Script-and-inputOutputField.x3d

<?xml version="1.0" encoding="UTF-8"?>
   <X3D profile='Full' >
 <Scene DEF='scene'>
   <Viewpoint position='20 0 40'/>
   <Shape>
     <Text DEF='text' string='"Initialize called: FALSE" "readFoo() called: FALSE" "foo value send: FALSE" "foo function called: FALSE" "set_foo function called: FALSE" "foo_changed function called: FALSE"'/>
   </Shape>
   <Script DEF='s1' directOutput='true'>
     <field accessType='initializeOnly' name='text' type='SFNode'>
       <Text USE='text'/>
     </field>
     <field accessType='inputOutput' name='foo' type='SFFloat' value='5'/>
     <field accessType='inputOnly' name='readFoo' type='SFTime'/><![CDATA[ecmascript:
 //-----------------------------
 function initialize (value) {
   line = 'Initialized called: TRUE; foo value: ' + foo;
   text.string[0] = line;
  }
 //-----------------------------
 function readFoo (value) {     
  text.string[1] = 'readFoo called: TRUE, value: ' + foo;
 }       
 //-----------------------------
 function foo (value) {     
  text.string[3] = 'foo function called: TRUE; ' + value;
 }       
 //-----------------------------
 function set_foo (value) {     
  text.string[4] = 'set_foo function called: TRUE; ' + value;
 }       
 //-----------------------------
 function foo_changed (value) {     
  text.string[5] = 'foo_changed function called: TRUE; ' + value;
 }       
 ]]>
   </Script>
   <TimeSensor DEF='ts' cycleInterval='3' loop='true'/>
   <Script DEF='s2' directOutput='true'>
     <field accessType='initializeOnly' name='text' type='SFNode'>
       <Text USE='text'/>
     </field>
     <field accessType='inputOnly' name='fooCatcher' type='SFFloat'/><![CDATA[ecmascript:
 //-----------------------
 function fooCatcher (value) {
   text.string[2] = 'Foo value send: TRUE; value: ' + value;
 }
 ]]>
   </Script>
   <ROUTE fromNode='ts' fromField='fraction_changed' toNode='s1' toField='set_foo'/>
   <ROUTE fromNode='ts' fromField='cycleTime' toNode='s1' toField='readFoo'/>
   <ROUTE fromNode='s1' fromField='foo_changed' toNode='s2' toField='fooCatcher'/>
 </Scene>
</X3D>

Browser Results

Browser	Version	Result	Notes
BS Contact	7.107	Not Expected	Follows the X3D-Spec: read on foo gives you the field value, but foo() as function gets also called. Breaks the ECMAScript spec.
FreeWRL		Not Expected	No support for inputOutput
Octaga	2.2.0.12	Not Expected	same as bscontact but addition initialize() is not called. Breaks the ECMAScript spec
Instant Reality	2.0.0_beta4	Not Expected	reading foo returns the function not the field value. foo() funciton gets called. Does not break X3D or ECMA spec but field value is not accessible.
Flux	2.1	Not Expected	reading foo does not work but also no function called ?!?
Vivaty	1.0	Not Expected	reading foo does not work but also no function called ?!?
Xj3D	2_M1_DEV_2008-06_02	Not Expected	the value of foo is the function and the foo() function is not called.

Specification Notes

Basic Problem:

A) The X3D-spec (not VRML) supports intputOutput Fields in Scripts (http://www.web3d.org/x3d/specifications/ISO-IEC-19775-X3DAbstractSpecification_Revision1_to_Part1/Part01/components/scripting.html#Scriptlanguages)

B) Field values can be read or written in the Script code (http://www.web3d.org/x3d/specifications/ISO-IEC-19775-X3DAbstractSpecification_Revision1_to_Part1/Part01/components/scripting.html#Accessingfieldsandevents)

C) Events received by the Script node are passed to the appropriate scripting language method in the script. The method's name depends on the language type used. (http://www.web3d.org/x3d/specifications/ISO-IEC-19775-X3DAbstractSpecification_Revision1_to_Part1/Part01/components/scripting.html#Eventhandling)

D) ECMAScript X3D-binding: If the function represents an inputOutput field, the name of the function shall be the same name as the field declaration, without the set_ or _changed modifiers (http://www.web3d.org/x3d/specifications/ISO-IEC-19777-1-(X3DLanguageBindings-ECMAScript/Part1/concepts.html#ReceivingEvents)

E) ECMAScript: variable and function both are objects in the same namespace. (http://www.ecma-international.org/publications/standards/Ecma-262.htm)

=> There is variable/function-shadowing problem ((E) brakes (D)) which prevents reading/writing (B) or receiving of events (C)

---

Solution:

_S1_) Leave the X3D-Spec like it is (This breaks the ECMAScirpt spec (E))

---

There are ways to abuse the ECMAScript impl. (e.g SpiderMonkey) to work this way but still breaks the spec. (and slows down the object access) However there are some major browser that did exactly this

code snip:

   Script {
   inputOutput SFBool foo TRUE
     ...
     function initialize () {
          Browser.println( 'value: '+ foo);
     }
     ...
     function foo (value,timeStamp) {
         Browser.println( 'value: '+ value);
      }

_S2_) Change the X3D-Spec, use set_foo for the event handler

---

change the name of the function for inputOuput from "same as field" to "set_" prefix

code snip:

   Script {
   inputOutput SFBool foo TRUE
     ...
     function initialize () {
          Browser.println( 'value: '+ foo);
     }
     ...
     function set_foo (value,timeStamp) {
         Browser.println( 'value: '+ value);
      }

_S3_) Change the X3D-Spec, use foo_value/set_foo or foo_changed to access the value

---

change the field-value access funciton

code snip:

   Script {
   inputOutput SFBool foo TRUE
     ...
     function initialize () {
          Browser.println( 'value: '+ foo_value);
     }
     ...
     function foo (value,timeStamp) {
         Browser.println( 'value: '+ value);
      }

---

conclusion:

It is a mess right now and I would suggest that we change the spec to change the event-handling function form foo to set_foo;

Something like:

ECMASCRIPT: 4 Concepts: 4.3.5.4 Receiving events

OLD:

Events sent to the containing node are passed to the corresponding ECMAScript function in the script. The function's name is the same as the field and is passed two arguments. If the function represents an inputOutput field, the name of the function shall be the same name as the field declaration, without the set_ or _changed modifiers

NEW:

Events sent to the containing node are passed to the corresponding ECMAScript function in the script. Two arguments, the value and the timestamp, are passed while calling the function. For inputOnly fields the function's name is the same as the field. If the function represents an inputOutput field, the name of the function shall be the same name as the field declaration plus a set_ prefix.