Re: [BuildStream] Proposal: bst artifact subcommand group

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

On Fri, 2018-11-30 at 14:40 -0500, Chandan Singh wrote:
> Hi Richard,
[...]
> > To not duplicate the logic we need to either turn our Artifacts into "Elements",
> > or re-architect to expose interfaces that operate on Artifacts
> > and handle Elements by turning them into Artifacts first.
> >
> > I looked at turning Artifacts into "Elements",
> > which could be done with custom Project and Loader classes,
> > but it looks to be more work than I've time for before 1.4.
> >
> > If `bst checkout` is going to be deprecated in 1.4
> > you won't be able to use the options for running integration commands
> > or whether to include dependencies when specifying an element name.
>
> I am slightly confused by this, i.e. why wouldn't it be possible to
> specify the dependencies of an element when working with element
> names?
>
> Shouldn't it be possible to load the element first, figure out the
> list of dependencies involved, calculate the cache keys for them, and
> then checkout all those artifacts? Or maybe I misunderstood
> something...

+1

I think that if we are moving the checkout logic to the `bst artifact`
subgroup, it does not mean that we are removing the ability of
addressing the elements by their name and loading the data model via
the project data through this CLI interface.

I think we also agreed that loading the data model through the
artifacts instead of through the project data was probably too much
work to land in 1.4, it will probably require some additions to the
artifact metadata, like encoding the original, resolved sources which
went into the artifact for instance (which I think is desirable for
other reasons anyway).

Cheers,
    -Tristan