/*
* Copyright 2015 Google Inc.
*
* 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 jsinterop.annotations;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* JsFunction marks a functional interface as being the definition of a JavaScript function.
*
* <p>There are some limitations exists on JsFunction to make them practical and efficient:
*
* <ul>
* <li>A JsFunction interface cannot extend any other interfaces.
* <li>A class may not implement more than one JsFunction interface.
* <li>A class that implements a JsFunction type cannot be a {@link JsType} (directly or
* indirectly).
* <li>Fields and defender methods of the interfaces should be marked with {@link JsOverlay} and
* cannot be overridden by the implementations.
* </ul>
*
* <p>As a best practice, we also recommend marking JsFunction interfaces with FunctionalInterface
* to get improved checking in IDEs.
*
* <p><b>Instanceof and Castability:</b>
*
* <p>Instanceof and casting for JsFunction is effectively a JavaScript <tt>'typeof'</tt> check to
* determine if the instance is a function.
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
public @interface JsFunction {
}