[GROOVY-4993] @Memoized AST Transformation for Methods

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.2.0-beta-1
• Labels: contrib
• Assignee: Paul King
• Reporter: Nikita Y Volkov
• Created: 30/Aug/11 07:26
• Updated: 10/Jul/13 04:42
• Resolved: 10/Apr/13 05:15

Description

The whole idea is similar to existing great @Lazy annotation, but it differs in concept: instead of being applied to fields it is applied to methods, thus providing a wider field of use. When applied to getters it serves as an alternative to @Lazy, but applied to other methods it provides what @Lazy can't. Thus it eliminates the need for heavy refactoring in certain situations, by simply letting the user add the annotation to the method.

Here is a suggestion of how it could work:

@Cached
T createX() {
  new T(1, 2, 3)
}   

gets transformed into:

private T $createX$result
T $createX() {
  new T(1, 2, 3)
}
T createX() {
  T $result_local = $createX$result
  if ($result_local != null)
    return $result_local
  else {
    synchronized (this) {
      if ($createX$result == null) {
        $createX$result = $createX()
      }
      return $createX$result
    }
  }
}

This whole thing could be extended to cache different results of a method depending on its arguments, but it's a topic for a discussion.