Non-monolithic compiler plugins

My plugin is getting too big to fit comfortably in a single class and a single source file. I'd like to split it up, but I'm struggling.

Here's a simple example to illustrate the problem I'm hitting. The following monolithic (but small :-) plugin compiles just fine:

> class TestComponent(plugin: TestPlugin, val global: Global) extends PluginComponent {
>   import global._
>
>   val runsAfter = List[String]("typer")
>   val phaseName = "testphase"
>
>   def newPhase(prev: Phase) = new StdPhase(prev) {
>     def apply(unit: CompilationUnit) {
>       new ForeachTreeTraverser(findAnnotations).traverse(unit.body)
>     }
>   }
>
>   def findAnnotations(tree: Tree) {
>     tree match {
>       case ClassDef(_, _, _, _) if tree.hasSymbol => handleAnnotations(tree.symbol)
>       case _ =>
>     }
>   }
>
>   def handleAnnotations(sym: Symbol) {
>     for (AnnotationInfo(atp, _, _) <- sym.annotations)
>       doSomethingWithAnnotation(sym, atp)
>   }
>
>   def doSomethingWithAnnotation(sym: Symbol, atp: Type) {
>     log("found "+ atp.typeSymbol +" annotation on "+ sym.name)
>   }
> }

But imagine that I want to split the annotation-handling code out into a separate class. Here's my attempt to do so:

> class AnnotationHandler(global: Global) {
>   import global._
>
>   def apply(tree: Tree) {
>     tree match {
>       case ClassDef(_, _, _, _) if tree.hasSymbol => handleAnnotations(tree.symbol)
>       case _ =>
>     }
>   }
>
>   def handleAnnotations(sym: Symbol) {
>     for (AnnotationInfo(atp, _, _) <- sym.annotations)
>       doSomethingWithAnnotation(sym, atp)
>   }
>
>   def doSomethingWithAnnotation(sym: Symbol, atp: Type) {
>     log("found "+ atp.typeSymbol +" annotation on "+ sym.name)
>   }
> }

And I modify findAnnotations to look like:

>   def findAnnotations(tree: Tree) {
>     new AnnotationHandler(global)(tree)
>   }

When I compile, I get:

> [error] /Users/paul/scala/foo/src/main/scala/TestPlugin.scala:31: type mismatch;
> [error]  found   : TestComponent.this.global.Tree
> [error]  required: _1.global.Tree where val _1: com.example.AnnotationHandler
> [error]     new AnnotationHandler(global)(tree)
> [error]                                   ^
> [error] one error found

I assume because the "global" in AnnotationHandler is distinct from the one in TestComponent?

What is the correct way for me to structure things?

--
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On Wednesday 26 October 2011 14:47:18 Paul Butcher wrote:
> What is the correct way for me to structure things?

See this SO question:

http://stackoverflow.com/questions/5629127/splitting-scalac-plugin-into-
multiple-files/5632536

Hope this helps,

Mirko

Mirko, Lukas,

Many thanks - I think that that's given me what I need to find an appropriate solution for my case :-)

On 26 Oct 2011, at 15:18, Mirko Stocker wrote:
> On Wednesday 26 October 2011 14:47:18 Paul Butcher wrote:
>> What is the correct way for me to structure things?
>
> See this SO question:
>
> http://stackoverflow.com/questions/5629127/splitting-scalac-plugin-into-
> multiple-files/5632536
>
> Hope this helps,
>
> Mirko
>