Subj : Re: Serializing Object Graphs
To   : Eric Brueggemann <eric_brueggemann@yahoo.com>
From : Brendan Eich <brendan@meer.net>
Date : Tue Apr 08 2003 03:46 pm

Eric Brueggemann wrote:

>Brendan Eich wrote:
>  
>
>>Why would you want to use serialization for a "DOM undo" mechanism?  
>>Undo is easily implemented using a log of invertible operations.
>>
>>Mozilla's editor has multi-level undo.  But maybe you're not using Gecko?
>>
>>/be
>>    
>>
>
>Hi,
>
>Well, the DOM doesn't capture all the relevant information. I'd like
>to be able to roll back JSObjects as well:
>
>obj.foo = "bar";
><store rollback point>
>obj.foo = MD5(obj.foo);
><rollback>
>obj.foo == "bar";
>
>It would also be very nice to be able to save state to disk for
>restoration in a later process.
>  
>

Why do you want this, exactly?

Serialization at the native object level requires cooperation by the 
native object's class or object-ops implementation (wherefore 
JSClass.xdrObject and JSObjectOps.xdrObject).  But many classes do not 
fully implement these hooks.  I doubt it's worth the effort trying to 
get all the native ones, just in the core engine, to do so.  Then there 
are all the DOM ones.

Invertible/transactional logging sounds better to me.  But you'd still 
need to record all changes at a low level.  Again, is it worth the high 
cost of implementation effort, and likely high cost in dynamic memory, 
and medium to low cost in code footprint?

/be

.