package act.app.conf;
/*-
* #%L
* ACT Framework
* %%
* Copyright (C) 2014 - 2017 ActFramework
* %%
* 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.
* #L%
*/
import java.lang.annotation.*;
/**
* This annotation marks a class as auto configured class. E.g
*
* ```java
* {@literal @}AutoConfig("foo") class Foo {
* public static final Const<String> name = $.constant("foo1");
* public static class Bar {
* public static final Const<Integer> limit = $.constant(100);
* }
* ...
* public void x() {
* System.out.println(Foo.name.get());
* System.out.println(Foo.Bar.limit.get());
* }
* }
* ```
*
* As the above classs `Foo` has been annotated with `AutoConfig("foo")`,
* ActFramework will automatically configure the class by setting the
* static field `name` and `Bar.limit` if the following configurations
* exists:
*
* 1. foo.name=foo2
* 2. foo.bar.limit=500
*
* With the above configuration, when calling new Foo().x(), it will print
* out:
*
* ```
* foo2
* 500
* ```
*
* instead of
*
* ```
* foo1
* 100
* ```
*
* *Note* the static fields are populated on {@link act.app.event.AppEventId#START event},
* meaning any logic in your application executed before app start shall NOT refer to
* auto config class's configurable fields
*/
@Documented
@Inherited
@Retention(RetentionPolicy.RUNTIME)
@Target(java.lang.annotation.ElementType.TYPE)
public @interface AutoConfig {
/**
* define namespace of the configuration
*/
String value() default "app";
}