[GROOVY-6966] Type cast methods for Collection

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.4.0-beta-4
• Component/s: groovy-jdk
• Flags: Patch
• Assignee: Cédric Champeau
• Reporter: Yu Kobayashi
• Created: 21/Jul/14 23:54
• Updated: 05/Apr/15 14:43
• Resolved: 10/Nov/14 06:50

Description

This is mainly my fault, current Groovy master branch cannot compile this code in @TypeChecked class,
because Iterable.tail() returns Collection.

void test() {
    assert 2 == foo([1, 2].tail())
}

int foo(List<Integer> a) { 
	a[0] 
}

There is List.tail(), which returns List, but this method is @Deprecated,
and @Deprecated method is not called.

So I created a patch, in which many List methods return List, and also for many other Collection classes.
For example, now List.leftShift() returns List, this code can be compiled in @TypeChecked class.

([1, 2] << 3).each { println it }.collect { it + 1 }.subList(1, 2)

The implementation of List.leftShift() is just this. Only type casts.

public static <T> List<T> leftShift(List<T> self, T value) {
    return (List<T>) leftShift((Collection<T>) self, value);
}

The pull request is here.
https://github.com/groovy/groovy-core/pull/487