// Copyright (C) 2012 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.gerrit.client.ui;

public class ListenableOldValue<T> extends ListenableValue<T> {

  private T oldValue;

  public T getOld() {
    return oldValue;
  }

  public void set(final T value) {
    oldValue = get();
    super.set(value);
    oldValue = null; // allow it to be gced before the next event
  }
}

// Copyright (C) 2012 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.gerrit.client.ui;

public class ListenableOldValue<T> extends ListenableValue<T> {

  private T oldValue;

  public T getOld() {
    return oldValue;
  }

  public void set(final T value) {
    try {
      oldValue = get();
      super.set(value);
    } finally {
      oldValue = null; // allow it to be gced before the next event
    }
  }
}

Use try/finally to ensure oldValue is cleared
Use try/finally to ensure oldValue is cleared

If any JS exception is thrown during event delivery the oldValue
should still be set to null to enable garbage collection.

Change-Id: I740db06e93162f86982ffd418c2072bfb4d5d75c
