newformat format change

[John A Meinel]

Robert Collins wrote:
> Hi,
> 	I'm about to change newformat to reduce the duplication of having
> text_version and name_version in inventory entries - it will be just
> 'revision'. This is simpler, and will give us a nice index back from the
> weave TOC to every change that occured to a file, making per file log
> fast.
> 
> Do I need to write a format converter for this. Or put another way - who
> is using newformat for live data ?
> 
> Cheers,
> Rob

Actually, one request that I would like to make (since we are breaking 
all the files anyway) is to put a version number in all of the files 
that we write.

Right now, there is a version in branch-format, and then another one in 
.weave files, but I would like to see something similar in the xml files.

That makes it much easier to not break backwards compatibility because 
you can tell what format a file is in.

The way I see it, we can do it a few different ways. It is a little bit 
complicated by the fact we have to write well formed XML. But we could 
use a processing indicator like <?version 0.4?>

Or we could do:

<revision version="0.5">
	<rev_info id="blahblah" put_stuff="here" />
	<parents>
	</parents>
	<meta-info>
	</meta-info>
</revision>

Same thing for inventories. Since we already have an empty inventory 
tag, we could just do:

<inventory version="0.5">
	<file ... />
	<directory ... />
	...
</inventory>

It would be a minimal change to the inventory schema. It might change 
the revision schema a bit more, but I really think it could be worth it. 
Since it makes maintaining compatibility much easier. (You can start 
reading the entry, and then switch based on what version you read).

Now, it might be that you are thinking to make these files always have a 
fixed version relative to the branch-format. Which is okay, but since 
they are separate files, it would be nice to have a separate version 
declaration.

John
=:->
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