EntitiesObserver and Attributes - work around

rvs1977 · 31 Jul 2012, 20:28

Next problem:

When deleting a group, and undoing - it looses all the observers.
Well, have to look at that tomorrow.

Luckily it keeps the attributes as far as I can see...

Dan, ok I stay away from win32api for a while

rvs1977 · 1 Aug 2012, 16:38

Think I found a usable solution to this problem:
(It only works in SU8+)

Add EntitiesObserver to each Entity with the attributes("rsdict","area")
Keep the EntitiesObservers when undoing a deleted group
Keep the EntitiesObservers when copying a group.
Add EntitiesOberservers to each group with the attributes ("rsdict", "area")

The solution seems to be simple: - Every time something happens (like undo or change, etc.) the executed observer iterates through each entity and, in my case, when it finds an entity with the attributes ("rsdict", "area") it simply add_observer(MyEntitiesObserver.new).

It can be testet with the two pieces of codes below.
In this example it messures the area of the green face, when you pushpull the red face at the top.

In the first codepiece it draws some boxes and adds some attributes, but dont add any observers. Try to run the code a few times so it will produce a number of boxes.


mod = Sketchup.active_model # Open model
ent = mod.entities # All entities in model
sel = mod.selection # Current selection

pts = []

pts[0] = [ 0, 0, 0]
pts[1] = [ 1000.mm, 0, 0]
pts[2] = [ 1000.mm, 1000.mm, 0]
pts[3] = [ 0, 1000.mm, 0]

pts[4] = [ 0, 0, 1000.mm]
pts[5] = [ 1000.mm, 0, 1000.mm]
pts[6] = [ 1000.mm, 1000.mm, 1000.mm]
pts[7] = [ 0, 1000.mm, 1000.mm]

10.times do |i|
    rsgroup = ent.add_group
    
    rsgroup.entities.add_face pts[0..3]
    yv_face_height = rsgroup.entities.add_face pts[4..7]
    rsgroup.entities.add_face pts[0], pts[3], pts[7], pts[4]
    rsgroup.entities.add_face pts[3], pts[2], pts[6], pts[7]
    yv_face_length = rsgroup.entities.add_face pts[1], pts[2], pts[6], pts[5]
    yv_face_area = rsgroup.entities.add_face pts[0], pts[1], pts[5], pts[4]
    
    yv_face_height.pushpull rand(1000.mm)
    yv_area = yv_face_area.area.to_m.to_m
    yv_face_area.material = (0xAADEAA) #green
    yv_face_height.material =(0x8811FF) #red
    rsgroup.set_attribute "rsdict","area", yv_area
    yv_face_area.set_attribute "rsdict", "yv_face_area", yv_area
    yv_face_length.set_attribute "rsdict", "yv_face_length" , 0
    yv_face_height.set_attribute "rsdict", "yv_face_height", 0
        
    point = Geom;;Point3d.new (1100.mm * i, 0, 0)
    t = Geom;;Transformation.new point
    rsgroup.transform! t
       
    
end #times_do

ent.each do |o|
    point = Geom;;Point3d.new (0, 1100.mm, 0)
    t = Geom;;Transformation.new point
    o.transform! t
end #each_do

Second piece of code: - Here it add the observers. Every time the code is executed it will asign the observers. And it seems like it doesnt matter how many times you do it.There will only be one observer for each entity.


mod = Sketchup.active_model # Open model
ent = mod.entities # All entities in model
sel = mod.selection # Current selection

class MyModelObserver < Sketchup;;ModelObserver
    def onTransactionUndo(model)    
        #UI.messagebox("onTransactionUndo; " + model.to_s)
        Sketchup.active_model.entities.each do |o|
            attr = o.get_attribute "rsdict","area"
    
            if attr  
                o.add_observer(MyEntityObserver.new)    
                o.entities.add_observer(MyEntitiesObserver.new)                
            end
        end        
    end    
end #MyModelObserver
#Adding ModelObserver - Undo
Sketchup.active_model.add_observer(MyModelObserver.new)

class MyEntityObserver < Sketchup;;EntityObserver        
    #def onEraseEntity(entity) #this work        
        #UI.messagebox("onEraseEntity; " + entity.to_s)        
    #end
    
