Just to follow this up; we have decided to change the signature of
permittedSubclasses to the following:
public Class<?>[] permittedSubclasses() {}
Thanks!
Gavin
> On 8 May 2020, at 23:53, Remi Forax <fo...@univ-mlv.fr> wrote:
>
> The current draft of the reflection API for the sealed keyword adds a method
> getPermittedSubclasses() [1] to java.lang.Class.
>
> I'm not fully sure that returning an array of ClassDesc is the right choice
> here, mainly for two reasons,
>
> 1/ it's weird to return an array of ClassDesc when all others similar methods
> return an array of Class,
> I know why a ClassDesc might be "better" because it avoid the class loading,
> but it also means that now to fully understand java.lang.Class, people has
> to understand how java.lang.constant works.
> The java.lang.constant API was not designed for that, the first line of the
> overview of this package talks about descriptors, constant pool and indy, not
> something beginners should worry about.
>
> 2/ returning a symbolic view (ClassDesc) instead of a Class is *very* error
> prone from a user POV, to resolve a ClassDesc to a class, the user as to
> provide a Lookup
> and there is a good chance that users will pick the wrong ones. The number
> of people that understand classloading and how Lookup works is < 10,
> even experts struggle given the number of time the Lookup API as to be
> patched in recent years. Returning a ClassDesc in this context is like asking
> a child
> to read the serial number of a loaded gun.
> Perhaps a way to mitigate that is to provide the code a user should use to
> get the equivalent classes in the javadoc of getPermittedSubclasses().
>
> cheers,
> Rémi
>
> [1] https://bugs.openjdk.java.net/browse/JDK-8244556
