Dynamic PropertyGroup classes no longer possible in 2.93 #86719

New Issue

Brian Savery (AMD) · 2021-03-18T22:07:03+01:00

2021-03-18 22:07:03 +01:00

System Information
Operating system: *
Graphics card: *

Blender Version
Broken: Blender 2.93 (after https://developer.blender.org/rBc44c611c6d8c6ae071b48efb5fc07168f18cd17e)
Worked: (newest version of Blender that worked as expected)

Short description of error
This is somewhat rare, but IMO perfectly valid Python use case of dynamically creating a new class and then wanting to register it. That is, we want to dynamically subtype a PropertyGroup class, add some properties to it, and then register the class

One example of "why", is for example MaterialX gives us a whole bunch of shader node types specified in xml files that we would like to create custom node types from, so we write a small script to parse the XML and create node classes on the fly.

Exact steps for others to reproduce the error

import bpy

data = {
             'bl_label': "MyNewType",
             'bl_idname': "test.MyNewType",
             '__annotations__': {
                "MyIntVal": (bpy.props.IntProperty, {'name': "MyIntVal", 'default': 42})
             }
         }

my_new_type = type("MyNewType", (bpy.types.PropertyGroup,), data)

bpy.utils.register_class(my_new_type)

bpy.types.Object.my_prop_grp = bpy.props.PointerProperty(type=my_new_type)
print(bpy.data.objects[0].my_prop_grp.MyIntVal)

also attached a blend file with the above script. In 2.93 does not seem like it registers the int property.example.blend. I'm tagging @ideasman42 in this because it seems related to the DeferredProperty when we inspect deeper. If there is another way to achieve creating the properties for these dynamic types let me know.

**System Information** Operating system: * Graphics card: * **Blender Version** Broken: Blender 2.93 (after https://developer.blender.org/rBc44c611c6d8c6ae071b48efb5fc07168f18cd17e) Worked: (newest version of Blender that worked as expected) **Short description of error** This is somewhat rare, but IMO perfectly valid Python use case of dynamically creating a new class and then wanting to register it. That is, we want to dynamically subtype a PropertyGroup class, add some properties to it, and then register the class One example of "why", is for example MaterialX gives us a whole bunch of shader node types specified in xml files that we would like to create custom node types from, so we write a small script to parse the XML and create node classes on the fly. **Exact steps for others to reproduce the error** ``` import bpy data = { 'bl_label': "MyNewType", 'bl_idname': "test.MyNewType", '__annotations__': { "MyIntVal": (bpy.props.IntProperty, {'name': "MyIntVal", 'default': 42}) } } my_new_type = type("MyNewType", (bpy.types.PropertyGroup,), data) bpy.utils.register_class(my_new_type) bpy.types.Object.my_prop_grp = bpy.props.PointerProperty(type=my_new_type) print(bpy.data.objects[0].my_prop_grp.MyIntVal) ``` also attached a blend file with the above script. In 2.93 does not seem like it registers the int property.[example.blend](https://archive.blender.org/developer/F9898605/example.blend). I'm tagging @ideasman42 in this because it seems related to the DeferredProperty when we inspect deeper. If there is another way to achieve creating the properties for these dynamic types let me know.

Brian Savery (AMD) commented

2021-03-18 22:07:03 +01:00

Added subscribers: @ideasman42, @BrianSavery

Bogdan Nagirniak commented

2021-03-19 09:25:52 +01:00

Added subscriber: @bnagirniak

Philippe Crassous commented

2021-03-25 17:20:06 +01:00

Added subscriber: @PhilippeCrassous

AquaticNightmare commented

2021-03-31 19:17:57 +02:00

Added subscriber: @AquaticNightmare

Karlis Upitis commented

2021-04-06 16:26:49 +02:00

Added subscriber: @karlisup

Joshua Knauber commented

2021-04-07 11:30:58 +02:00

Added subscriber: @JoshuaKnauber

Ray Mairlot commented

2021-04-07 11:33:32 +02:00

Added subscriber: @RayMairlot

Philipp Oeser commented

2021-04-07 12:38:54 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-04-07 12:38:54 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Philipp Oeser commented

2021-04-07 12:38:54 +02:00

Looks like a valid usecase, but not sure how to classify.
Will confirm for now though and even dare setting this to High priority -- since I would not be aware of a way around this "new limitation/regression" for now.

Looks like a valid usecase, but not sure how to classify. Will confirm for now though and even dare setting this to High priority -- since I would not be aware of a way around this "new limitation/regression" for now.

Campbell Barton commented

2021-04-07 15:03:04 +02:00

Changed status from 'Confirmed' to: 'Archived'

Campbell Barton closed this issue

2021-04-07 15:03:04 +02:00

Campbell Barton commented

2021-04-07 15:03:04 +02:00

Creating classes dynamically is still supported. The example given relied on an internal representation of properties which was never documented or intended for script authors to depend on.

This works as expected:

import bpy

data = {
    'bl_label': "MyNewType",
    'bl_idname': "test.MyNewType",
    '__annotations__': {
        "MyIntVal": bpy.props.IntProperty(name="MyIntVal",default=42),
    }
}

my_new_type = type("MyNewType", (bpy.types.PropertyGroup,), data)

bpy.utils.register_class(my_new_type)

bpy.types.Object.my_prop_grp = bpy.props.PointerProperty(type=my_new_type)
print(bpy.data.objects[0].my_prop_grp.MyIntVal)

Creating classes dynamically is still supported. The example given relied on an internal representation of properties which was never documented or intended for script authors to depend on. This works as expected: ``` import bpy data = { 'bl_label': "MyNewType", 'bl_idname': "test.MyNewType", '__annotations__': { "MyIntVal": bpy.props.IntProperty(name="MyIntVal",default=42), } } my_new_type = type("MyNewType", (bpy.types.PropertyGroup,), data) bpy.utils.register_class(my_new_type) bpy.types.Object.my_prop_grp = bpy.props.PointerProperty(type=my_new_type) print(bpy.data.objects[0].my_prop_grp.MyIntVal) ```

Philipp Oeser commented

2021-04-07 18:07:20 +02:00

Ah, good to know, thx @ideasman42

Bogdan Nagirniak commented

2021-04-08 10:43:23 +02:00

This example is working, thanks!

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Dynamic PropertyGroup classes no longer possible in 2.93 #86719