Help Understanding Classes and Class objects
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Hello all,
I would like to make a class that is a collection of other class objects. I am having a tough time determining exactly how to do this.
st_ep and end_ep end up as class objects but I can't add them to a group in the the class Conveyor draw method. I can't access the objects at all it seems for grouping, transformations etc. Any help where my thought process is wrong would be greatly appreciated. I have been searching all over for an answer.<span class="syntaxdefault"></span><span class="syntaxkeyword">class </span><span class="syntaxdefault">Conveyor<br /> def initialize</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">st_point</span><span class="syntaxkeyword">, </span><span class="syntaxdefault">end_point</span><span class="syntaxkeyword">)<br /> @</span><span class="syntaxdefault">st_point </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">st_point<br /> </span><span class="syntaxkeyword">@</span><span class="syntaxdefault">end_point </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">end_point<br /> end </span><span class="syntaxcomment">#of initialize()<br /><br /> </span><span class="syntaxdefault">def draw</span><span class="syntaxkeyword">()<br /> </span><span class="syntaxdefault">ents </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">Sketchup</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">active_model</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">entities<br /><br /> st_ep </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">EndPulley</span><span class="syntaxkeyword">.new(@</span><span class="syntaxdefault">st_point</span><span class="syntaxkeyword">)<br /> </span><span class="syntaxdefault">st_ep</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">draw<br /> end_ep </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">EndPulley</span><span class="syntaxkeyword">.new(@</span><span class="syntaxdefault">end_point</span><span class="syntaxkeyword">)<br /> </span><span class="syntaxdefault">end_ep</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">draw<br /> <br /> conv_group </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">ents</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">add_group st_ep</span><span class="syntaxkeyword">, </span><span class="syntaxdefault">en_ep<br /> conv_group</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">name </span><span class="syntaxkeyword">= </span><span class="syntaxstring">"CONVEYOR ASSY"<br /> <br /> </span><span class="syntaxdefault">end </span><span class="syntaxcomment">#of draw()<br /><br /></span><span class="syntaxdefault">end </span><span class="syntaxcomment">#of Conveyor class<br /><br /></span><span class="syntaxkeyword">class </span><span class="syntaxdefault">EndPulley<br /><br /> def initialize</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">ins_pt</span><span class="syntaxkeyword">)<br /> @</span><span class="syntaxdefault">ins_pt </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">ins_pt<br /> end </span><span class="syntaxcomment">#of initialize()<br /> <br /> </span><span class="syntaxdefault">def draw</span><span class="syntaxkeyword">()<br /> </span><span class="syntaxdefault">pts </span><span class="syntaxkeyword">= @</span><span class="syntaxdefault">ins_pt<br /> width </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">36<br /> length </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">18<br /> <br /> ents </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">Sketchup</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">active_model</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">entities<br /> pt1 </span><span class="syntaxkeyword">=[</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">0</span><span class="syntaxkeyword">] - (</span><span class="syntaxdefault">width</span><span class="syntaxkeyword">/</span><span class="syntaxdefault">2</span><span class="syntaxkeyword">),</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">1</span><span class="syntaxkeyword">],</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">2</span><span class="syntaxkeyword">]]<br /> </span><span class="syntaxdefault">pt2 </span><span class="syntaxkeyword">=[</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">0</span><span class="syntaxkeyword">] - (</span><span class="syntaxdefault">width</span><span class="syntaxkeyword">/</span><span class="syntaxdefault">2</span><span class="syntaxkeyword">),</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">1</span><span class="syntaxkeyword">]+</span><span class="syntaxdefault">length</span><span class="syntaxkeyword">,</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">2</span><span class="syntaxkeyword">]]<br /> </span><span class="syntaxdefault">pt3 </span><span class="syntaxkeyword">=[</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">0</span><span class="syntaxkeyword">] + (</span><span class="syntaxdefault">width</span><span class="syntaxkeyword">/</span><span class="syntaxdefault">2</span><span class="syntaxkeyword">),</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">1</span><span class="syntaxkeyword">]+</span><span class="syntaxdefault">length</span><span class="syntaxkeyword">,</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">2</span><span class="syntaxkeyword">]]<br /> </span><span class="syntaxdefault">pt4 </span><span class="syntaxkeyword">=[</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">0</span><span class="syntaxkeyword">] + (</span><span class="syntaxdefault">width</span><span class="syntaxkeyword">/</span><span class="syntaxdefault">2</span><span class="syntaxkeyword">),</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">1</span><span class="syntaxkeyword">],</span><span class="syntaxdefault">pts</span><span class="syntaxkeyword">[</span><span class="syntaxdefault">2</span><span class="syntaxkeyword">]]<br /><br /> <br /> </span><span class="syntaxdefault">face </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">ents</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">add_face pt1</span><span class="syntaxkeyword">,</span><span class="syntaxdefault">pt2</span><span class="syntaxkeyword">,</span><span class="syntaxdefault">pt3</span><span class="syntaxkeyword">,</span><span class="syntaxdefault">pt4<br /> group </span><span class="syntaxkeyword">= </span><span class="syntaxdefault">ents</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">add_group face<br /> group</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">name </span><span class="syntaxkeyword">= </span><span class="syntaxstring">"END PULLEY"<br /> </span><span class="syntaxdefault">face</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">reverse</span><span class="syntaxkeyword">!<br /> </span><span class="syntaxdefault">face</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">pushpull 5<br /> end </span><span class="syntaxcomment">#of draw()<br /></span><span class="syntaxdefault">end </span><span class="syntaxcomment">#of EndPulley class </span><span class="syntaxdefault"></span> -
(please wrap code in phpBB code tags, with space indenting.)
