scene_update_post and scene_update_pre get continuously called #45173

New Issue

Nathan Letwory · 2015-06-24T09:17:22+02:00

Nathan Letwory commented

2015-06-24 09:17:22 +02:00

System Information
Win 10, 2x R9 280x + GT 420

Blender Version
Broken: seems to have been always like this
Worked: -

Short description of error

A handler added to bpy.app.handlers.scene_update_post (or _pre) will be continuously called instead of only on scene update.

Exact steps for others to reproduce the error
Execute script:

import bpy


def my_handler(scene):
    print("hi")

bpy.app.handlers.scene_update_post.append(my_handler)

Observer console output. "hi" is being printed while nothing is changing in the scene.

This should not happen, instead this should be triggered only on actual scene change. (selection, edit, add, delete, etc), probably ok to fire also on animation loop

**System Information** Win 10, 2x R9 280x + GT 420 **Blender Version** Broken: seems to have been always like this Worked: - **Short description of error** A handler added to bpy.app.handlers.scene_update_post (or _pre) will be continuously called instead of only on scene update. **Exact steps for others to reproduce the error** Execute script: ``` import bpy def my_handler(scene): print("hi") bpy.app.handlers.scene_update_post.append(my_handler) ``` Observer console output. "hi" is being printed while nothing is changing in the scene. This should not happen, instead this should be triggered only on actual scene change. (selection, edit, add, delete, etc), probably ok to fire also on animation loop

Nathan Letwory commented

2015-06-24 09:17:22 +02:00

Changed status to: 'Open'

Campbell Barton was assigned by Nathan Letwory

2015-06-24 09:17:22 +02:00

Nathan Letwory commented

2015-06-24 09:17:22 +02:00

Added subscriber: @jesterking

Bastien Montagne commented

2015-06-27 16:06:25 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2015-06-27 16:06:25 +02:00

Yeah, looks like it continuously runs, would not expect that.

Ray Mairlot commented

2015-06-27 16:23:35 +02:00

Added subscriber: @RayMairlot

Dealga McArdle commented

2015-06-28 11:09:28 +02:00

Added subscriber: @tetha.z

Brecht Van Lommel commented

2015-07-19 19:26:48 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2015-07-19 19:26:48 +02:00

This is sort of by design. When this was implemented the actual scene update would run continuously too, since there was no quick way to detect if anything needed to be updated before doing it, . If that was possible the meaning of this callback would probably have been different.

But now that it always runs there's scripts taking advantage of that. For example you can do changes to objects in scene_update_pre in order to have them updated next, which would break if the meaning of this callback changed. I wouldn't consider this a bug really, it would be more of a design in my opinion.

This is sort of by design. When this was implemented the actual scene update would run continuously too, since there was no quick way to detect if anything needed to be updated before doing it, . If that was possible the meaning of this callback would probably have been different. But now that it always runs there's scripts taking advantage of that. For example you can do changes to objects in `scene_update_pre` in order to have them updated next, which would break if the meaning of this callback changed. I wouldn't consider this a bug really, it would be more of a design in my opinion.

Julian Eisel commented

2015-08-08 14:17:34 +02:00

Added subscriber: @JulianEisel

Julian Eisel commented

2015-08-08 14:17:34 +02:00

Changed status from 'Open' to: 'Archived'

Julian Eisel closed this issue

2015-08-08 14:17:34 +02:00

Julian Eisel commented

2015-08-08 14:17:34 +02:00

Agree with @brecht, shouldn't be considered as bug if this is broken by design. Added to todo list , closing.

Agree with @brecht, shouldn't be considered as bug if this is broken by design. Added to [todo list ](http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Tools#Other), closing.

Campbell Barton commented

2019-09-03 07:38:05 +02:00

These have now been removed, a timer can be used when continuous updates are needed.

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scene_update_post and scene_update_pre get continuously called #45173