add doc for all registration of observers, add TODO where dispose is …

…still needed, #78

js/common/model/LineFormsModel.js

@@ -49,7 +49,8 @@ define( function( require ) {
     this.savedLines = new ObservableArray();
     this.standardLines = new ObservableArray();
 
-    // Update the lines seen by the graph. unmultilink unnecessary because we own these Properties.
+    // Update the lines seen by the graph.
+    // unmultilink is unnecessary because we own these Properties, and the model exists for the lifetime of the sim.
     Property.multilink( [ this.interactiveLineProperty, this.savedLines.lengthProperty, this.standardLines.lengthProperty ],
       function() {
         self.graph.lines.clear();

js/common/view/EquationControls.js

@@ -77,6 +77,7 @@ define( function( require ) {
     } );
 
     // Sets the enabled states of the Save and Erase buttons
+    // unmultilink is unnecessary since EquationControls exists for the lifetime of the sim.
     Property.multilink( [ savedLines.lengthProperty, linesVisibleProperty ],
       function() {
         saveLineButton.enabled = linesVisibleProperty.get();

js/common/view/GraphControls.js

@@ -97,21 +97,25 @@ define( function( require ) {
     Panel.call( this, contentNode, options );
 
     // when lines are not visible, hide related controls
+    // unlink is unnecessary since GraphControls exists for the lifetime of the sim.
     linesVisibleProperty.link( function( visible ) {
       notLinesVisibleProperty.set( !visible );
       yEqualsXCheckBox.enabled = visible;
       yEqualsNegativeXCheckBox.enabled = visible;
       slopeCheckBox.enabled = visible;
     } );
 
+    // unlink is unnecessary since GraphControls exists for the lifetime of the sim.
     notLinesVisibleProperty.link( function( visible ) {
       linesVisibleProperty.set( !visible );
     } );
 
+    // unlink is unnecessary since GraphControls exists for the lifetime of the sim.
     gridVisibleProperty.link( function( visible ) {
       notGridVisibleProperty.set( !visible );
     } );
 
+    // unlink is unnecessary since GraphControls exists for the lifetime of the sim.
     notGridVisibleProperty.link( function( visible ) {
       gridVisibleProperty.set( !visible );
     } );
@@ -126,16 +130,19 @@ define( function( require ) {
     };
 
     // Add/remove standard line 'y = x'
+    // unlink is unnecessary since GraphControls exists for the lifetime of the sim.
     yEqualsXVisibleProperty.link( function( visible ) {
       setStandardLineVisible( visible, Line.Y_EQUALS_X_LINE );
     } );
 
     // Add/remove standard line 'y = -x'
+    // unlink is unnecessary since GraphControls exists for the lifetime of the sim.
     yEqualsNegativeXVisibleProperty.link( function( visible ) {
       setStandardLineVisible( visible, Line.Y_EQUALS_NEGATIVE_X_LINE );
     } );
 
     // Select appropriate check boxes when standard lines are added.
+    // removeItemAddedListener is unnecessary since GraphControls exists for the lifetime of the sim.
     standardLines.addItemAddedListener( function( line ) {
       if ( line === Line.Y_EQUALS_X_LINE ) {
         yEqualsXVisibleProperty.set( true );
@@ -146,6 +153,7 @@ define( function( require ) {
     } );
 
     // Deselect appropriate check boxes when standard lines are removed.
+    // removeItemRemovedListener is unnecessary since GraphControls exists for the lifetime of the sim.
     standardLines.addItemRemovedListener( function( line ) {
       if ( line === Line.Y_EQUALS_X_LINE ) {
         yEqualsXVisibleProperty.set( false );

js/common/view/LineFormsGraphNode.js

@@ -57,23 +57,28 @@ define( function( require ) {
     this.addChild( this.slopeToolNode );
 
     // Add/remove standard lines
+    // remove*Listener not needed because LineFormsGraphNode exists for the lifetime of the sim.
     model.standardLines.addItemAddedListener( this.standardLineAdded.bind( this ) );
     model.standardLines.addItemRemovedListener( this.standardLineRemoved.bind( this ) );
 
     // Add/remove saved lines
+    // remove*Listener not needed because LineFormsGraphNode exists for the lifetime of the sim.
     model.savedLines.addItemAddedListener( this.savedLineAdded.bind( this ) );
     model.savedLines.addItemRemovedListener( this.savedLineRemoved.bind( this ) );
 
