Hi Joe,
The changes look sensible to me. Funnily enough, when I read the next, the voice
echoing in my head sounds like Alex's....
A small clarification:
+ * <li> The addition of the additional annotations is both source
+ * compatible and binary compatible. That is, the source containing
+ * the element and its annotations will still compile and the class
+ * file resulting from the compilation will continue to link.
This seems to imply that binary compatibility is with respect to the binary
resulting from having recompiled the source. I have no doubt that such a binary
will link successfully, but that's not quite what I had expected when I read
"binary compatibility".
I would think that binary compatibility in this context would refer to clients
that have *not* been recompiled, but which are linked with a newer version of
the library that has changed to allow repeating annotations. Or perhaps it would
refer to an old class binary that *uses an annotation, being linked with a
library that *defines* that annotation, whose definition has been changed to
allow that annotation to repeat. I don't know if these are real issues, but
they're what came to mind when "binary compatibility" was mentioned.
The statement in the paragraph I quoted above would seem more sensible to me if
the mention of "binary compatible" were struck.
s'marks
On 12/3/13 9:23 PM, Joe Darcy wrote:
Hello,
Please review the patch below to address
JDK-8023471 Add compatibility note to AnnotatedElement
Thanks,
-Joe
diff -r cd4aabc40f72 src/share/classes/java/lang/reflect/AnnotatedElement.java
--- a/src/share/classes/java/lang/reflect/AnnotatedElement.java Tue Dec 03
11:52:18 2013 -0800
+++ b/src/share/classes/java/lang/reflect/AnnotatedElement.java Tue Dec 03
21:23:16 2013 -0800
@@ -135,7 +135,63 @@
* annotations on <i>E</i> are directly present on <i>E</i> in place
* of their container annotation, in the order in which they appear in
* the value element of the container annotation.
-
+ *
+ * <p>There are several compatibility concerns to keep in mind if an
+ * annotation type <i>T</i> is <em>not</em> repeatable in one release
+ * of a library and retrofitted to be repeatable in a subsequent
+ * release.
+ *
+ * <ul>
+ *
+ * <li>If an annotation of type <i>T</i> is present on an
+ * element and <i>T</i> is made repeatable and more annotations of
+ * type <i>T</i> are added to the element:
+ *
+ *
+ * <ul>
+ *
+ * <li> The addition of the additional annotations is both source
+ * compatible and binary compatible. That is, the source containing
+ * the element and its annotations will still compile and the class
+ * file resulting from the compilation will continue to link.
+ *
+ * <li>The addition of the additional annotations is <em>not</em>
+ * behaviorally compatible with respect to the {@code
+ * get[Declared]Annotation(Class<T>)} methods and {@code
+ * get[Declared]Annotations()} methods, because those methods will now
+ * only see a container annotations on the element and not see an
+ * annotation of type <i>T</i>.
+ *
+ * </ul>
+ *
+ * <li>If an annotation type <i>TC</i> is present
+ * on an element, then making some other annotation type <i>T</i>
+ * repeatable with <i>TC</i> as its containing annotation type then:
+ *
+ * <ul>
+ *
+ * <li>The change to <i>T</i>is source and binary compatible with
+ * existing uses of annotations of type <i>T</i> as well as
+ * annotations of type <i>TC</i>.
+ *
+ * <li>The change to <i>T</i> is behaviorally compatible with respect
+ * to the {@code get[Declared]Annotation(Class<T>)} (called with an
+ * argument of <i>T</i> or <i>TC</i>) and {@code
+ * get[Declared]Annotations()} methods because the results of the
+ * methods will not change due to <i>TC</i> becoming the containing
+ * annotation type for <i>T</i>.
+ *
+ * <li>The change to <i>T</i> is <em>not</em> behaviorally compatible
+ * with respect to the {@code
+ * get[Declared]AnnotationsByType(Class<T>)} methods, because those
+ * methods will now recognize an annotation of type <i>TC</i> as a
+ * container annotation and "look through" it to expose annotations of
+ * type <i>T</i>.
+ *
+ * </ul>
+ *
+ * </ul>
+ *
* <p>If an annotation returned by a method in this interface contains
* (directly or indirectly) a {@link Class}-valued member referring to
* a class that is not accessible in this VM, attempting to read the class