Sorry ...
(1) We cannot create custom
Sketchup::Drawingelementsubclasses. (The app would not know how to render them, .. nor how to export them to other file formats.)(2) The
drawmethod is used only for aToolclass to draw temporary geometry, guidelines etc. as the user moves the mouse, before they commit the 2nd point. (Notice how the rectangle tool works. The temporary stretchy rectangle after the first point would be drawn with thedrawmethod.)(3) What you want to do, is create a Group or Component, that is named "Pulley" and "Conveyor". Perhaps even DynamicComponents.
But you dont really need to create Ruby class objects to do this.
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Let's gloss over the misuse of the 'draw' method, and assume you rename it 'draw_geometry' or some such...
There is still nothing in your code to run that method.Why not add something at the end of both class's initialize code
likeself.draw_geometry()
So when you callEndPulley.new(@st_point)etc the initialize runs and then it gets to do the next step of making geometry without recourse to any additional steps or code...
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conv_group = ents.add_group st_ep, en_epst_epanden_epare instance ofEndPulley- you can't feed that toEntities.add_group.You seem to be confusing Ruby classes with SketchUp entities.
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@dan rathbun said:
(3) What you want to do, is create a Group or Component, that is named "Pulley" and "Conveyor". Perhaps even DynamicComponents.
OK, I see that you ARE actually doing (3), which IS the correct thing to do. (I see that your
drawmethod has nothing to do with theView.draw()method(s), it is just a naming similarity which is best avoided. Methods that create geometry, by convention, we usually prefix with "create_", as increate_end_pully(), etc.)(A) You need to understand that the actual objects you create will be
Sketchup::Groupclass instance objects. So they already HAVE a class identity.You cannot really (or should not actually,) expect that you can assign a class identity to a
Sketchup::Drawingelementsubclass instance object, (or anySketchup::Entitysubclass instance object,) ... and expect the reference to it to be persistent. Sometimes SketchUp reindexes things on the C++ after a save, or purge of layers, etc.
If you close the model, and reopen it, your custom class instances would not be valid.(B) What you attempted to do, is a certain kind of a class implementation, called a "wrapper class." They do have their place, and come in handy sometimes. In this scenario, the custom wrapper class creates an instance of another class, and holds an internal reference the the "wrapped" object, assigned to an instance variable.
Your
Conveyorclass written as a wrapper class, (module wrapped asMagans::Conveyor.)[Semantic Example ONLY. Still needs changes to work properly!]
