State of Observers — 28 February 2010
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EntitiesObserver works well if you don't erase any entity inside the observer.
Otherwise, it makes Sketchup crash in an ugly way.I'm not sure about EntityObserver but i think that's pretty much the same behavior.
Thank you for the report
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@malkomitch said:
EntitiesObserver works well if you don't erase any entity inside the observer.
Otherwise, it makes Sketchup crash in an ugly way.I'm not sure about EntityObserver but i think that's pretty much the same behavior.
Thank you for the report
In my experience I found adding the observers to cause a delayed crash no matter what - even if I never modified the model. Just attaching it.
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Do you call the same observer several times?
for example, if an AppObserver.onNewModel of your own call a new EntityObserver each time you perform a File>New, you'll stack the EntityObservers without removing the old one. Every methods trigger n times and it may cause unwanted issues.
try to track your observers by storing them in a global variable, for example. And if you find some duplicates, use Sketchup.active_model.entities.remove_observer before calling a new one
In my scripts, if i use observers, i'm used to call a little function "refreshObservers" of my own, triggered by AppObserver.onNewModel or AppObserver.onOpenModel, that flushes all the old observers and create new ones.
I'm using an EntitiesObserver every day. This observer is designed to build and update a catalogue of everything drawn in or removed from sketchup. With onElementAdded and onElementRemoved, I never experienced any crash, excepted when I try to remove an entity inside the EntitiesObserver methods. It breaks the elementary rule: don't touch the collection you're watching in
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hmm... will have to look deeper into it again. but I mean to remember that even when I removed the observers I still got crashes... hm..
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@malkomitch said:
try to track your observers by storing them in a global variable, for example. And if you find some duplicates, use Sketchup.active_model.entities.remove_observer before calling a new one
Very good advice. Also remove_observer will accept without error an observer that is currently not attached - I always use the cliche of "remove followed by add" to ensure you have just 1 observer.
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I just noticed the AppObserver onNewModel event fires even if you hit the Cancel button on the "Save changes" dialog.
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Maybe the most efficient is to use a uniqueclass instance for ALL observers.
The observer class does not even need to be typed (i.e. a subclass of the Sketchup observer classes), as there is no check done by the methodsadd_observer
(like for the Tool classes).All callback methods have different names and the relevant information is always in the arguments, so that you have the context of the entities and objects you 'observe'.
This unique instance can easily be maintained at module level.
Fredo
PS: it is a little bit misleading that the API documentation always shows examples with creationof new observer class everytime it is attached to an entity, like
Sketchup.active_model.entities.add_observer(MyEntitiesObserver.new)
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@unknownuser said:
PS: it is a little bit misleading that the API documentation always shows examples with creation of new observer class everytime it is attached to an entity, like Sketchup.active_model.entities.add_observer(MyEntitiesObserver.new)
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I don't know if this is "right" or not, but here is my approach.
I created a global $jf_observers = {}
Then, create a single instance of the observers I need:$jf_observers[;layers] = JF;;LayersObserver.new
When I need an observer, I register a block of code:
$jf_observers[;layers].register(;onLayerAdded) { |layers, layer| do_something(layer) }
At this point, the observer is attached if it isn't attached (an AppObserver is also created and attached because it needs to re-attach any other observers onNewModel and onOpenModel.)
But, there is only a single instance of each observer in existence. There are a handful of entity-specific observers that do not fall under the AppObserver control. But all of the model-level observers can.
Using this method, any developer can use an observer simply by registering a block of code to be executed on an event.
.register
returns an id so you can later.unregister(id)
the event, too. The observers detach themselves when there are no more events in their queues. I don't really ever see a reason to detach the AppObserver - it can stay attach forever.I am in the process of coding a "suit" of observers that behave in a similar fashion, but I am not really far enough to know if it is a viable or stable strategy; although I think it is a solid approach.
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For my part, I created the SmustardAppObserver that allows plugins to add calls to the Observer instance. When an event is triggered, the observer will parse the list of calls.
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Updated to reflect finding of bugged events in
SelectionObserver
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There also seems to be some oddness with
DefinitionsObserver
. Event's unexpectedly triggering. At least in SU7.1.SU6:
- Group/Component Creation:
onComponentPropertiesChanged
- Paste:
onComponentPropertiesChanged
SU7:
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Group/Component Creation:
onComponentPropertiesChanged
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Paste:
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Before you place the component:
onComponentRemoved
andonComponentPropertiesChanged
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After:
onComponentRemoved
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Ctrl+Move:
onComponentRemoved
Not sure if the
onComponentRemoved
started triggering in SU7.0 or 7.1. - Group/Component Creation:
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InstanceObserver.onClose
does not trigger - at least not under SU7.1. -
EntityObserver - (and possibly others)
it seems that OnEraseEntity is activated after onChangeEntity, which means that if the entity is erased, it can cause bugs for whatever you are trying to do with OnChangeEntity. If OnEraseEntity were activated first, you could create a simple boolean value:
def initialize
@still_here = true
enddef OnEraseEntity(entity)
whatever you want to do...
@still_here = false
enddef OnChangeEntity(entity)
if (still_here)whatever you want to do...
end
endThis is a problem because the entity seems to be erased before OnChangeEntity is called, which means that doing something to the entity gives errors, but your observer doesn't know it until it gets through OnChangeEntity to OnEraseEntity.
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Karen -
@kwalkerman said:
This is a problem because the entity seems to be erased before OnChangeEntity is called, which means that doing something to the entity gives errors, but your observer doesn't know it until it gets through OnChangeEntity to OnEraseEntity.
Yea - the Entity and Entities observers aren't easy to deal with.
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Hi guys,
seems like we have found new observer problem (MacOSX + SketchUp8). When InstanceObserver is attached to the Group and SketchUp is then exited, bugsplat window appears. If the model is saved before exiting SketchUp, no bugsplat window appears.
class TestObserver < Sketchup;;InstanceObserver def onOpen(entity) p 'on called' end def onClose(entity) p 'onClose called' end end # Select a Skethcup Group and call this method # so the observer will be attached to the Group def attach_observer group = Sketchup.active_model.selection[0] group.add_observer(TestObserver.new) end
Can anyone please confirm that?
It seems to be MAC OS X + SketchUp 8 specific problem, Windows version works OK, and SU 7 on Mac OS X too.
Cheers,
N78 -
I've not gotten around to test the InstanceObserver - but I'll see if I can test it this weekend.
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Yes, I can confirm its a repeatable bug on Mac OSX SketchUp 8.
I've logged a very grumpy bug report with Google.
Useful to know you can stop the crash by saving before exiting, but I am disappointed a bug like this could be missed. I know software has bugs in it etc, but this seems like any basic regression testing / smoke testing would flush this one out.
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Does the View.remove_observer method work in SU7.1?
I have a tool that needs to turn a ViewObserver on and off.
In tool methods that receive a view argument:
I use "@observer = view.add_observer(MyViewObserver.new)" to turn it on;
and "view.remove_observer(@observer)" to turn it off.view.remove_observer returns false, and the observer is not removed.
I tried changing @observer to a class variable (@@observer), and it still did not work.
Any ideas?
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hm... I have not tried to remove observers from
view
objects...btw - I am compiling a new observer list: http://forums.sketchucation.com/viewtopic.php?f=180&t=30793
If you find new information not included in the list - can you please let me know so I can update the list?
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