     // Visibility of lines
+    // unmultilink is unnecessary since LineFormsGraphNode exists for the lifetime of the sim.
     Property.multilink( [ viewProperties.linesVisibleProperty, viewProperties.slopeToolVisibleProperty ],
       this.updateLinesVisibility.bind( this ) );
 
     // Visibility of the grid
+    // unlink is unnecessary since LineFormsGraphNode exists for the lifetime of the sim.
     viewProperties.gridVisibleProperty.link( function( visible ) {
       self.setGridVisible( visible );
     } );
 
     // Visibility of the equation on the interactive line
+    // unlink is unnecessary since LineFormsGraphNode exists for the lifetime of the sim.
     this.viewProperties.interactiveEquationVisibleProperty.link( function( visible ) {
       if ( self.interactiveLineNode ) {
         self.interactiveLineNode.setEquationVisible( visible );

js/linegame/model/BaseGameModel.js

@@ -95,6 +95,7 @@ define( function( require ) {
     this.initChallenges();
 
     // Do this after initChallenges, because this will fire immediately and needs to have an initial set of challenges.
+    // unlink is unnecessary since BaseGameModel exists for the lifetime of the sim.
     this.playStateProperty.link( function( playState ) {
 
       var challengeIndex = self.challengeIndexProperty.get();

js/linegame/model/Challenge.js

@@ -63,6 +63,7 @@ define( function( require ) {
     this.pointTool2 = new PointTool( new Vector2( 7, -13 ), 'down', this.graph.lines, new Bounds2( -15, -14, 11, 11 ) );
 
     // {Line|NotALine} When the guess changes, update the lines that are 'seen' by the point tools.
+    // unlink unnecessary because Challenge owns this Property.
     this.guessProperty.link( this.updateGraphLines.bind( this ) );
   }
 

js/linegame/model/PlaceThePoints.js

@@ -41,6 +41,7 @@ define( function( require ) {
     this.p3Property = new Property( new Vector2( 3, 2 ) );
 
     // update the guess when the points change
+    // unmultilink unnecessary because PlaceThePoints owns these Properties.
     var self = this;
     Property.multilink( [ this.p1Property, this.p2Property, this.p3Property ],
       function( p1, p2, p3 ) {

js/linegame/view/BaseGameScreenView.js

@@ -43,6 +43,7 @@ define( function( require ) {
     this.addChild( this.settingsNode );
 
     // game 'phase' changes
+    // unlink unnecessary because BaseGameScreenView exists for the lifetime of the sim.
     var self = this;
     model.gamePhaseProperty.link( function( gamePhase ) {
       self.settingsNode.visible = ( gamePhase === GamePhase.SETTINGS );

js/linegame/view/PlayNode.js

@@ -59,6 +59,7 @@ define( function( require ) {
     this.addChild( challengeParent );
 
     // Set up a new challenge
+    // unlink unnecessary because PlayNode exists for the lifetime of the sim.
     model.challengeProperty.link( function( challenge ) {
 
       // dispose of view for previous challenge

js/linegame/view/ResultsNode.js

@@ -28,12 +28,14 @@ define( function( require ) {
    */
   function ResultsNode( model, layoutBounds, audioPlayer, rewardFactoryFunctions ) {
 
+    var self = this;
+
     Node.call( this );
 
     this.rewardNode = null; // @private
 
     // show results when we enter this phase
-    var self = this;
+    // unlink unnecessary because ResultsNode exists for the lifetime of the sim.
     model.gamePhaseProperty.link( function( gamePhase ) {
       if ( gamePhase === GamePhase.RESULTS ) {
 

js/pointslope/model/PointSlopeModel.js

@@ -24,6 +24,8 @@ define( function( require ) {
    */
   function PointSlopeModel( interactiveLine, parameterRange ) {
 
+    var self = this;
+
     interactiveLine = interactiveLine || Line.createPointSlope( 1, 2, 3, 4, GLColors.INTERACTIVE_LINE );
     parameterRange = parameterRange || new PointSlopeParameterRange();
 
@@ -36,7 +38,7 @@ define( function( require ) {
     this.runRangeProperty = new Property( this.graph.xRange );
 
     // Dynamically adjust ranges so that variables are constrained to the bounds of the graph.
-    var self = this;
+    // unlink unnecessary because PointSlopeModel exists for the lifetime of the sim.
     this.interactiveLineProperty.link( function( line ) {
       self.x1RangeProperty.set( parameterRange.x1( line, self.graph ) );
       self.y1RangeProperty.set( parameterRange.y1( line, self.graph ) );

js/pointslope/view/PointSlopeEquationNode.js

@@ -354,6 +354,7 @@ define( function( require ) {
       }
     };
 
