Re: [RFC PATCH 0/4] pathspec labels [WAS: submodule groups]

On Fri, May 13, 2016 at 7:19 AM, Stefan Beller [off-list ref] wrote:

After some fruitful discussion[1] in which Junio suggested trying a very
different route[2] that is more general and not submodule related, I considered
doing a mock for this.

This lets you label arbitrary pathspecs, e.g. in git.git we may want to have:

    t/t[0-9]*.sh label=tests

such that

    $ git log --author=Beller ":(label=tests)"

would show all commits in which I touched tests.

This has suprisingly few lines of code, as the first 3 patches are refactoring.
The actual new feature is in the last patch.

This would solve the submodule issues I want to solve, as I can produce a
.gitattributes like:

    ./submodule1 label=default
    ./submodule2 label=default
    ./submodule3 label=optional-feature1

and then I'd instruct the users to clone like this:

    git clone .. superproject
    cd superproject
    git submodule update --init :(label:default)

The second part of the submodule series to collapse these three commands
will come as an extra series later, then.

Yeah. I can see the use of this, even without submodules.

What annoys me here:
Attributes can only be set once at the moment, there is no way to collect all
attributes. If we'd have such a collection feature we would be able to
configure this:

    *.[ch] label=C,code
    contrib/** label=oldstuff

Instead of putting everything in under the same attribute name
"label", make one attribute per label? Would this work?

*.[ch] c-group code-group

And the pathspec magic name can be simply "attr", any git attribute
can be used with it, e.g. :(attr:c-group)

and run this:

    git status ":(label:C oldstuff)"

which would be the equivalent to

    contrib/**.[ch]

as in this proposed implementation the labels which are given within one
pathspec item are logical AND. To get the logical OR, you'd have to give multiple
pathspec items, i.e. ":(label:C)" ":(label:oldstuff)"

It's even better if pathspec does not have to deal with combination
logic. Can attr macros deal with that (or if it can't at the moment,
can we improve it)?
-- 
Duy