[darcs-users] "inconsistent" repositories [was buggy darcs_cgi in 0.9.14.15pre-1 ?]

[David Roundy]

On Mon, Dec 08, 2003 at 10:59:47PM +1100, Tim Barbour wrote:
> David Roundy writes:
>  > Hmmmm.  I'll think about whether that might be practical.  As an
>  > interrim measure, I could stick a "converted" file somewhere in
>  > _darcs.  I'd rather not go with the a permantent "repo_format_version"
>  > file, since I don't plan to ever again change the repository format in
>  > a repo-breaking way like this.
> 
> Would a file be enough ? What if someone pulls a patch (I suppose it
> would be rewritten to the current format in transit) ?

Pulling patches is safe in the current transition.  The "dangerous"
transition isn't a change in patch format, but a change in the meaning of a
hunk patch.  Any interchange between 0.9.14 and 0.9.15 is safe, as long as
both versions are using consistent repositories, according to their own
definition of consistent, which differs by one newline at the end of each
file.

> If a file can do the job (rather than putting the info in each patch)
> then perhaps it would be easy to add one.  Of course, handling different
> format version numbers would be more trouble, but if the format version
> never changes this will not be an issue. OTOH, if the format version does
> change again, you might be glad of the file.
> 
> I have always found it hard to predict the future.

In the future (after 1.0) I will never change the meaning of a patch type.
This is a patch type meaning issue, rather than a repository format issue,
and changing the meaning of a primitive patch is almost always a bad idea.
I'd say it's always a bad idea, except that I just did it... but this was a
special case in that the change is such that any patch which is valid with
one meaning is guaranteed to be valid when interpereted in the other way.
-- 
David Roundy
http://www.abridgegame.org