Subj : Re: XDR, unimplemented bytecode, JSEqualityOp in JSClass ?
To   : bubbfree
From : Brendan Eich
Date : Fri May 27 2005 11:42 pm

bubbfree@gmail.com wrote:
> I'm encrypting scripts that have been XDR'd for my software so that 3rd
> party authors can securely distribute and sell their scripts to my
> users. The software on the user's side decrypts and runs the script
> from the XDR data.
> 
> This was working fine until I upgraded to the trunk release of
> SpiderMonkey from RC3.  The users (using RC3) get 'unimplemented
> Javascript bytecode 188' with scripts that were XDR'd with the later
> version of SpiderMonkey.
> 
> Is there any way to keep backwards compatibility using XDR?  I have a
> feeling this was because of a change in my class from JSClass to
> JSExtendedClass... needed the JSEqualityOp in JSExtendedClass.


That's not backward compatibility.  Backward compatibility is when you 
run old bytecode on a new engine, and that should work.  What you seem 
to want is forward compatibility, which is new bytecode on an old 
engine, which is nothing we've ever promised.

See http://www.gotdotnet.com/team/changeinfo/default.aspx for 
definitions of backward vs. forward compatibility.


> Is there any way that can I get the equivalent behavior of JSEqualityOp
> in a JSClass ?


This is an unrelated question, right?  Try JSExtendedClass, which must 
have the JSCLASS_IS_EXTENDED flag set.

/be

.