org.deephacks.tools4j.config.Config Maven / Gradle / Ivy
/**
* 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 org.deephacks.tools4j.config;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
*
* This annotation is used to mark a classes and fields as configurable and serves as a specification
* of to express the structure, constraints and conditions under which instances can exist to
* fulfill their intended purpose. Instances of configurable classes must always be unique
* with respect to {@link Id}.
*
*
* Changing configuration should never cause system failure or malfunctioning. Configurables should
* therefore make sure that their properties have proper validation rules so that administrators
* does not accidentally misconfigure the system.
*
*
*
* - Fields can be single-valued or multi-valued using any subclass of {@link java.util.Collection} type.
* - Fields can be any subclass of {@link java.util.Map} type, but this is only allowed for
* referencing other {@link Config}, where key is the {@link Id} parameterized as {@link java.lang.String}.
* - Fields can be final in which case it is considered immutable.
* - Fields are not allowed to be transient.
* - Fields are not allowed to be non-final static.
* - Fields can reference other {@link Config} classes, single or multiple using any subclass of
* {@link java.util.Collection} type.
* - Fields can have default values. These are used if no values have been set.
*
* @author Kristoffer Sjogren
*/
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.TYPE, ElementType.FIELD })
@Inherited
public @interface Config {
/**
*
* An informative name that clearly identifies the configuration in the system.
* Good names are those which describe domain specific aspects already established
* in the system architecture.
*
*
* Names will be displayed to administrative users and must be unique within the
* system.
*
* If no name is choosen the field or class name will picked instead.
*
* @return Name of the configurable.
*/
String name() default "";
/**
* An informative description that justify the existence of the configuration,
* putting it into context for how it relates to high-level system concepts and
* ouline what it is used for and how changes affect the behaviour of
* the system.
*
* Descriptions will be displayed to administrative users.
*
* @return A description.
*/
String desc() default "";
}