[GROOVY-7654] Iterable as List and Iterable.asList() have different semantics

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.5
• Fix Version/s: 2.4.12
• Component/s: groovy-jdk
• Assignee: Paul King
• Reporter: Shil Sinha
• Created: 01/Nov/15 17:10
• Updated: 06/Mar/18 23:14
• Resolved: 13/Jun/17 06:18

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]

Issue Links

• links to: GitHub Pull Request #546