    #def onChangeEntity(entity)    
        #UI.messagebox("onChangeEntity; " + entity.to_s)
    #end
end #class

class MyEntitiesObserver < Sketchup;;EntitiesObserver        
    def onElementModified(entities, entity)    
        attr_length = entity.get_attribute "rsdict", "yv_face_length"
        attr_height = entity.get_attribute "rsdict", "yv_face_height"       
		
		if attr_length           
            entities.each do |i|
                attr_area = i.get_attribute "rsdict", "yv_face_area"
                
                if attr_area
                    yv_area_new = i.area.to_m.to_m
                    #UI.messagebox "Length changed - area before; " + attr_area.to_s + " m² - area after; " + yv_area_new.to_s + " m²"                    
                    i.set_attribute "rsdict", "yv_face_area", yv_area_new
                end #attr_area
            end #each do
        end #if attr_length
        
		
        if attr_height            
            entities.each do |i|
                attr_area = i.get_attribute "rsdict", "yv_face_area"
                
                if attr_area
                    yv_area_new = i.area.to_m.to_m
                    UI.messagebox "Height changed - green face - area before; " + attr_area.to_s + " m² - area after; " + yv_area_new.to_s + " m²"                    
                    i.set_attribute "rsdict", "yv_face_area", yv_area_new
                end #attr_area
            end #each do
        end #if attr_height
        
    end #onElementModified_end   
end #class

i = 0
ent.each do |o|
    attr = o.get_attribute "rsdict","area"
    
    if attr  
        o.add_observer(MyEntityObserver.new)    
        o.entities.add_observer(MyEntitiesObserver.new)
        i += 1
    end
end

UI.messagebox "number of boxes; " + i.to_s

thomthom · 1 Aug 2012, 17:06

There is still the problem that you modify the model on observer events. When you do that you interfer with any operation that is going on - which might be in the middle of a start/commit operation of another plugin or native tool. You'll be adding to the Undo stack - causing unexpected behaviour when the user expects to undo their last operation but instead the undo is your injected attribute change.
Model change at observer events may cause bug splats.

rvs1977 · 1 Aug 2012, 18:54

@thomthom said:

There is still the problem that you modify the model on observer events. When you do that you interfer with any operation that is going on - which might be in the middle of a start/commit operation of another plugin or native tool. You'll be adding to the Undo stack - causing unexpected behaviour when the user expects to undo their last operation but instead the undo is your injected attribute change.
Model change at observer events may cause bug splats.

Im not sure how to do it yet, but I think a solution could be to remove the observers, when editing the group, and adding the observer again when finished.

It seems to be very quick to add observers to ALL the entities in the model, and its not possible to add more than one observer to each entity, so you dont have to take care if the entity allready has got one.

thomthom · 2 Aug 2012, 07:31

@rvs1977 said:

It seems to be very quick to add observers to ALL the entities in the model

Strongly recommend you use observers sparsely. Also what you do within the events. Some events trigger many times a second - and that mean you can easily bog down SketchUp.

@rvs1977 said:

and its not possible to add more than one observer to each entity, so you dont have to take care if the entity allready has got one.

Yes you can add more than one observer.

rvs1977 · 2 Aug 2012, 09:09

@rvs1977 said:

and its not possible to add more than one observer to each entity, so you dont have to take care if the entity allready has got one.

@thomthom said:

Yes you can add more than one observer.

What I meant was, if you do like this:
(adding 3 identical observers to one entity)
Code:
[....]
mygroup.entities.add_observer(myEntitiesObserver.new)
mygroup.entities.add_observer(myEntitiesObserver.new)
mygroup.entities.add_observer(myEntitiesObserver.new)
[....]

it will only have one myEntitesObserver attached to mygroup. - not three. That means its easier to handle... You dont need to check if its allready added, its faster just to add new one to every entities.

Yes you can add more observers to one entity eg. MyEntitiesObserverWatchFaces and MyEntitiesObserverWatchEdges

thomthom · 2 Aug 2012, 09:22

Not correct. For each new instance of your observer class you attach you add an observer:

Here I first drew one line. Then added another observer. When I draw a second line I get two observer triggering - and they are both of the same class.

