Re: Keyed archiving and class clusters

[David Chisnall]

On 28 Jun 2010, at 15:15, Thomas Davie wrote:

> Hi all,
> 
> From what I understand, GNUstep's keyed archive format is meant to be 
> compatible with Apple's.  

I don't think this is the case, but it's possible.

> However, I'm hitting an issue and I'm not certain if it's the fault of the 
> archiver, or class clusters.
> 
> Basically, when an NSMutableSet gets encoded, what really gets encoded is 
> it's concrete subclass, GSMutableSet... When I try to decode this in some 
> code using apple's implementation, it chokes, not having a GSMutableSet class 
> to attempt to init.

This is expected behaviour.  Archiving is low-level functionality.  You are not 
expected to be able to serialize objects using one Foundation implementation 
and restore them with another, because they contain things like serialized 
ivars.

> Is there any sane way round this, or should I get on with writing my own 
> serialisation methods if I want to send objects back and forth between 
> apple/GNUstep implementations?

You can use NSPropertyListSerialization if you want a format that is 
implementation-agnostic.

David