module Magans class Conveyor # make @group var and .group() instance method; attr_reader(;group) private def initialize(st_point, end_point) @st_point = st_point @end_point = end_point ents = Sketchup.active_model.active_entities pully1 = create_end_pully(ents,@st_point,36,18) pully2 = create_end_pully(ents,@end_point,36,18) # hold reference to group; @group = ents.add_group( pully1, pully2 ) @group.name = "CONVEYOR ASSY" end #of initialize() def create_end_pully(ents,pts,width,length) pt1 =[pts[0] - (width/2),pts[1],pts[2]] pt2 =[pts[0] - (width/2),pts[1]+length,pts[2]] pt3 =[pts[0] + (width/2),pts[1]+length,pts[2]] pt4 =[pts[0] + (width/2),pts[1],pts[2]] face = ents.add_face( pt1,pt2,pt3,pt4 ) group = ents.add_group( face ) group.name = "END PULLEY" face.reverse! face.pushpull( 5 ) # return the pully's group reference; return group end #of create_end_pully() public # Example "wrapper" methods def name() return @group.name end #of name() def valid?() return @group.valid? end #of name() end #of Conveyor class end # module Magans(C) try to use
Sketchup.active_model.active_entitiesso you can add things into the current editing context (which can be the model, or some nesting level within a group or componet instance.)(D) Choose a toplevel namespace module name. (The
Magansname above is an example.) All your code should run within that namespace. You'll likely be wanted to wrap each of your plugin projects within a submodule of you namespace.
You decide on a unique toplevel module (your company name, or your SCF member "screen name".) -
There is still a basic grouping protocol steps that are out of sequence in your original example, and in mine above.
Can you figure out what the proper sequence is ???
(If not... say so, we'll show you what the proper sequence is.)
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Also - when creating Group with the API you create the group first - then add the entities directly into the group. As oppose to when you model in SketchUp where you draw the geometry - then group.
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You CAN make a group from existing entities
gp=entities.add_group(array_of_entities)... BUT if those entities are not all in the same context OR if their context is NOT the active_entities then you will get a Bugsplat.
If you are making new entities then it is best to make them inside the desired context in the first place - using a new [initially] empty groupgp=entities.add_group();gp.entities.add_face(points)to get the face etc.
Doing this also removes the risk of your new geometry clashing with some existing geometry in the active_context - e.g. overlapping faces, which will intersect unexpectedly if not separated from the very creation of your new face.
The only time I would suggest you want even to think about making a group from existing objects... is when you are using a user's [premade] selection - because they can only select objects in the 'active_entities' context then you can safely group those objects [or a filtered sub-set of them - e.g. just faces and edges] into a new group that is made in the same context, thus:gp=model.active_entities.add_group(model.selection.to_a)will make a group of the current selection. -
@dan rathbun said:
There is still a basic grouping protocol steps that are out of sequence in your original example, and in mine above.
Can you figure out what the proper sequence is ???
@thomthom said:
... when creating Group with the API you create the group first - then add the entities directly into the group. As oppose to when you model in SketchUp where you draw the geometry - then group.
Thomas gave away the answer.
So ... lets see the my example, using this protocol.
We will first create the conveyor group, add a temporary construction point to it, so SU does not clean it up, then past that parent group's
entitiesreference into the other method, and have the subordinate method add it's subgroup to the parent group. Finally we will add pully primitives to the subgroup and return it's reference.module Magans class Conveyor # make @group var and .group() instance method; attr_reader(;group) private def initialize(st_point, end_point) @st_point = st_point @end_point = end_point ents = Sketchup.active_model.active_entities # hold reference to group; @group = ents.add_group() cpt = @group.entities.add_cpoint(ORIGIN) @group.name = "CONVEYOR ASSY" # pully1 create_end_pully(@group.entities,@st_point,36,18) # pully2 create_end_pully(@group.entities,@end_point,36,18) cpt.erase! end #of initialize() def create_end_pully(ents,pts,width,length) pt1 =[pts[0] - (width/2),pts[1],pts[2]] pt2 =[pts[0] - (width/2),pts[1]+length,pts[2]] pt3 =[pts[0] + (width/2),pts[1]+length,pts[2]] pt4 =[pts[0] + (width/2),pts[1],pts[2]] subgroup = ents.add_group() face = subgroup.entities.add_face( pt1,pt2,pt3,pt4 ) subgroup.name = "END PULLEY" face.reverse! face.pushpull( 5 ) # return the pully's group reference; return subgroup end #of create_end_pully() public # Example "wrapper" methods def name() return @group.name end #of name() def valid?() return @group.valid? end #of name() end #of Conveyor class end # module Magans -
First of all I would like to thank you guys for all of the help. My thought process was skewed in the wrong direction and I don't think I would've come up with the passing the group object. Also starting with the group and then adding the entities is now clear in my head. I had read that before in other posts but could never quite understand the "how". That was where I was hopelessly stuck for the past day. I have re-written the previous code and module-ized it and it works perfectly.
I kept the classes for Conveyor and EndPulley seperate so that I can use both seperately for inheritance in the future.
I still need to check into "Wrapper" classes further for how I can implement them effectively.
