. Just have an armature as your active object, in Blender 2.8, run the script and check the new category created on the N panel.
import bpy my_armature = bpy.context.object my_min = 2 my_max = 7 # So first in order to be able to add and remove properties on the fly at all, # I need to put them in a CollectionProperty, # which I can only do by extending bpy.types.PropertyGroup. # (Correct me if I'm wrong about anything this far) class IntPropContainer(bpy.types.PropertyGroup): # While declaring the property, I pass in the my_min and my_max from outside the class scope. # As of 2.8 I have to use ':' instead of '=' for creating properties, for reasons that are unclear to me. value: bpy.props.IntProperty(name="Int Property", min=my_min, max=my_max) bpy.utils.register_class(IntPropContainer) bpy.types.Armature.my_ints = bpy.props.CollectionProperty(type=IntPropContainer) # Adding a property to the collection my_min = 5 my_max = 10 my_new_int = my_armature.data.my_ints.add() # I would expect my_new_int.value to have its min and max set to 5 and 10. class MyUI(bpy.types.Panel): bl_space_type = 'VIEW_3D' bl_region_type = 'UI' bl_idname = "OBJECT_PT_my_ui" bl_label = "My Label" bl_category = "My Category" def draw(self, context): layout = self.layout layout.row().prop(my_armature.data.my_ints, 'value') # The min/max of the property are the original 2/7 instead of the new 5/10. bpy.utils.register_class(MyUI)
The problem: I expected the value I added to the UI to have its min/max set to 5/10, but instead it's 2/7 - the original values of my_min and my_max. This means any properties I create within this colelction property will have the same min and max values, which is not what I want.
I can of course add my_min and my_max variables to within my IntPropContainer class, and then set an update callback function to clamp the value to within those bounds BUT this is not ideal because it allows the user to move the slider out of the min/max bounds, and only after they let go of left mouse will it snap back, which makes this solution very clunky from the user's POV.
Reason I want to use IntProperty over ID Properties
This is simply because I want to use the update callback of IntProperty, ie. I want to run a function whenever a value is changed. Finding a way to do this for ID Properties could very well be an alternate solution to my specific problem.