From 5fcb9284c13e58750ec6c36a1eae5869a5a52925 Mon Sep 17 00:00:00 2001
From: Reinier Zwitserloot canEqual if you change equals and hashCode.
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+ NEW in Lombok 1.14.0: To put annotations on the other parameter of the equals (and, if relevant, canEqual) method, you can use onParam=@__({@AnnotationsHere}). Be careful though! This is an experimental feature. For more details see the documentation on the onX feature.
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- onX was introduced as experimental feature in lombok v0.11.7 (edge release only). + onX was introduced as experimental feature in lombok v0.11.8.
@AllArgsConstructor, @NoArgsConstructor, and @RequiredArgsConstructor support the onConstructor option which will put the listed annotations on the generated constructor.
- @Setter and @Wither support onParam in addition to onMethod; annotations listed will be put on the only parameter that the generated method has.
+ @Setter and @Wither support onParam in addition to onMethod; annotations listed will be put on the only parameter that the generated method has. @EqualsAndHashCode also supports onParam; the listed annotation(s) will be placed on the single parameter of the generated equals method, as well as any generated canEqual method.
The syntax is a little strange; to use any of the 3 onX features, you must wrap the annotations to be applied to the constructor / method / parameter in @__(@AnnotationGoesHere). To apply multiple annotations, use @__({@Annotation1, @Annotation2}). The annotations can themselves obviously have parameters as well.
- The reason of the weird syntax is to make this feature work in javac 7 compilers; the @__ type is an annotation reference to the annotation type _ (underscore) which doesn't actually exist; this makes javac 7 delay aborting the compilation process due to an error because it is possible an annotation processor will later create the _ type. Instead, lombok applies the annotations and removes the references so that the error will never actually occur. The point is: The _ type must not exist, otherwise the feature does not work. In the rare case that the _ type does exist (and is imported or in the package), you can simply add more underscores. Technically any non-existent type would work, but to maintain consistency and readability and catch erroneous use, lombok considers it an error if the 'wrapper' annotation is anything but a series of underscores.
+ The reason of the weird syntax is to make this feature work in javac 7 compilers; the @__ type is an annotation reference to the annotation type __ (double underscore) which doesn't actually exist; this makes javac 7 delay aborting the compilation process due to an error because it is possible an annotation processor will later create the __ type. Instead, lombok applies the annotations and removes the references so that the error will never actually occur. The point is: The __ type must not exist, otherwise the feature does not work. In the rare case that the __ type does exist (and is imported or in the package), you can simply add more underscores. Technically any non-existent type would work, but to maintain consistency and readability and catch erroneous use, lombok considers it an error if the 'wrapper' annotation is anything but a series of underscores.
To reiterate: This feature can disappear at any time; if you use this feature, be prepared to adjust your code when we find a nicer way of implementing this feature, or, if a future version of javac forces us to remove this feature entirely with no alternative.
-- cgit