Subcomponent.java

/*
 * Copyright (C) 2015 The Dagger Authors.
 *
 * 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 dagger;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * A subcomponent that inherits the bindings from a parent {@link Component} or
 * {@link Subcomponent}. The details of how to associate a subcomponent with a parent are described
 * in the documentation for {@link Component}.
 *
 * @author Gregory Kick
 * @since 2.0
 */
@Retention(RUNTIME) // Allows runtimes to have specialized behavior interoperating with Dagger.
@Target(TYPE)
@Documented
public @interface Subcomponent {
    /**
     * A list of classes annotated with {@link Module} whose bindings are used to generate the
     * subcomponent implementation.  Note that through the use of {@link Module#includes} the full set
     * of modules used to implement the subcomponent may include more modules that just those listed
     * here.
     */
    Class<?>[] modules() default {};

    /**
     * A builder for a subcomponent.  This follows all the rules of {@link Component.Builder}, except
     * it must appear in classes annotated with {@link Subcomponent} instead of {@code Component}.
     * Components can have methods that return a {@link Subcomponent.Builder}-annotated type,
     * allowing the user to set modules on the subcomponent using their defined API.
     */
    @Target(TYPE)
    @Documented
    @interface Builder {
    }
}