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| /////////////////////////////////////////////////////////////// |
| |
| [[howto-create-sideeffect,Create a SideEffect]] |
| = Create a SideEffect = |
| |
| SideEffects are defined in <<def-sideeffect>>. |
| |
| If you want to reproduce what's explained in this tutorial, remember to depend on the Core Bootstrap artifact: |
| |
| include::../../../../core/bootstrap/build/docs/buildinfo/artifact.txt[] |
| |
| At runtime you will need the Core Runtime artifact too. See the <<howto-depend-on-zest>> tutorial for details. |
| |
| == Typed SideEffect == |
| |
| A typed SideEffect is a Java class that implements the MixinType it can be used on: |
| |
| [snippet,java] |
| ----------- |
| source=tutorials/introduction/tenminutes/src/main/java/org/qi4j/demo/tenminute/MailNotifySideEffect.java |
| tag=allClass |
| ----------- |
| |
| The MailNotifySideEffect is implemented as an abstract class, since we are not interested in the many other methods in |
| the Confirmable interface. Extending the SideEffectOf is a convenience mechanism, instead of an explicit @SideEffectFor |
| annotation on a private field, which can be used in rare occasions when you are not able to extend. This base class |
| defines the next field, which is set up by the Zestâ„¢ runtime and points to the next fragment in the call stack. We can |
| also see that the MailService, HasLineItems and HasCustomer are provided to the side-effect, which is done with |
| dependency injection. Zestâ„¢ also supports dependency injection via constructors and methods. |
| |
| It can be used as follows; |
| |
| [snippet,java] |
| ----------- |
| source=manual/src/main/java/org/qi4j/manual/recipes/sideeffects/OrderEntity.java |
| tag=body |
| ----------- |
| |
| Methods of the SideEffect Fragment will be called after the Mixin invocation. |
| |
| == Generic SideEffect == |
| |
| A generic SideEffect is a Java class that implements java.lang.reflect.InvocationHandler which allows it to be used on any |
| arbitrary MixinType. |
| |
| [snippet,java] |
| ----------- |
| source=manual/src/main/java/org/qi4j/manual/recipes/sideeffects/MyGenericSideEffect.java |
| tag=body |
| ----------- |
| |
| It can be used as follows; |
| |
| [snippet,java] |
| ----------- |
| source=manual/src/main/java/org/qi4j/manual/recipes/sideeffects/AnyMixinType.java |
| tag=body |
| ----------- |
| |
| Methods of the SideEffect Fragment will be called before the Mixin invocation. |
| |
| |
| === AppliesTo === |
| |
| For generic SideEffects that should only trigger on methods with specific annotations or fulfilling some expression, add |
| @AppliesTo annotation to the SideEffect class which points to either triggering annotation(s), or to AppliesToFilter |
| implementation(s). |
| |
| The SideEffect is invoked if one of the triggering annotations is found or one of the AppliesToFilter accepts the |
| invocation. In other words the AppliesTo arguments are OR'ed. |
| |
| Here is how the declaration goes ; |
| |
| [snippet,java] |
| ----------- |
| source=manual/src/main/java/org/qi4j/manual/recipes/sideeffects/MyGenericSideEffect.java |
| tag=appliesTo |
| ----------- |
| |
| And how to use the annotation ; |
| |
| [snippet,java] |
| ----------- |
| source=manual/src/main/java/org/qi4j/manual/recipes/sideeffects/AnyMixinType.java |
| tag=annotation |
| ----------- |
| |
| Here only the doSomething() method will see the SideEffect applied whereas the doSomethingElse() method won't. |
| |
| Finally here is how to implement an AppliesToFilter: |
| |
| [snippet,java] |
| ----------- |
| source=manual/src/main/java/org/qi4j/manual/recipes/sideeffects/MyAppliesToFilter.java |
| tag=filter |
| ----------- |
| |