+    //TODO #78 unmultilink
     // sync the model with the controls
     Property.lazyMultilink( [ x1Property, y1Property, riseProperty, runProperty ],
       function() {
@@ -363,6 +364,7 @@ define( function( require ) {
       }
     );
 
+    //TODO #78 unlink
     // sync the controls and layout with the model
     lineProperty.link( function( line ) {
 
@@ -391,6 +393,8 @@ define( function( require ) {
       self.addChild( undefinedSlopeIndicator );
       undefinedSlopeIndicator.centerX = self.centerX;
       undefinedSlopeIndicator.centerY = fractionLineNode.centerY - self.undefinedSlopeYFudgeFactor;
+
+      //TODO #78 unlink
       lineProperty.link( function( line ) {
         undefinedSlopeIndicator.visible = line.undefinedSlope();
       } );

js/pointslope/view/PointSlopeGraphNode.js

@@ -41,6 +41,7 @@ define( function( require ) {
     this.addChild( slopeManipulator );
 
     // visibility of manipulators
+    // unlink unnecessary because PointSlopeGraphNode exists for the lifetime of the sim.
     viewProperties.linesVisibleProperty.link( function( linesVisible ) {
       x1y1Manipulator.visible = slopeManipulator.visible = linesVisible;
     } );

js/slope/model/SlopeModel.js

@@ -33,6 +33,7 @@ define( function( require ) {
     this.y2RangeProperty = new Property( this.graph.yRange );
 
     // Dynamically adjust ranges so that variables are constrained to the bounds of the graph.
+    // unlink unnecessary because SlopeModel exists for the lifetime of the sim.
     var parameterRange = new SlopeParameterRange();
     this.interactiveLineProperty.link( function( line ) {
       self.x1RangeProperty.set( parameterRange.x1( line, self.graph ) );

js/slope/view/SlopeEquationNode.js

@@ -147,6 +147,7 @@ define( function( require ) {
     parentNode.addChild( unsimplifiedFractionLineNode );
     parentNode.addChild( unsimplifiedRunNode );
 
+    //TODO #78 unmultilink
     // sync the model with the controls
     Property.lazyMultilink( [ x1Property, y1Property, x2Property, y2Property ],
       function() {
@@ -156,6 +157,7 @@ define( function( require ) {
       }
     );
 
+    //TODO #78 unlink
     // sync the controls and layout with the model
     lineProperty.link( function( line ) {
 
@@ -420,6 +422,7 @@ define( function( require ) {
         }
       };
 
+      //TODO #78 unlink
       lineProperty.link( update.bind( this ) );
 
       return equationNode;

js/slope/view/SlopeGraphNode.js

@@ -41,6 +41,7 @@ define( function( require ) {
     this.addChild( x2y2Manipulator );
 
     // visibility of manipulators
+    // unlink unnecessary because SlopeGraphNode exists for the lifetime of the sim.
     viewProperties.linesVisibleProperty.link( function( linesVisible ) {
       x1y1Manipulator.visible = x2y2Manipulator.visible = linesVisible;
     } );

js/slopeintercept/view/SlopeInterceptEquationNode.js

@@ -358,6 +358,7 @@ define( function( require ) {
 
     //***************************************************************
 
+    //TODO #78 unmultilink
     // sync the model with the controls
     Property.lazyMultilink( [ riseProperty, runProperty, yInterceptProperty ],
       function() {
@@ -373,6 +374,7 @@ define( function( require ) {
       }
     );
 
+    //TODO #78 unlink
     // sync the controls and layout with the model
     lineProperty.link( function( line ) {
 
@@ -411,6 +413,8 @@ define( function( require ) {
       self.addChild( undefinedSlopeIndicator );
       undefinedSlopeIndicator.centerX = self.centerX;
       undefinedSlopeIndicator.centerY = slopeFractionLineNode.centerY - self.undefinedSlopeYFudgeFactor;
+
+      //TODO #78 unlink
       lineProperty.link( function( line ) {
         undefinedSlopeIndicator.visible = line.undefinedSlope();
       } );

js/slopeintercept/view/SlopeInterceptGraphNode.js

@@ -41,6 +41,7 @@ define( function( require ) {
     this.addChild( yInterceptManipulator );
 
     // visibility of manipulators
+    // unlink unnecessary because SlopeInterceptGraphNode exists for the lifetime of the sim.
     viewProperties.linesVisibleProperty.link( function( linesVisible ) {
       slopeManipulator.visible = yInterceptManipulator.visible = linesVisible;
     } );