However, if you attach the same instance of your observer to the same element, then it's no extra observers added:

Here I only ever get one observer triggering - because I'd only ever attached a single instance.

I store the reference to the observers I use. Then I remove it - just to be sure.

` @entities_observer = myEntitiesObserver.new

def self.observers
mygroup.entities.remove_observer( @entities_observer )
mygroup.entities.add_observer( @entities_observer )
end`

Just to be sure

rvs1977 · 2 Aug 2012, 09:53

@thomthom said:

Not correct. For each new instance of your observer class you attach you add an observer

Ok, maybe you are right, but to me it seems like it only triggers once, even though I have attached it many times in a row.

Could it be that it is overwritten each time its attached?! As far as I can see its not possible to see which observers is added in the model.

If you try the code I have attached above you can what I mean...
(Run the first code a couple of times to get some boxes without observers, then run the second code as many times you want, and the observers only triggers once)

thomthom · 2 Aug 2012, 10:48

@rvs1977 said:

Could it be that it is overwritten each time its attached?!

If you attach the same instance. But if you do like in my second example, you keep a reference to an instance and use that reference when you attach observers it won't create duplicates.

@rvs1977 said:

As far as I can see its not possible to see which observers is added in the model.

Correct, there isn't.

thomthom · 2 Aug 2012, 10:57

@rvs1977 said:

If you try the code I have attached above you can what I mean...
(Run the first code a couple of times to get some boxes without observers, then run the second code as many times you want, and the observers only triggers once)

Got a sample model with "Boxes"?
What do you do to trigger the events?

Btw - you know that model.entities isn't all the entities in the model? It's just the root context. The rest of the entities is inside Groups, Components and Image entities.
http://www.thomthom.net/thoughts/2012/02/definitions-and-instances-in-sketchup/

rvs1977 · 2 Aug 2012, 11:18

@thomthom said:

Got a sample model with "Boxes"?
What do you do to trigger the events?

In post number 7 in this thread there are two pieces of codes attached...
The 1. piece of code draw boxes without observers, the 2. piece of code add observers to the boxes.
When you have deleted a box, try to undo, and it attaches new observers in a way that it solves the problem with lost observers.

It triggers when the red face is modified (push/pulled) using the def onElementModified(entities, entity) in the "MyEntitesObserver", and it messure the area of the green face.

thomthom · 2 Aug 2012, 11:40

Ok - seeing it now. Still trying to work out the code flow.

But you still have the issue with setting observers adds to the Undo stack.
So when you push pull - the observer triggers and add an event to the Undo stack. So when the user press undo after push/pull he first undo the attribute change - then he has to undo again to undo the push pull.
If the user undo just one - he will have undone the attribute change, but not the push-pull - making your data invalid. Also, the user is likely to become frustrated that Undo is working unpredictably.

thomthom · 2 Aug 2012, 11:46

Worked out why your observer triggered only once:
The set_attribute call short-circuited the other events. When I commented out set_attribute and also changed the UI::Messagebox to this:
puts "#{self} - Height changed - green face - area before: " + attr_area.to_s + " m² - area after: " + yv_area_new.to_s + " m²"
You will then see that all the MyEntitiesObserver.new adds new observers - and doesn't remove the old ones. You'll see it output events for each instance you created. It was just your model change that prevented the events to propagate.

