Subj : problem with string objects loosing their properties
To   : netscape.public.mozilla.jseng
From : Helge Hess <helge.hess@skyrix.com>
Date : Fri Jun 20 2003 02:24 pm

Hi,

I'm fighting some problem in my ObjC/JS bridge related to JS string 
objects losing their properties and functions. It only occurs in a 
certain context (difficult to explain), and I'm just searching for 
possible reasons instead of an answer ;-)

OK, this is my test-case (you don't need to understand the ObjC ;-):
---snip---
   id base;

   base = [[Blah alloc] init];
   NSLog(@"base: %@", base);

   NSLog(@"this: %@", [base evaluateScript:@"this" language:SLANG]);
   NSLog(@"typeof this: %@",
	[base evaluateScript:@"typeof this" language:SLANG]);

   NSLog(@"'hello': %@",
	[base evaluateScript:@"'hello'" language:SLANG]);
   NSLog(@"typeof 'hello': %@",
	[base evaluateScript:@"typeof 'hello'" language:SLANG]);
   NSLog(@"'hello'.length: %@",
	[base evaluateScript:@"'hello'.length" language:SLANG]);
   NSLog(@"'hello'.length == null: %@",
	[base evaluateScript:@"'hello'.length==null" language:SLANG]);
---snap---

prints:
---snip---
Jun 20 11:16:37 testjs [22671]: base: <Blah 0x81321a4>
Jun 20 11:16:37 testjs [22671]: this: <Blah 0x81321a4>
Jun 20 11:16:37 testjs [22671]: typeof this: object

Jun 20 11:16:37 testjs [22671]: 'hello': hello
Jun 20 11:16:37 testjs [22671]: typeof 'hello': string
Jun 20 11:16:37 testjs [22671]: 'hello'.length:
Jun 20 11:16:37 testjs [22671]: 'hello'.length == null: 1
---snap---

As one can see in the "typeof 'hello'" 'hello' is a JavaScript string. 
But it doesn't have a 'length' property or the 'length' property is null 
(the same goes for functions like slice()).

I only grasp half of the SpiderMonkey internals - what should I search 
for, I can imagine that:
a) a global-object is not properly set in the JSContext ?
b) the custom "this" object doesn't have a proper "parent" object ?
c) "some" prototype chain of 'hello' is broken ?
d) somehow the standard-classes are not properly initialized
e) ....

What is likely, what could I search for ? What could be broken if a 
typeof reports a 'string' object but the object doesn't have any string 
properties ?

After searching two nights any insight is welcome ;-)

regards,
   Helge

.