The only snag was I had to remove the private designation for the methods under the Conveyor class to work. I'm not really certain why.
module Pmagans # Type in Console # load 'Conveyor/CONVEYOR2.rb' # conv = Pmagans;;Conveyor.new([0,0,0], [0,120,0]) class Conveyor #make the @group var and .group()instance attr_reader(;group) #private #why does this need to be private? def initialize(st_point, end_point) ents = Sketchup.active_model.entities @st_point = st_point @end_point = end_point #hold reference to group; @group = ents.add_group() cpt = @group.entities.add_cpoint(ORIGIN) @group.name = "CONVEYOR ASSY" self.create_geometry cpt.erase! end #of initialize() def create_geometry() ents = Sketchup.active_model.entities puts ents.length #pulley 1 st_ep = EndPulley.new(@group, @st_point) #pulley 2 end_ep = EndPulley.new(@group, @end_point) puts ents.length end #of create_geometry() end #of Conveyor class class EndPulley attr_reader(;group) def initialize(conv_group, ins_pt) #TODO; add *args if a group not passed to EndPulley just "create_geometry" @conv_group = conv_group @ins_pt = ins_pt self.create_geometry end #of initialize() def create_geometry() pts = @ins_pt width = 36 length = 18 ents = Sketchup.active_model.entities pt1 =[pts[0] - (width/2),pts[1],pts[2]] pt2 =[pts[0] - (width/2),pts[1]+length,pts[2]] pt3 =[pts[0] + (width/2),pts[1]+length,pts[2]] pt4 =[pts[0] + (width/2),pts[1],pts[2]] @group = @conv_group.entities.add_group() face = @group.entities.add_face pt1,pt2,pt3,pt4 face.reverse! face.pushpull 5 @group.name = "END PULLEY" end #of create_geometry() end #of EndPulley class end #of module Pmagans -
I'm not sure if my last post went through. I wanted to thank everyone though. Also I got everything working and kept the two classes seperate for future inheritence. I had to remove the "private" so that the methods for the Conveyor class could be accessed. I'm not really sure why?
module CONVEYOR #CONVEYOR.rb # Type in Console # load 'Conveyor/CONVEYOR2.rb' # ex. conv = CONVEYOR;;Conveyor.new([0,0,0], [0,120,0]) require 'sketchup.rb' class Conveyor #make the @group var and .group()instance attr_reader(;group) #private #why does this need to be private? def initialize(st_point, end_point) ents = Sketchup.active_model.entities t1 = Geom;;Transformation.translation [0,0,-5] @st_point = st_point @end_point = end_point #hold reference to group; @group = ents.add_group() cpt = @group.entities.add_cpoint(ORIGIN) @group.name = "CONVEYOR ASSY" @group.transform! t1 self.create_geometry cpt.erase! end #of initialize() def create_geometry() ents = Sketchup.active_model.entities puts ents.length #pulley 1 st_ep = EndPulley.new(@group, @st_point) #pulley 2 end_ep = EndPulley.new(@group, @end_point) puts ents.length end #of create_geometry() end #of Conveyor class class EndPulley attr_reader(;group) def initialize(conv_group, ins_pt) #TODO; add *args if a group not passed to EndPulley just "create_geometry" @conv_group = conv_group @ins_pt = ins_pt self.create_geometry end #of initialize() def create_geometry() pts = @ins_pt width = 36 length = 18 ents = Sketchup.active_model.entities pt1 =[pts[0] - (width/2),pts[1],pts[2]] pt2 =[pts[0] - (width/2),pts[1]+length,pts[2]] pt3 =[pts[0] + (width/2),pts[1]+length,pts[2]] pt4 =[pts[0] + (width/2),pts[1],pts[2]] @group = @conv_group.entities.add_group() face = @group.entities.add_face pt1,pt2,pt3,pt4 face.reverse! face.pushpull 5 @group.name = "END PULLEY" end #of create_geometry() end #of EndPulley class end #of module CONVEYOR -
@pmagans said:
I'm not sure if my last post went through.
The first few posts of new members must be approved by a moderator before it appear on the forum - this is an anti-spam measure.
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You still have this
st_ep = EndPulley.new(@group, @st_point)
which won't return the new object [group] unless you add
return @group
as the final code in the EndPulley method... -
So I added the return @group per your recommendation TIG however I am having some confusion as to how Sketchup sees the newly created groups. It doesn't seem like you can manipulate the returned groups as per the example code below returns undefined method transform!
