Merge pull request #349 from cvogt/chris3

various minor changes

3 files changed, 38 insertions, 3 deletions

diff --git a/README.md b/README.md
index c353503..205cc6e 100644
--- a/README.md
+++ b/README.md
@@ -495,3 +495,36 @@ only show first 20 lines of type errors to catch the root ones
 ```
 cbt c 2>&1 | head -n 20
 ```
+
+Inheritance Pittfalls
+---------------------
+```
+trait Shared extends BaseBuild{
+  // this lowers the type from Seq[Dependency] to Seq[DirectoryDependency]
+  override def dependencies = Seq( DirectoryDependency(...) )
+}
+class Build(...) extends Shared{
+  // this now fails because GitDependency is not a DirectoryDependency
+  override def dependencies = Seq( GitDependency(...) )
+}
+// Solution: raise the type explicitly
+trait Shared extends BaseBuild{
+  // this lowers the type from Seq[Dependency] to Seq[DirectoryDependency]
+  override def dependencies: Seq[Dependency] = Seq( DirectoryDependency(...) )
+}
+```
+
+```
+trait Shared extends BaseBuild{
+  override def dependencies: Seq[Dependency] = Seq() // removes all dependencies, does not inclide super.dependencies
+}
+trait SomePlugin extends BaseBuild{
+  // adds a dependency
+  override def dependencies: Seq[Dependency] = super.dependencies ++ Seq( baz )
+}
+class Build(...) extends Shared with SomePlugin{
+  // dependencies does now contain baz here, which can be surprising
+}
+// Solution can be being careful about the order and using traits instead of classes for mixins
+class Build(...) extends SomePlugin with Shared
+```
diff --git a/stage2/BuildBuild.scala b/stage2/BuildBuild.scala
index 9ac631f..d97e186 100644
--- a/stage2/BuildBuild.scala
+++ b/stage2/BuildBuild.scala
@@ -2,6 +2,8 @@ package cbt
 import java.nio.file._
 import java.io.File
 
+class ConcreteBuildBuild(val context: Context) extends BuildBuild
+class ConcreteBuildBuildWithoutEssentials(val context: Context) extends BuildBuildWithoutEssentials
 trait BuildBuild extends BuildBuildWithoutEssentials{
   override def dependencies =
     super.dependencies :+ plugins.essentials
diff --git a/stage2/Lib.scala b/stage2/Lib.scala
index 9e1f824..7adb33e 100644
--- a/stage2/Lib.scala
+++ b/stage2/Lib.scala
@@ -47,9 +47,9 @@ final class Lib(val logger: Logger) extends Stage1Lib(logger){
         || directory == (context.cbtHome ++ "/libraries/eval")
         || directory == (context.cbtHome ++ "/plugins/scalatest")
       )
-        new cbt.BasicBuild( context.copy( workingDirectory = start ) ) with BuildBuildWithoutEssentials
+        new cbt.ConcreteBuildBuildWithoutEssentials( context.copy( workingDirectory = start ) )
       else
-        new cbt.BasicBuild( context.copy( workingDirectory = start ) ) with BuildBuild
+        new cbt.ConcreteBuildBuild( context.copy( workingDirectory = start ) )
     } catch {
       case e:ClassNotFoundException if e.getMessage == buildClassName =>
         throw new Exception(s"no class ${buildClassName} found in " ++ start.string)
@@ -139,7 +139,7 @@ final class Lib(val logger: Logger) extends Stage1Lib(logger){
     (
       (
         if( thisTasks.nonEmpty ){
-          s"""Methods provided by Build ${show}
+          s"""Methods provided by ${show}
 
   ${thisTasks.mkString("  ")}