Can't access protected constructor?

[Haoyi Li]

I'm getting the following error trying to convert the examples at [http://www.javablogging.com/dynamic-in-memory-compilation/] to scala. In particular, i converted:

public class ClassFileManager extends ForwardingJavaFileManager {
    public ClassFileManager(StandardJavaFileManager standardManager) {
        super(standardManager);
    }

    ...

}

became

class ClassFileManager(fileManager: StandardJavaFileManager) 
extends ForwardingJavaFileManager(fileManager) {

But then I get

scala: constructor ForwardingJavaFileManager in class ForwardingJavaFileManager cannot be accessed in package svm

 Access to protected constructor ForwardingJavaFileManager not permitted because

 enclosing package svm is not a subclass of 

 class ForwardingJavaFileManager in package tools where target is defined

class ClassFileManager(fileManager: StandardJavaFileManager)

                      ^

Which kind of makes sense, but is also rather odd. For some reason the protected constructor is being called in the scope of the external package (svm) and not in the scope of the class (ClassFileManager). Why is this the case? And is there any idiomatic way of doing this? 

It works in Java, but looking at how many lines of code I saved writing the rest of this in Scala, I'd prefer to keep it in Scala if at all possible.

[Som Snytt]

On Tue, Feb 12, 2013 at 1:28 PM, Haoyi Li <haoy...@gmail.com> wrote:

[snip]

class ClassFileManager(fileManager: StandardJavaFileManager) 
extends ForwardingJavaFileManager(fileManager) {

But then I get

scala: constructor ForwardingJavaFileManager in class ForwardingJavaFileManager cannot be accessed in package svm

 

It is used at: src/compiler/scala/tools/util/Javap.scala


    // manages named arrays of bytes, which might have failed to load
    class JavapFileManager(val managed: Seq[Input])(delegate: JavaFileManager = defaultFileManager)
      extends ForwardingJavaFileManager[JavaFileManager](delegate) {
 

[Haoyi Li]

Strange. When I replaced

extends ForwardingJavaFileManager(fileManager)

with

extends ForwardingJavaFileManager[StandardJavaFileManager](fileManager)

which is what is used in the scala library, the error disappeared, and it compiled. Yay!

The immediate problem is solved. But is this a bug? It seems weird that adding a type parameter (that should have been inferred anyway) should affect the access/visibility of the constructor in any way, but yet here it does.

-Haoyi