Reflection on records

[Tagir Valeev]

I don't think there are any published JEPs. Here's some information about
the project:
https://openjdk.org/projects/babylon/

On Mon, Dec 1, 2025, 15:08 David Alayachew <davidalayachew at gmail.com> wrote:

> Understood. Thanks for clarifying. For now, I'll hold off on that, as I
> don't know how stable that is, and I don't really want to.build this new
> library off of it. Maybe when the respective JEP goes into preview. Could
> you link me to that JEP, or is there not one yet?
>
> On Mon, Dec 1, 2025, 9:01 AM Tagir Valeev <amaembo at gmail.com> wrote:
>
>> Yes, you have to build it from the Babylon repo.
>>
>> On Mon, Dec 1, 2025, 14:35 David Alayachew <davidalayachew at gmail.com>
>> wrote:
>>
>>> Thanks @Tagir Valeev <amaembo at gmail.com>.
>>>
>>> I am still not great at the stuff Babylon is doing, so I can only
>>> roughly follow along. Regardless, it sounds like this is depending on
>>> Babylon features which have not yet landed in the mainline jdk, yes?
>>>
>>>
>>> On Mon, Dec 1, 2025, 5:22 AM Tagir Valeev <amaembo at gmail.com> wrote:
>>>
>>>> I think this will surely be possible for RecordComponents with code
>>>> reflection (project Babylon), using the syntax you propose.
>>>>
>>>> You can create a quotable function like this:
>>>>
>>>> import jdk.incubator.code.*;
>>>>
>>>> @Reflect
>>>> @FunctionalInterface
>>>> interface Accessor {
>>>>   Object get(Record r);
>>>> }
>>>>
>>>> Then create something like (just a sketch, sorry, I have no time now to
>>>> provide a full-fledged sample):
>>>>
>>>> static RecordComponent foo(Accessor acc) {
>>>>   Quoted q = Op.ofQuotable(acc).orElseThrow();
>>>>   // extract a method handle from q using Babylon API
>>>>   // unreflect it and find the corresponding RecordComponent
>>>> }
>>>>
>>>> With best regards,
>>>> Tagir Valeev
>>>>
>>>> On Sat, Nov 29, 2025 at 8:45 PM David Alayachew <
>>>> davidalayachew at gmail.com> wrote:
>>>>
>>>>> Hello @amber-dev <amber-dev at openjdk.org>,
>>>>>
>>>>> I asked this on core-libs-dev already, but I figured I should ask here
>>>>> too.
>>>>>
>>>>> Let's say I have some record User(String firstName, String lastName)
>>>>> {}.
>>>>>
>>>>> Is there any possible way for me to do the following?
>>>>>
>>>>> java.lang.reflect.RecordComponent firstName = foo(User::firstName);
>>>>>
>>>>> I'll even accept this.
>>>>>
>>>>> java.lang.reflect.Method lastName = foo(User::lastName);
>>>>>
>>>>> Thank you for your time and consideration.
>>>>> David Alayachew
>>>>>
>>>>
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