It seems as though Sketchup is treating the groups st_ep and end_ep as objects not groups. I have been creating "dummy-container groups to bypass this like Conveyor but I'm guessing from your comment there is an easier way to access the groups that I am creating in the EndPulley class?module CONVEYOR #CONVEYOR.rb # Type in Console # load 'Conveyor/CONVEYOR2.rb' # ex. conv = CONVEYOR;;Conveyor.new([0,0,0], [0,120,0]) require 'sketchup.rb' class Conveyor #make the @group var and .group()instance attr_reader(;group) #private #why does this need to be private? def initialize(st_point, end_point) ents = Sketchup.active_model.entities #t1 = Geom;;Transformation.translation [0,0,-5] @st_point = st_point @end_point = end_point #hold reference to group; @group = ents.add_group() cpt = @group.entities.add_cpoint(ORIGIN) @group.name = "CONVEYOR ASSY" #@group.transform! t1 self.create_geometry cpt.erase! end #of initialize() def create_geometry() ents = Sketchup.active_model.entities t1 = Geom;;Transformation.translation [0,0,-5] #pulley 1 st_ep = EndPulley.new(@group, @st_point) #puts st_ep st_ep.transform! t1 #pulley 2 end_ep = EndPulley.new(@group, @end_point) end_ep.transform! t1 end #of create_geometry() end #of Conveyor class class EndPulley attr_reader(;group) def initialize(conv_group, ins_pt) #TODO; add *args if a group not passed to EndPulley just "create_geometry" @conv_group = conv_group @ins_pt = ins_pt self.create_geometry end #of initialize() def create_geometry() pts = @ins_pt width = 36 length = 18 ents = Sketchup.active_model.entities pt1 =[pts[0] - (width/2),pts[1],pts[2]] pt2 =[pts[0] - (width/2),pts[1]+length,pts[2]] pt3 =[pts[0] + (width/2),pts[1]+length,pts[2]] pt4 =[pts[0] + (width/2),pts[1],pts[2]] @group = @conv_group.entities.add_group() face = @group.entities.add_face pt1,pt2,pt3,pt4 face.reverse! face.pushpull 5 @group.name = "END PULLEY" return @group end #of create_geometry() end #of EndPulley class end #of module CONVEYOR -
end_ep = EndPulley.new(@group, @end_point)NOW ADD
puts 'end_tp details...' puts end_tp puts end_tp.class puts end_tp.name puts 'END'THEN
end_ep.transform!(t1)FAIL ? IF end_tp is NOT a group or component_instance ???
Report back what the 'puts' show in the Ruby Console...
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This is the output - Doesn't get to the puts statements
load 'Conveyor/CONVEYOR2.rb' true conv = CONVEYOR;;Conveyor.new([0,0,0], [0,120,0]) end_tp details... Error; #<NameError; undefined local variable or method `end_tp' for #<CONVEYOR;;Conveyor;0xb8a563c>> C;/PROGRA~2/Google/GOOGLE~1/Plugins/Conveyor/CONVEYOR2.rb;43 C;/PROGRA~2/Google/GOOGLE~1/Plugins/Conveyor/CONVEYOR2.rb;27;in `initialize' (eval);435;in `new' (eval);435 -
Try this change: in the EndPulley code after
self.create_geometry
###ADD
return @groupas the last code before the '
end' of theinitialize...REMOVE the equivalent line from the
create_geometrymethod...Run with the '
puts' to see what's what now... -
Same message No change - its dying on the puts statements?
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WAIT !!
Earlier on I attempted to explain that his custom classes were WRAPPER CLASSES. (And questioned why anyone would want to actually do this. Subsequent edits by a user such as boolean operations can cause the references held by the wrapper class instances to become invalid and point at
Sketchup::DeletedEntityobjects.)I showed an example which did NOT have a
EndPullyclass, because it would ALSO be a wrapper class, whosenew()constructor returns the wrapper instance NOT aSketchup::Groupinstance.SO.. therefore... he needs to call the
EndPullyinstance'sgroup()wrapper method (created via theattr_reader(:group)call,) which will return the actual group reference:
st_ep.group.transform! t1 -
Can you also add the equivalent 'puts' just after the
st_ep = EndPulley.new(@group, @st_point)puts 'st_tp details...' puts st_tp puts st_tp.class puts st_tp.name puts 'END'so we can see what the first part does...
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