support mill about scala-steward

[nafg]

IIRC mill already has a builtin to check for updates? But it won't rewrite the code will it?

[fthomas]

You can strike point two from your list. scala-steward is build-tool-agnostic when it comes to updating versions in source files. It "just" uses text search and replace to update versions in source files. 3) will be the hard part for which scala-steward uses the sbt-updates plugin.

[nafg]

3 is built into it. mill mill.scalalib.Dependency/updates

[fthomas]

This is great! Then only scala-steward needs be changed to call the right mill commands. I'm looking forward to the PR. :-)

[Baccata]

I had a very quick dive into the code. Is the following analysis correct ?

• The algebra that needs to be provided with an alternate implementation is SbtAlg ?

• SbtAlg currently exposes a reference to ArtificialProject in its interface, the concept of which seems to be fairly coupled to Sbt itself. Maybe ArtificialProject should be a path dependant type both produced and consumed by SbtAlg, so that a similar type can be established for other build tools (if necessary)

• steward currently implements a mechanism that expects the build tool to dump a json representation of the dependencies involved in the repo. Is there an example (or schema) of the json ?

[fthomas]

* The algebra that needs to be provided with an alternate implementation is `SbtAlg` ?

Yes, but you only need to provide alternative implementations for getDependencies and getUpdatesForRepo (this is the most important one).

* SbtAlg currently exposes a reference to `ArtificialProject` in its interface, the concept of which seems to be fairly coupled to Sbt itself.

That's okay. This class is used to find updates of all artifacts scala-steward knows about. We can continue to use that even if we add support for other build tools.

* steward currently implements a mechanism that expects the build tool to dump a json representation of the dependencies involved in the repo. Is there an example (or schema) of the json ?

Here are some examples: https://github.com/fthomas/scala-steward/blob/master/modules/core/src/test/scala/org/scalasteward/core/dependency/parserTest.scala

[joan38]

+1 on this

[fthomas]

FYI: Scala Steward does not need the build system any more for finding dependency updates since #1209. This should make it easier to add support for other build systems. Anyone looking into adding support for Mill should also look into #1193 which adds support for Maven.

[fthomas]

#1429 made adding support for other build system a lot easier. The only thing required now is an implementation of BuildSystemAlg (to get the dependencies from the build) and plugging it into BuildSystemDispatcher.