<span class="syntaxdefault"><br />&nbsp;&nbsp;&nbsp;&nbsp;mod&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">Sketchup</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">active_model&nbsp;</span><span class="syntaxcomment">#&nbsp;Open&nbsp;model<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">ent&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">mod</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">entities&nbsp;</span><span class="syntaxcomment">#&nbsp;All&nbsp;entities&nbsp;in&nbsp;model<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">sel&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">mod</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">selection&nbsp;</span><span class="syntaxcomment">#&nbsp;Current&nbsp;selection<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">class&nbsp;</span><span class="syntaxdefault">MyModelObserver&nbsp;</span><span class="syntaxkeyword"><&nbsp;</span><span class="syntaxdefault">Sketchup</span><span class="syntaxkeyword">;;</span><span class="syntaxdefault">ModelObserver<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;def&nbsp;onTransactionUndo</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">model</span><span class="syntaxkeyword">)&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxcomment">#UI.messagebox("onTransactionUndo;&nbsp;"&nbsp;+&nbsp;model.to_s)<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">Sketchup</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">active_model</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">entities</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">each&nbsp;</span><span class="syntaxkeyword">do&nbsp;|</span><span class="syntaxdefault">o</span><span class="syntaxkeyword">|<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">attr&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">o</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">get_attribute&nbsp;</span><span class="syntaxstring">"rsdict"</span><span class="syntaxkeyword">,</span><span class="syntaxstring">"area"<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">if&nbsp;</span><span class="syntaxdefault">attr&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;o</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">add_observer</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">MyEntityObserver</span><span class="syntaxkeyword">.new)&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">o</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">entities</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">add_observer</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">MyEntitiesObserver</span><span class="syntaxkeyword">.new)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;end&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;end&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;end&nbsp;</span><span class="syntaxcomment">#MyModelObserver<br />&nbsp;&nbsp;&nbsp;&nbsp;#Adding&nbsp;ModelObserver&nbsp;-&nbsp;Undo<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">Sketchup</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">active_model</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">add_observer</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">MyModelObserver</span><span class="syntaxkeyword">.new)<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;class&nbsp;</span><span class="syntaxdefault">MyEntityObserver&nbsp;</span><span class="syntaxkeyword"><&nbsp;</span><span class="syntaxdefault">Sketchup</span><span class="syntaxkeyword">;;</span><span class="syntaxdefault">EntityObserver&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxcomment">#def&nbsp;onEraseEntity(entity)&nbsp;#this&nbsp;work&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;#UI.messagebox("onEraseEntity;&nbsp;"&nbsp;+&nbsp;entity.to_s)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;#end<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;#def&nbsp;onChangeEntity(entity)&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;#UI.messagebox("onChangeEntity;&nbsp;"&nbsp;+&nbsp;entity.to_s)<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;#end<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end&nbsp;</span><span class="syntaxcomment">#class<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">class&nbsp;</span><span class="syntaxdefault">MyEntitiesObserver&nbsp;</span><span class="syntaxkeyword"><&nbsp;</span><span class="syntaxdefault">Sketchup</span><span class="syntaxkeyword">;;</span><span class="syntaxdefault">EntitiesObserver&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;def&nbsp;onElementModified</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">entities</span><span class="syntaxkeyword">,&nbsp;</span><span class="syntaxdefault">entity</span><span class="syntaxkeyword">)&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">attr_length&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">entity</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">get_attribute&nbsp;</span><span class="syntaxstring">"rsdict"</span><span class="syntaxkeyword">,&nbsp;</span><span class="syntaxstring">"yv_face_length"<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">attr_height&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">entity</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">get_attribute&nbsp;</span><span class="syntaxstring">"rsdict"</span><span class="syntaxkeyword">,&nbsp;</span><span class="syntaxstring">"yv_face_height"&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">if&nbsp;</span><span class="syntaxdefault">attr_length&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;entities</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">each&nbsp;</span><span class="syntaxkeyword">do&nbsp;|</span><span class="syntaxdefault">i</span><span class="syntaxkeyword">|<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">attr_area&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">i</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">get_attribute&nbsp;</span><span class="syntaxstring">"rsdict"</span><span class="syntaxkeyword">,&nbsp;</span><span class="syntaxstring">"yv_face_area"<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">if&nbsp;</span><span