Mirko Stocker

Move Class, Object and Trait Refactoring for Scala

After lots of bug fixing and improvements of existing refactorings in the Scala IDE, I took a few days off between Christmas and New Year to finally implement a completely new refactoring: Move Class.

Move Class (see Fowler’s description if you’re unfamiliar with it) moves a top-level Class, Object or Trait definition into a different package. And if there exists more than one declaration in the file, you can choose to split-off one of the declarations or to move them all. The refactoring will move all the necessary imports along, and also update all the references to the moved implementation (other imports, or qualified names) in the project.

The refactoring can either be invoked from the menu, or by drag-and-dropping a file in the Package Explorer. Here are some screenshots of the refactoring in action:

It’s also possible to create a new package during the refactoring:

As usual, the changes can be previewed. In this case, the class is removed from the original source file and an import is added to its new location:

Looking at the created file, we see the changed package declaration (a copyright notice in the original file would also have been copied along to the new file) and some imports to types of the originating package:

There are a few limitations: the refactoring works only on Scala code, and it simply ignores visibility issues, so moving might result in compilation errors (cursory tests showed that this also happens in Eclipse JDT — my gold standard for refactoring implementations).

The Move refactoring will be part of the 2.1 release of the Scala IDE, for which there are nightly builds available.

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