Code Examples for

Programming in Scala, Fourth Edition

Return to chapter index

27 Annotations

Sample run of chapter's interpreter examples

27.1 Why have annotations?

27.2 Syntax of annotations


// In file annotations/Deprecation1.scala @deprecated def bigMistake() = //...
// In file annotations/Misc.scala @deprecated class QuickAndDirty { //... }
// In file annotations/Misc.scala (e: @unchecked) match { // non-exhaustive cases... }
@cool val normal = "Hello" @coolerThan(normal) val fonzy = "Heeyyy"
scala> import annotation._ import annotation._ scala> class strategy(arg: Annotation) extends Annotation defined class strategy scala> class delayed extends Annotation defined class delayed scala> @strategy(@delayed) def f() = {} ^ error: illegal start of simple expression scala> @strategy(new delayed) def f() = {} f: ()Unit

27.3 Standard annotations


@deprecated def bigMistake() = //...
// In file annotations/Deprecation2.scala @deprecated("use newShinyMethod() instead") def bigMistake() = //...
$ scalac -deprecation Deprecation2.scala Deprecation2.scala:33: warning: method bigMistake in object Deprecation2 is deprecated: use newShinyMethod() instead bigMistake() ^ one warning found
// In file annotations/Native.scala @native def beginCountdown() = {}

27.4 Conclusion

For more information about Programming in Scala, Fourth Edition (the "Stairway Book"), please visit:

http://www.artima.com/shop/programming_in_scala_4ed

and:

http://booksites.artima.com/programming_in_scala_4ed

Copyright © 2007-2019 Artima, Inc. All rights reserved.

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.