Re: [BuildStream] plugin as elements

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

Hi Ben,

On Tue, 2020-05-05 at 17:21 +0000, Benjamin Schubert wrote:
> Hey Tristan, Hey all
>
> Thanks for the detailed reply.
>
> I've got some comments inline, but here is a summary and the implementation plan I think is our agreement.
> If that is fine with everyone, I'll create issues about it so we can start implementing all the parts.
>
> Please let me know if something required might not be possible with this solution.
>
> - We can reference plugins with a 'junction' origin. The format is as follow:
>
> ```
> - origin: junction
>   junction: potato-junction.bst
>   elements:
>     - starch
>   sources:
>     - shop
> ```
>
> Plugins referenced like that are loaded in the junction's context. However, all their defaults
> are provided by the project that uses them, as is currently the case for the `pip` and `local`
> sources. If a project wants to share defaults, they can provide an include file.

This looks perfect to me, and will be nice and straight forward to
document and use I think.

[...]
> Fair point. My concern was if a plugin author didn't want to provide a project.conf. However,
> we can compose sources in order to inject one, so the concern is moot.

Genius.

I hadn't thought of this at all, it's always nice to see new useful
things we can do with already existing features :)

Cheers,
    -Tristan