Re: Project options and other format enhancements (and dropping "variants")

[Tristan Van Berkom <tristan vanberkom codethink co uk>]

On Wed, 2017-10-11 at 16:03 +0900, Tristan Van Berkom wrote:
[...]
> The remaining bits which need to be implemented in the context of this
> proposal are the declarative array composition directives (<) (>) and
> (=).

Another progress report.

The above is complete and quite thoroughly regression tested with our
test suite, and documented.

I wanted to hold off on the announcement for the pipelines to run and
for the branch to land on master, but gitlab.com runners seem to be
backed up or not responding for the last couple of hours.

The documentation for the remaining list composition directives will
appear here once they are automatically updated:

   http://buildstream.gitlab.io/buildstream/formatintro.html#format-directives

As a result of the entire change (conditionals, assertions and list
composition directives inclusively), we have accumulated the following
two blockers to the 1.0 release:

  o Remove the 'arches' conditionals

    There is a branch where this is done, it will be landed pending
    migration of the 2 or 3 existing projects which use that, to
    use the new arch project option conditionals instead.

  o Remove pre-/post- commands in any BuildStream elements.

    These are no longer needed.

    Instead of writing:

      config:
        pre-configure-commands:
        - echo "Do something"

    One can use declarative list composition instead:

      config:
        configure-commands:
          (<):
          - echo
"Do something"

    This will be easy to remove from BuildStream, but will also block
    a little on migrating existing projects to use declarative list
    composition instead.


That pretty much closes the book on this thread !

Cheers,
    -Tristan