Re: compatibility between NSKeyedArchiver in GNUstep and OS X

[Richard Frith-Macdonald]

On 16 Feb 2005, at 03:16, Gregory John Casamento wrote:

> Dan,
>
> --- Dan Hitt <hitt@eskimo.com> wrote:
>
> > Both OS X and GNUstep implement NSKeyedArchiver, which for reference
> > allows a graph of objects to be archived.
> >
> > Are the implementations compatibile?
> >
> > That is, if i use NSKeyedArchiver to  archive some data to a file,
> > will the same NSKeyedUnarchiver code i use to read it work for
> > both OS X  and GNUstep?
>
> Full compatibility has not yet been achieved for gui elements.   I 
> believe,
> however, that most of the elements in Foundation/base archive in a way 
> which is
> compatible with Mac OS X.
>
> Richard, can you confirm this??

Yes and no :-)

The archive format itsself is MacOS-X compatible, and it is based on 
property lists,
so all the classes used in property lists are pretty well tested 
(NSString, NSArray, NSDictionary, NSNumber, NSDate, NSData).

In general, keyed archiving methods for other classes have *not* been 
implemented and those
other classes would probably not be written to archives in a form which 
would work on MacOSX.

However, it's unusual to want to archive the other foundation classes 
when writing the
archiving methods of your own classes (and always possible to avoid 
using them).

So, while keyed archiving implementations of other base classes are not 
essential,
it would be nice if people who wanted them could reverse engineer the 
MacOSX and
contribute MacOSX compatible code.
We do not accept keyed archiving implementations unless they are MacOSX 
compatible ...
so any class which has encodeWithCoder: and initWithCoder: methods 
containing
keyed archiving code should be usable in a portable archive.