class="syntaxdefault">attr_area<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;yv_area_new&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">i</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">area</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">to_m</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">to_m<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxcomment">#UI.messagebox&nbsp;"Length&nbsp;changed&nbsp;-&nbsp;area&nbsp;before;&nbsp;"&nbsp;+&nbsp;attr_area.to_s&nbsp;+&nbsp;"&nbsp;m²&nbsp;-&nbsp;area&nbsp;after;&nbsp;"&nbsp;+&nbsp;yv_area_new.to_s&nbsp;+&nbsp;"&nbsp;m²"&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;#i.set_attribute&nbsp;"rsdict",&nbsp;"yv_face_area",&nbsp;yv_area_new<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end&nbsp;</span><span class="syntaxcomment">#attr_area<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end&nbsp;</span><span class="syntaxcomment">#each&nbsp;do<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end&nbsp;</span><span class="syntaxcomment">#if&nbsp;attr_length<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">if&nbsp;</span><span class="syntaxdefault">attr_height&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;entities</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">each&nbsp;</span><span class="syntaxkeyword">do&nbsp;|</span><span class="syntaxdefault">i</span><span class="syntaxkeyword">|<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">attr_area&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">i</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">get_attribute&nbsp;</span><span class="syntaxstring">"rsdict"</span><span class="syntaxkeyword">,&nbsp;</span><span class="syntaxstring">"yv_face_area"<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">if&nbsp;</span><span class="syntaxdefault">attr_area<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;yv_area_new&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">i</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">area</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">to_m</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">to_m<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;puts&nbsp;</span><span class="syntaxstring">"#{self}&nbsp;-&nbsp;Height&nbsp;changed&nbsp;-&nbsp;green&nbsp;face&nbsp;-&nbsp;area&nbsp;before;&nbsp;"&nbsp;</span><span class="syntaxkeyword">+&nbsp;</span><span class="syntaxdefault">attr_area</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">to_s&nbsp;</span><span class="syntaxkeyword">+&nbsp;</span><span class="syntaxstring">"&nbsp;m²&nbsp;-&nbsp;area&nbsp;after;&nbsp;"&nbsp;</span><span class="syntaxkeyword">+&nbsp;</span><span class="syntaxdefault">yv_area_new</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">to_s&nbsp;</span><span class="syntaxkeyword">+&nbsp;</span><span class="syntaxstring">"&nbsp;m²"&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxcomment">#i.set_attribute&nbsp;"rsdict",&nbsp;"yv_face_area",&nbsp;yv_area_new<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end&nbsp;</span><span class="syntaxcomment">#attr_area<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end&nbsp;</span><span class="syntaxcomment">#each&nbsp;do<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end&nbsp;</span><span class="syntaxcomment">#if&nbsp;attr_height<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end&nbsp;</span><span class="syntaxcomment">#onElementModified_end&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end&nbsp;</span><span class="syntaxcomment">#class<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">i&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">0<br />&nbsp;&nbsp;&nbsp;&nbsp;ent</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">each&nbsp;</span><span class="syntaxkeyword">do&nbsp;|</span><span class="syntaxdefault">o</span><span class="syntaxkeyword">|<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">attr&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">o</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">get_attribute&nbsp;</span><span class="syntaxstring">"rsdict"</span><span class="syntaxkeyword">,</span><span class="syntaxstring">"area"<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">if&nbsp;</span><span class="syntaxdefault">attr&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;o</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">add_observer</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">MyEntityObserver</span><span class="syntaxkeyword">.new)&nbsp;&nbsp;&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">o</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">entities</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">add_observer</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">MyEntitiesObserver</span><span class="syntaxkeyword">.new)<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">i&nbsp;</span><span class="syntaxkeyword">+=&nbsp;</span><span class="syntaxdefault">1<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;end<br />&nbsp;&nbsp;&nbsp;&nbsp;end<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;UI</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">messagebox&nbsp;</span><span class="syntaxstring">"number&nbsp;of&nbsp;boxes;&nbsp;"&nbsp;</span><span class="syntaxkeyword">+&nbsp;</span><span class="syntaxdefault">i</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">to_s<br /></span>

rvs1977 · 2 Aug 2012, 12:28

I'm not sure how to do these tests.

Are you saying if I pushpull one red face, it triggers events for every instance?? (If there is 200 boxes it triggers 200 times?) (box=instance)

Or will it trigger the number of times, you have runned the script which adds observers? (instance = observer added)
(Because in my case it only shows the UI.messagebox once)

thomthom · 2 Aug 2012, 12:44

@rvs1977 said:

Or will it trigger the number of times, you have runned the script which adds observers? (instance = observer added)
(Because in my case it only shows the UI.messagebox once)

As describe above - in your case it triggers only once because when you modify the model with set_attribute it blocks all the other observers attached. Comment out the set_attribute code and you'll see all the observers you added will trigger.
And then it's the issue with the Undo stack which I also mentioned.

rvs1977 · 2 Aug 2012, 14:53

Ok. hopefully there is a solution. If I find one I will return...