Subj : (SpiderMonkey Question) Help calling script functions from C
To   : netscape.public.mozilla.jseng
From : zaphodthefirst@hotmail.com (zaphod)
Date : Thu Oct 02 2003 04:54 pm

Hi,

I want to call several functions from a script and
allow the script to store global variables inbetween
function calls. I have set up a small example where
the C code calls the JS 'setvalue' to store a string
in a script global variable, and then the C code
tries to get the string back though the JS 'getvalue'
function.

I am not sure I am doing this right: I'm creating a
context, a global object, compiling the script, and
expecting the script's functions to be part of the
global object.

When I try this, I get a property count of zero for
the global object, an error report that says
"TypeError: undefined is not a function", and the
first attempted function call fails.

Here is the code (this snippet has been pruned down,
in the real code I check all of the return values from
the JS_* functions and am sure that the runtime,
context and global object are created properly.

char * script =
"  var save;                        \n"
"                                   \n"
"  function setvalue(val) {         \n"
"    save = val;                    \n"
"  }                                \n"
"                                   \n"
"  function getvalue() {            \n"
"    return save;                   \n"
"  }                                \n"
;

JSClass globalclass;

void MyFillClass(JSClass * jsclass, char * name)
{
  memset(jsclass, 0, sizeof(*jsclass));
  jsclass->name = name;
  jsclass->addProperty  = JS_PropertyStub;
  jsclass->delProperty  = JS_PropertyStub;
  jsclass->getProperty  = JS_PropertyStub;
  jsclass->setProperty  = JS_PropertyStub;
  jsclass->enumerate    = JS_EnumerateStub;
  jsclass->resolve      = JS_ResolveStub;
  jsclass->convert      = JS_ConvertStub;
  jsclass->finalize     = JS_FinalizeStub;
}

void MyReporter(JSContext * context, const char * msg, JSErrorReport * report)
{
  printf("MyReporter: error \"%s\" in file \"%s\", text \"%s\", token \"%s\" !",
	 msg, report->filename, report->linebuf, report->tokenptr);
}

void MyMain()
{
  JSRuntime * runtime;
  JSContext * context;
  JSObject  *  global;
  
  runtime = JS_NewRuntime(8388608);
  context = JS_NewContext(runtime, 8192);
  
  JS_SetErrorReporter(context, MyReporter);
  
  MyFillClass(&globalclass, "MyGlobalClass");
  global = JS_NewObject(context, &globalclass, NULL, NULL);
  
  JS_InitStandardClasses(context, global);
  JS_CompileScript(context, global, script, (uintN)strlen(script), "static", 0);
  
  {
    char * str;
    
    jsval argv[2];
    jsval retv;
    
    JSIdArray * arr = JS_Enumerate(context, object);
    printf("global object has %d properties", arr->length);
    
    str = (char *)JS_malloc(context, strlen("Hello World !") + 1);
    strcpy(str, "Hello World !");
    
    argv[0] = STRING_TO_JSVAL(JS_NewString(context, str, strlen(str)));
    if (!JS_CallFunctionName(context, object, "setvalue", 1, argv, &retv)) {
      printf("failed on first call");
      return;
    }
    
    if (!JS_CallFunctionName(context, object, "getvalue", 0, argv, &retv)) {
      printf("failed on second call");
      return;
    }
    
    printf("Round Trip With (%s)", JS_GetStringBytes(JSVAL_TO_STRING(retv)));
  }
  
  JS_DestroyRuntime(runtime);
}


I would greatly appreciate any help, thanks.

.