From 3471b0812792426bf58bd9bab8b7e0ee6d103a7b Mon Sep 17 00:00:00 2001
From: zepumph <michael.kauzmann@colorado.edu>
Date: Fri, 12 May 2017 13:58:35 -0600
Subject: [PATCH] tandemOptional in Property.js, factor
 Optional/RequiredAndNotSupplied into required and supplied options,
 https://github.com/phetsims/scenery-phet/issues/26 2

---
 js/DerivedProperty.js | 7 +++++--
 js/Property.js        | 6 +++---
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/js/DerivedProperty.js b/js/DerivedProperty.js
index b0dae2d2..7bde9ad2 100644
--- a/js/DerivedProperty.js
+++ b/js/DerivedProperty.js
@@ -16,6 +16,7 @@ define( function( require ) {
   var axon = require( 'AXON/axon' );
   var inherit = require( 'PHET_CORE/inherit' );
   var TDerivedProperty = require( 'AXON/TDerivedProperty' );
+  var Tandem = require( 'TANDEM/Tandem' );
 
   function equalsFunction( a, b ) {
     return a === b;
@@ -37,7 +38,9 @@ define( function( require ) {
    */
   function DerivedProperty( dependencies, derivation, options ) {
 
-    options = options || {};
+    options = _.extend( {
+      tandem: Tandem.tandemOptional()
+    }, options );
 
     this.dependencies = dependencies; // @private
 
@@ -69,7 +72,7 @@ define( function( require ) {
     }
 
     // If running as phet-io and a tandem is supplied, register with tandem.
-    options.tandem && options.tandem.addInstance( this, TDerivedProperty( options.phetioValueType ) );
+    options.tandem.supplied && options.tandem.addInstance( this, TDerivedProperty( options.phetioValueType ) );
 
     this.disposeDerivedProperty = function() {
       options.tandem && options.tandem.removeInstance( self );
diff --git a/js/Property.js b/js/Property.js
index dd59ae31..b99d4d13 100644
--- a/js/Property.js
+++ b/js/Property.js
@@ -32,7 +32,7 @@ define( function( require ) {
     }
 
     options = _.extend( {
-      tandem: null, // {Tandem | null}
+      tandem: Tandem.tandemOptional(),
       phetioValueType: null, // {function | null} phet-io type wrapper like TString, TNumber, etc.
 
       // {*[]|null} valid values for this Property. Mutually exclusive with options.isValidValue
@@ -78,7 +78,7 @@ define( function( require ) {
 
     // When running as phet-io, if the tandem is specified, the type must be specified.
     // This assertion helps in instrumenting code that has the tandem but not type
-    Tandem.validationEnabled() && options.tandem && assert && assert( !!options.phetioValueType,
+    Tandem.validationEnabled() && options.tandem.isLegalAndUsable() && assert && assert( !!options.phetioValueType,
       'Type passed to Property must be specified. Tandem.id: ' + options.tandem.id );
 
     // @public (read-only) Emitters that indicate the start/end of processing callbacks for a change.  Also used for PhET-iO data stream
@@ -96,7 +96,7 @@ define( function( require ) {
     this.changedEmitter = new Emitter();
 
     // If running as phet-io and a tandem is supplied, register with tandem.
-    options.tandem && options.tandem.addInstance( this, TProperty( options.phetioValueType, {
+    options.tandem.supplied && options.tandem.addInstance( this, TProperty( options.phetioValueType, {
       phetioInstanceDocumentation: options.phetioInstanceDocumentation,
       phetioStateElement: options.phetioStateElement
     } ) );