RequiresOptIn.kt
/*
* Copyright 2020 The Android Open Source Project
*
* 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 androidx.annotation
import kotlin.annotation.Retention
import kotlin.annotation.Target
/**
* Denotes that the annotated element is a marker of an opt-in API.
*
* Any declaration annotated with this marker is considered part of an unstable or otherwise
* non-standard API surface and its call sites should accept the opt-in aspect of it either
* by using [OptIn] or by being annotated with that marker themselves, effectively causing
* further propagation of that opt-in aspect.
*
* Example:
* <pre>`
* // Library code
* @Retention(CLASS)
* @Target({TYPE, METHOD, CONSTRUCTOR, FIELD, PACKAGE})
* @RequiresOptIn(level = Level.ERROR)
* public @interface ExperimentalDateTime {}
*
* @ExperimentalDateTime
* public class DateProvider {
* // ...
* }
`</pre> *
*
* <pre>`
* // Client code
* int getYear() {
* DateProvider provider; // Error: DateProvider is experimental
* // ...
* }
*
* @ExperimentalDateTime
* Date getDate() {
* DateProvider provider; // OK: the function is marked as experimental
* // ...
* }
*
* void displayDate() {
* System.out.println(getDate()); // Error: getDate() is experimental, acceptance is required
* }
`</pre> *
*
* To configure project-wide opt-in, specify the `opt-in` option value in `lint.xml` as a
* comma-delimited list of opted-in annotations:
*
* <pre>`
* @lint>
* @issue id="$issueId">
* @option name="opt-in" value="com.foo.ExperimentalBarAnnotation" />
* @/issue>
* @/lint>
`</pre> *
*/
@Retention(AnnotationRetention.BINARY)
@Target(AnnotationTarget.ANNOTATION_CLASS)
public annotation class RequiresOptIn(
/**
* Defines the reporting level for incorrect usages of this opt-in API.
*/
val level: Level = Level.ERROR
) {
/**
* Severity of the diagnostic that should be reported on usages of opt-in API which did
* not explicitly accept the opt-in aspect of that API either by:
* <ul>
* <li>Propagating the opt-in aspect by annotating the usage with the marker annotation,
* thus becoming part of the marked opt-in API surface <i>or</i>
* <li>Suppressing propagation of the opt-in aspect by annotating the usage with [OptIn]
* and specifying the marker annotation
*/
public enum class Level {
/**
* Specifies that a warning should be reported on incorrect usages of this opt-in API.
*/
WARNING,
/**
* Specifies that an error should be reported on incorrect usages of this opt-in API.
*/
ERROR
}
}