Python 4.0 delayed annotation evaluation (from __future__ import annotations ) #63713

New Issue

Arnaud Couturier · 2019-04-18T23:09:57+02:00

Arnaud Couturier commented

2019-04-18 23:09:57 +02:00

Short description of error
Adding
from __future__ import annotations
at the top of a python file makes the properties annotations of operators non-existent.

This will be enabled by default in Python 4.0, see: https://www.python.org/dev/peps/pep-0563

Exact steps for others to reproduce the error
Create and enable this simple demo addon:

from __future__ import annotations # this line makes the line 30 throw an error, because the property some_prop of BUGANNOTATIONS_OT_some_op will no longer exist

bl_info = {
	'name': 'Bug annotations with __future__',
	'author': 'Arnold, Arnaud Couturier, piiichan (couturier.arnaud@gmail.com)',
	'version': (1, 0, 0),
	'blender': (2, 80, 0),
	'location': 'scene options',
	'category': 'Scene',
}

import bpy


class BUGANNOTATIONS_OT_some_op(bpy.types.Operator):
	bl_idname = 'scene.hey'
	bl_label = 'An operator'
	some_prop: bpy.props.StringProperty(name='Hello', default='Default value')


class BUGANNOTATIONS_PT_some_panel(bpy.types.Panel):
	bl_region_type = 'WINDOW'
	bl_space_type = 'PROPERTIES'
	bl_context = 'scene'
	bl_options = {'DEFAULT_CLOSED'}
	bl_label = 'Bug annotations'

	def draw(self, context):
		op = self.layout.operator(BUGANNOTATIONS_OT_some_op.bl_idname)
		print(op.some_prop)


def register():
	bpy.utils.register_class(BUGANNOTATIONS_OT_some_op)
	bpy.utils.register_class(BUGANNOTATIONS_PT_some_panel)


def unregister():
	bpy.utils.unregister_class(BUGANNOTATIONS_PT_some_panel)
	bpy.utils.unregister_class(BUGANNOTATIONS_OT_some_op)

then go in the scene settings, a new panel appears. Show the button inside, and look into the console, you'll see that some_prop from the operator doesn't exist if future is imported.

**Short description of error** Adding `from __future__ import annotations` at the top of a python file makes the properties annotations of operators non-existent. This will be enabled by default in Python 4.0, see: https://www.python.org/dev/peps/pep-0563 **Exact steps for others to reproduce the error** Create and enable this simple demo addon: ``` from __future__ import annotations # this line makes the line 30 throw an error, because the property some_prop of BUGANNOTATIONS_OT_some_op will no longer exist bl_info = { 'name': 'Bug annotations with __future__', 'author': 'Arnold, Arnaud Couturier, piiichan (couturier.arnaud@gmail.com)', 'version': (1, 0, 0), 'blender': (2, 80, 0), 'location': 'scene options', 'category': 'Scene', } import bpy class BUGANNOTATIONS_OT_some_op(bpy.types.Operator): bl_idname = 'scene.hey' bl_label = 'An operator' some_prop: bpy.props.StringProperty(name='Hello', default='Default value') class BUGANNOTATIONS_PT_some_panel(bpy.types.Panel): bl_region_type = 'WINDOW' bl_space_type = 'PROPERTIES' bl_context = 'scene' bl_options = {'DEFAULT_CLOSED'} bl_label = 'Bug annotations' def draw(self, context): op = self.layout.operator(BUGANNOTATIONS_OT_some_op.bl_idname) print(op.some_prop) def register(): bpy.utils.register_class(BUGANNOTATIONS_OT_some_op) bpy.utils.register_class(BUGANNOTATIONS_PT_some_panel) def unregister(): bpy.utils.unregister_class(BUGANNOTATIONS_PT_some_panel) bpy.utils.unregister_class(BUGANNOTATIONS_OT_some_op) ``` then go in the scene settings, a new panel appears. Show the button inside, and look into the console, you'll see that some_prop from the operator doesn't exist if __future__ is imported.

Arnaud Couturier commented

2019-04-18 23:09:57 +02:00

Added subscriber: @piiichan

Sebastian Parborg commented

2019-04-19 13:57:24 +02:00

Added subscribers: @ideasman42, @ZedDB

Sebastian Parborg commented

2019-04-19 13:57:24 +02:00

@ideasman42 do we support this?

Campbell Barton changed title from ~~from __future__ import annotations breaks operators properties annotations~~ to Support for Python 4.0 delayed annotation evaluation (from __future__ import annotations)

2019-04-19 14:27:47 +02:00

Campbell Barton changed title from ~~Support for Python 4.0 delayed annotation evaluation (from __future__ import annotations)~~ to Python 4.0 delayed annotation evaluation (from __future__ import annotations)

2019-04-19 14:28:27 +02:00

Campbell Barton commented

2019-04-19 14:29:35 +02:00

Marking as TODO since it's not used unless you explicitly enable it and it's marked for inclusion in Python 4.0. - Added to #63733

Campbell Barton changed title from ~~Python 4.0 delayed annotation evaluation (from __future__ import annotations)~~ to Python 4.0 delayed annotation evaluation (from __future__ import annotations )

2019-04-19 14:33:21 +02:00

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Python 4.0 delayed annotation evaluation (from __future__ import annotations ) #63713

Python 4.0 delayed annotation evaluation (from future import annotations ) #63713