Module variables and nested class

jiminy-billy-bob

Hi guys !

As I said before on the forum, I'm new to ruby. I learned a lot, but despite a decent amount of research, I can't seem to figure this out :

require 'sketchup.rb'

module JBB_MyModule

	@model = Sketchup.active_model
	@layers = @model.layers
	@customVar = #something

	# Some code using these @variables

	class JBB_LP_AppObserver < Sketchup;;AppObserver

		def onNewModel(newModel)  #or onOpenModel
			@model = newModel
			@layers = newModel.layers
			@customVar = #some other thing
		end#def

	end#class

end#module

It's not working. I tried local and class variables, which don't work either. It works with global variables, but obviously I'd like to avoid this. And of course it works using "Sketchup.active_model" each time, but the code becomes messy and unreadable.

What should I do ?

Thanks, jbb

renderiza

Maybe try something like this...


require 'sketchup.rb'

module JBB_MyModule

   class JBB_LP_AppObserver < Sketchup;;AppObserver

      @@model = Sketchup.active_model
      @@layers = @@model.layers
      @@customVar = #something

      def onNewModel(newModel)  #or onOpenModel
         @@model = newModel
         @@layers = newModel.layers
         @@customVar = #some other thing
      end#def
      
      ##########
      # Modify #
      ##########
      if !file_loaded?(__FILE__) #then
         @@jpp_test = UI.menu("Plugins").add_submenu("TEST")
    
         @@jpp_test.add_item('Test') {
            Sketchup.active_model.select_tool JBB_MyModule;;JBB_LP_AppObserver.new
         }

         # Add toolbars
         jpp_test_tb = UI;;Toolbar.new "Test"
         jpp_test_cmd = UI;;Command.new("Test") {
            Sketchup.active_model.select_tool JBB_MyModule;;JBB_LP_AppObserver.new
         }

         # icons toolbar
         jpp_test_cmd.small_icon = "img/jpp_test_1_16.png"
         jpp_test_cmd.large_icon = "img/jpp_test_1_24.png"
         jpp_test_cmd.tooltip = "Test"
         jpp_test_cmd.status_bar_text = "Test"
         jpp_test_cmd.menu_text = "Test"
         jpp_test_tb = jpp_test_tb.add_item jpp_test_cmd
         jpp_test_tb.show

      end

   end#class

end#module

Aerilius

You can use constants for this: Constants are looked up through all parent classes/modules until the first matching is found.


module JBB_MyModule

    self;;MODEL = Sketchup.active_model 
    # self;; makes sure the constant is defined in this module
    # Otherwise we would modify a "global" MODEL constant if someone had defined one.

    class JBB_LP_AppObserver < Sketchup;;AppObserver

        def onNewModel(newModel)
            MODEL = newModel  # or JBB_MyModule;;MODEL
        end#def

    end#class

end#module

jiminy-billy-bob

Thanks guys !

I used constants as Aerilius pointed, but had to use .const_set() for this method to work.

tt_su

Use attr, attr_reader, attr_writer, attr_accessor to create methods to access the module/class's instance variables.

The class << self syntax is needed for modules (class attributes). If you define instance attributes that is not needed.

<span class="syntaxdefault"><br /></span><span class="syntaxkeyword">require&nbsp;</span><span class="syntaxstring">'sketchup.rb'<br /><br /></span><span class="syntaxdefault">module&nbsp;JBB_MyModule<br /><br />&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">@</span><span class="syntaxdefault">model&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">Sketchup</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">active_model<br />&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">@</span><span class="syntaxdefault">layers&nbsp;</span><span class="syntaxkeyword">=&nbsp;@</span><span class="syntaxdefault">model</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">layers<br />&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">@</span><span class="syntaxdefault">customVar&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxcomment">#something<br /><br />&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">class&nbsp;<<&nbsp;</span><span class="syntaxdefault">self<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;attr_accessor&nbsp;</span><span class="syntaxkeyword">;</span><span class="syntaxdefault">model</span><span class="syntaxkeyword">,&nbsp;;</span><span class="syntaxdefault">layer</span><span class="syntaxkeyword">,&nbsp;;</span><span class="syntaxdefault">customVar<br />&nbsp;&nbsp;&nbsp;end<br /><br />&nbsp;&nbsp;&nbsp;</span><span class="syntaxcomment">#&nbsp;Some&nbsp;code&nbsp;using&nbsp;these&nbsp;@variables<br /><br />&nbsp;&nbsp;&nbsp;</span><span class="syntaxkeyword">class&nbsp;</span><span class="syntaxdefault">JBB_LP_AppObserver&nbsp;</span><span class="syntaxkeyword"><&nbsp;</span><span class="syntaxdefault">Sketchup</span><span class="syntaxkeyword">;;</span><span class="syntaxdefault">AppObserver<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;def&nbsp;onNewModel</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">newModel</span><span class="syntaxkeyword">)&nbsp;&nbsp;</span><span class="syntaxcomment">#or&nbsp;onOpenModel<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">JBB_MyModule</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">model&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">newModel<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;JBB_MyModule</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">layers&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxdefault">newModel</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">layers<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;JBB_MyModule</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">customVar&nbsp;</span><span class="syntaxkeyword">=&nbsp;</span><span class="syntaxcomment">#some&nbsp;other&nbsp;thing<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end</span><span class="syntaxcomment">#def<br /><br />&nbsp;&nbsp;&nbsp;</span><span class="syntaxdefault">end</span><span class="syntaxcomment">#class<br /><br /></span><span class="syntaxdefault">end</span><span class="syntaxcomment">#module<br />&nbsp;</span><span class="syntaxdefault"></span>

tt_su

Alternatively, in the case of observers, I usually define methods in the root module which I call from the observers - defining minimum amount of code in the observer class itself.

jiminy-billy-bob

Thanks a lot Thomas ! That was exactly what I was looking for.

@tt_su said:

Alternatively, in the case of observers, I usually define methods in the root module which I call from the observers - defining minimum amount of code in the observer class itself.

For what ? Less bugsplats/erros ?

tt_su

Just because observers doesn't have access to the instance variables of the parent module. All I need observers for are tell when when things change - so I prefer to keep the logic that modifies stuff in the parent module along with the rest of it. It's an organization thing.

Anton_S

Is there any advantages or disadvantages of instance variables over the class variables in the module?

I know a few advantages for using instance vars:

no extra @ symbol
attr_... functions that give simpler organizations

I just wanted to know if there is any difference when it comes to using them in the module context.

tt_su

I don't think class variables in modules has any use.

In general people (when you search the net for Ruby) will advice against class variables if you can avoid them due to that they are troublesome when you create subclasses.

Anton_S

Thank you ThomThom

Moving to instance variables