Re: [Gnu-arch-users] Features command for arch

[Johannes Berg]

Tom Lord said:

> Ok, suppose that we accept that.... that still leaves the question of
> what *is* the "features" feature?

I've only been reading this thread now -- but I think you can (and maybe
should) make distinctions between different things.

Essentially, if I read that correctly, what ddaa was saying is that
contracts of specific interfaces that tla offers vary (examples include
command exit status etc).
But what exactly are those interfaces? I think they are:
 * single commands
 * tree and archive versions
 * library versions (if at all)
 * abstract features like space support, file id escaping, ...

Of these, tree and archive versions are already addressed (there are
version files), though the proposed change to move stuff from
{arch}/=tagging-method to ./.arch-inventory would probably go along in a
backward compatible way, but this is easily addressed in tools as well.

I don't know whether there are library version numbers, or if that makes
sense at all.

Single command interfaces should imo be specified within the command, such
as:
$ tla tree-lint --command-version
1
This would catch interface changes like to archive-meta-info while being
much easier to maintain (you maintain this within the command). A more
elaborate CLI (such as testing for a specific version) is of course
possible.

Only the third part -- I think -- needs a features command, and thus makes
it much easier to maintain.

johannes