manifold.ext.delegation.rt.api.link Maven / Gradle / Ivy
/*
* Copyright (c) 2023 - Manifold Systems LLC
*
* 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 manifold.ext.delegation.rt.api;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Use {@code @link} to automatically transfer calls on unimplemented interface methods to fields in the same class.
*
* - Choose between call forwarding and true delegation with {@code @part}
* - Override linked interface methods, optionally using {@link part} classes (solves the Self problem)
* - Share super interface implementations (solves the Diamond problem)
* - Configure class implementation dynamically
*
* Classes and links are many-to-many: Many of a class's interfaces may be linked to a single field. A single class may
* have many linked fields.
*
* Basic usage
*
* class MyClass implements MyInterface {
* @link MyInterface myInterface; // transfers calls on MyInterface to myInterface
*
* public MyClass(MyInterface myInterface) {
* this.myInterface = myInterface; // dynamically configure behavior
* }
* }
*
*/
@Target( ElementType.FIELD )
@Retention( RetentionPolicy.RUNTIME )
public @interface link
{
/**
* Specify interfaces to link. This value overrides the declared type of the field. If no interfaces are specified (default),
* the linked interfaces are derived from the field's declared type.
*/
Class[] value() default {};
/**
* Where interface overlap exists with other links, this list of interfaces resolves which links to use. Otherwise,
* overlapping interfaces are not linked and the class must implement them directly, or it must be declared abstract.
* If two or more links declare to share the same interface, a compiler error results.
*/
Class[] share() default {};
/**
* If true, indicates this link is shared where interface overlap exists with other links. Similar to {@link #share},
* but includes all interfaces from this link that overlap.
*/
boolean shareAll() default false;
}