From d05d03743316e45abfd0d00397999d7eb959eb64 Mon Sep 17 00:00:00 2001 From: Reinier Zwitserloot Date: Mon, 6 Mar 2017 23:34:23 +0100 Subject: Fixed issue #778: problems with onX if the annotation to be added has named args. --- website/features/experimental/onX.html | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'website/features') diff --git a/website/features/experimental/onX.html b/website/features/experimental/onX.html index d4260dd5..39faa1bf 100644 --- a/website/features/experimental/onX.html +++ b/website/features/experimental/onX.html @@ -42,7 +42,9 @@

@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 syntax is a little strange and depends on the javac you are using.
+ On javac7, 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.
+ On javac8 and up, you add an underscore after onMethod, onParam, or onConstructor.

@@ -62,6 +64,8 @@

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.

+ In javac8, the above feature should work but due to a bug in javac8 it does not. However, starting in javac8, if the parameter name does not exist in the annotation type, compilation proceeds to a phase where lombok can fix it. +

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.

The onX parameter is not legal on any type-wide variant. For example, a @Getter annotation on a class does not support onMethod. -- cgit