Moving ListBase, FixedLengthListMixin and UmodifiableListMixin to collection.

sdk/lib/collection/list.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.collection;
+
+/**
+ * Abstract implementation of a list.
+ *
+ * All operations are defined in terms of `length`, `operator[]`,
+ * `operator[]=` and `length=`, which need to be implemented.
+ */
+typedef ListBase<E> = Object with ListMixin<E>;
+
+/**
+ * Abstract implementation of a fixed-length list.
+ *
+ * All operations are defined in terms of `length`, `operator[]` and
+ * `operator[]=`, which need to be implemented.
+ */
+typedef FixedLengthListBase<E> = ListBase<E> with FixedLengthListMixin<E>;

[floitsch, 2013/04/08 09:41:30]

I'm not sure Lars will like this.
Why not just have one ListBase. Users can then throw on length= (for
FixedLength) and operator[]= (for unmodifiable).

[Lasse Reichstein Nielsen, 2013/04/08 10:17:22]

it's doable, but this is better optimizable and gives better error messages.
The methods on ListBase can be written without assuming that length= might, or
might not, throw, and so they can do other operations before writing to length.
The alternative is that some of them start with "this.length = this.length;" to
ensure early error.

[Lasse Reichstein Nielsen, 2013/04/08 10:22:14]

I can remove FixedLengthListBase and UnmodifiableListBase now, they are not
use/only used inside collection.

+
+/**
+ * Abstract implementation of an unmodifiable list.
+ *
+ * All operations are defined in terms of `length` and `operator[]`,
+ * which need to be implemented.
+ */
+typedef UnmodifiableListBase<E> = ListBase<E> with UnmodifiableListMixin<E>;