sbt-condep-plugin

This plugin adds the ability to have conditional direct dependencies on other projects. By default, conditional dependencies will reference an Ivy (or Maven) artifact, but if you create an appropriately named symlink in your project directory to the depended-upon project, a direct (SBT) dependency will be established on that project. This allows automatic rebuilding of depended-upon projects when running targets in the depending project, and provides a magical "things just get recompiled when they need to" experience, like one gets with IDEs.

Usage

Add the plugin to project/plugins/build.sbt:

resolvers += "Condep repo" at "http://samskivert.github.com/sbt-condep-plugin/maven"

libraryDependencies += "com.samskivert" %% "sbt-condep-plugin" % "1.0"

In your project/Build.scala file, declare and use your conditional dependencies like so:

object MyProjBuild extends Build {
  val condeps = com.samskivert.condep.Depends(
    ("foolib",   null,     "foo.bar" % "foolib" % "1.0-SNAPSHOT"),
    ("bazproj", "subbaz",  "foo.baz" % "bazproj-subbaz" % "1.0-SNAPSHOT"),
    ("bazproj", "testbaz", "foo.baz" % "bazproj-testbaz" % "1.0-SNAPSHOT" % "test")
  )

  lazy val myproj = condeps.addDeps(Project(
    "myproj", file("."), settings = Defaults.defaultSettings ++ Seq(
      name := "myproj",
      // ...
      libraryDependencies ++= condeps.libDeps ++ Seq(
        // non-conditional depends
        "org.specs2" %% "specs2" % "1.6.1"
      )
    )
  ))
}

By default, your project will use the Ivy/Maven artifacts as dependencies, but if you create foolib and bazproj symlinks in your top-level project directory, it will use direct SBT dependencies.

You can confirm that the direct dependencies are working by entering the following into the SBT console:

show myproj/project-dependencies

It will output something like the following:

[info] List(foo.bar:foolib:1.0-SNAPSHOT, foo.baz:bazproj-subbaz:1.0-SNAPSHOT)

Note that the versions in that list will be the versions defined in the SBT build for those projects, which could differ from the versions you specify for your Ivy/Maven artifacts.

Issues

Presently, if you use this plugin to depend on a project which then uses this plugin to depend on some other project, you have to add the transitive union of all condep symlinks to the top-level project, or SBT will become confused.

For example, if project A has a condep on project B which has a condep on project C, then project B will have a symlink to project C, and project A must have a symlink to both projects B and C.

At some point I'll pester mharrah into either showing me the required magic to make things work without the symlink from A to C, or enhancing SBT so that it's possible (as I ran into some apparent limitations when trying to make this work).

License

This code is released under the New BSD License. See LICENSE for details.