Subj : Using Return value in another script problem
To   : netscape.public.mozilla.jseng
From : Laurent Marzullo
Date : Fri May 28 2004 01:48 pm

Hello,

I've got problem, and I can't figure it out, while using previously JS
script return value in another script (or even when returning from the
executed scrip, just after JS_ExecuteScript return).

Here what I want:


// --- C++
// --- The following structure is the return type of a method.
struct PrtyNameAttr
{
    const char*		mdnm;
    const char*         srnm;
    const char*         frnm;
};


// --- C++
class PrtyFactory
{
    public:
        PrtyNameAttr*	GetDefaultPrtyNameAttr( long long );
};

I then want to be able to use those 2 class into JS.

I've done:
1) 
// For the structure
JSClass     PrtyNameAttrClass  =   {
                "PrtyNameAttr" ,
                0,
                JS_PropertyStub,
                JS_PropertyStub,
                JS_PropertyStub,
                JS_PropertyStub,
                JS_EnumerateStub,
                JS_ResolveStub,
                JS_ConvertStub,
                JS_FinalizeStub
            };
//
JSClass     PrtyFactoryClass  =   {
                "PrtyFactory" ,
                0,
                JS_PropertyStub,
                JS_PropertyStub,
                JS_PropertyStub,
                JS_PropertyStub,
                JS_EnumerateStub,
                JS_ResolveStub,
                JS_ConvertStub,
                JS_FinalizeStub
            };
JSFunctionSpec  PrtyFactoryMethodes[] = {
            { "GetDefaultPrtyNameAttr" , 
               prtyFactory_GetDefaultPrtyNameAttr , 1 , 0 , 0 },
            { 0 , 0 , 0 , 0 , 0 }
        };

2) I've then initialise the context, define/create my object etc. 
3) I then want to
   // --- C++
   // Create a default PrtyFactoryClass object and set it as a property
   // of my global object:
   JSObject*   o = JS_ConstructObject( cx , &PrtyFactoryClass , 0 , 0 );
   // Result = Success
   bool t = JS_DefineProperty( cx , global , "PrtyFactory" ,
                 OBJECT_TO_JSVAL( o ) , 0 , 0 , JSPROP_READONLY );
   // t = true
                                                                                                                                                                 
   jsval   rval;
   JSBool  ok = JS_ExecuteScript( cx , global , js , &rval );
   //
   // The JAVA SCRIPT EXECUTED IS:
   // -----------------------------------------
   //
   // PrtyFactory.GetDefaultPrtyNameAttr( 1 );
   //
   // --- End of JS ---------------------------
   // PrtyFactory is a property of the global object defined above.

   if ( ! ok )
	// JAVA SCRIPT ERROR
   else
   {
       if ( JSVAL_IS_INT( rval ) )
           // JS return an INT
       else if ( JSVAL_IS_OBJECT( rval ) )
           // JS Return an object
   }


   According to my trace, the method is called (The one that respond to
   the GetDefaultPrtyNameAttr method) and return an OBJECT.

   Here what I'm doing in the method:
   
   1) Calling a CORBA Service to retrieve structure information from
      a data base (The structure and value contained are correct).
   2) Creating a  PrtNameAttr object.
        o = JS_ConstructObject( cx , &PrtyNameAttrClass , 0 , 0 );
        if ( o == 0 )
            std::cerr << "    (Error)\n";
        else
            std::cerr << "    (done)\n";
   3) I then defining a property for every field in the structure.

JS_DefineProperty( cx , o , "frnm" , 
        STRING_TO_JSVAL( 
            JS_NewString( cx , frnm, strlen( frnm ) ) ) , 
            0 , 0 , JSPROP_READONLY );
JS_DefineProperty( cx , o , "mdnm" , 
        STRING_TO_JSVAL( 
            JS_NewString( cx , mdnm , strlen( mdnm ) ) ) , 
            0 , 0 , JSPROP_READONLY );
JS_DefineProperty( cx , o , "srnm" , 
        STRING_TO_JSVAL( 
            JS_NewString( cx , srnm , strlen( srnm ) ) ) , 
            0 , 0 , JSPROP_READONLY );

   4) Printing the value of the property here give the correct
      value.

   5) returning the new object
      *rval = OBJECT_TO_JSVAL( o );
      return JS_TRUE;


********
********
********

Here the problem:
When I'm using the return value in the C++ code, and try to print
the one of the property, JS_GetProperty return true but the value
printed is not correct (it's garbage character).

I've tried to add the returned jsval to root with JS_AddRoot, but
I always got the problem.

Could someone help please ?
Thanks you very much
Laurent Marzullo

.