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  1. Groovy
  2. GROOVY-7654

Iterable as List and Iterable.asList() have different semantics

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 2.4.5
    • Fix Version/s: 2.4.12
    • Component/s: groovy-jdk
    • Labels:
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      Description

      For an Iterable `foo` which is not also a collection, `foo.asList()` and `foo as List` are not equivalent. The latter goes through the asType(Object, Class) path and ultimately returns a proxy. This is unexpected, and can result in some inconsistencies. A simple example:

      class IterableWrapper implements Iterable {
          Iterable delegate
      
          Iterator iterator() {
              delegate.iterator()
          }
      }
      
      def itw = new IterableWrapper(delegate: [1,2,3])
      def itwAsList = itw.asList()
      def itwAsTypeList = itw as List
      assert itwAsList == itwAsTypeList
      assert itwAsList[0] == itwAsTypeList[0]
      

      The first assertion passes, but the second fails with:

      groovy.lang.MissingMethodException: No signature of method: IterableWrapper.get() is applicable for argument types: (java.lang.Integer) values: [0]
      

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              • Assignee:
                paulk Paul King
                Reporter:
                shils Shil Sinha
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                • Created:
                  Updated:
                  Resolved: