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Re: NSKeyedArchiver/NSKeyedUnarchiver (was Re: GModel decision)

From: Richard Frith-Macdonald
Subject: Re: NSKeyedArchiver/NSKeyedUnarchiver (was Re: GModel decision)
Date: Tue, 20 Jan 2004 11:12:31 +0000

On 20 Jan 2004, at 02:18, Gregory John Casamento wrote:


Yep ... especially time consuming as we want to reverse engineer the
encoding of the apple classes .. which, as the internal structures of
our classes differ from Apples,  might mean we are archiving different
information to what the current methods do, and reconstructing the
information we need from that.

I believe that, while direct compatibility would be nice, it has the following

1) We would not be directly archiving the structures in our classes and would, instead, be "reconstructing" information when unarchiving or "constructing"
Apple compatible information when archiving.


2) As with Apple's implementation, GNUstep also has some classes which are hidden which are used inside the .gorm file/within classes which are archived. This means that we'll have to know about any and all hidden classes in .nibs to be able to effectively do this. We would also have to be able to transform
the hidden classes we're using into the appropriate ones on MOSX.

Yes.  Though I think that's really  much the same as point 1.

3) Only people who have MOSX would be able to modify the code which
encodes/decodes information in the archive in GNUstep.

Well ... you would need to test/compare with MacOS-X to ensure compatibility, but I think there are plenty of people who would be willing to run test programs on MacOS-X for people wanting to modify the classes who don't have a copy.

4) We would constantly be playing catchup with Apple, if they change their

Yes ... like with all cases of attempting to provide MacOS-X compatibility. I think the encoded representations of MacOS-XD classes are likely to have
a degree of stability comparable with that of the API.

I believe that the correct place for any kind of MOSX<->GNUstep nib/gorm level compatibility belongs in an application or a tool which is specifically made to
transform between the two.

There are just too many differences between the implementations of each to
justify the effort of doing it directly in GNUstep's classes.

My understanding is that Kazunobo pretty much volunteered to attempt to write compatible encoder/decoder code for keyed archives. Certainly there seem to
be people who would like this level of compatibility.

I don't need it myself, but I'm attempting to make the keyed archiver/unarchiver classes capable of being used to read/write MacOS-X archives if the coder/decoder methods available support it. To do otherwise would be to place an unnecessary
barrier in the way of people who do want archive compatibility.

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