Function interface vs. Constructable

[rbri]

While working on the Proxy support i stumbled over some places where we check for instanceof Function and then casting to Function but only calling the construct method on the casted object. This is a problem if we are working with Lambda constructors because they are only implementing Constructable.

What do you think - should we change at least the places where Constructable is sufficient (guess ~5 palces)?

[p-bakker]

Sounds like it would fix an issue (when using Lambda constructors) without there being any downside, no?

If so, I'd say it makes sense to make such a change

[gbrail]

I'm trying to make some of the standard objects use lambdas, and finding that I have to change some stuff there. Let me make a PR and we can see if that factors in to what you need to do. But yes we should do this!

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On Wed, Aug 21, 2024 at 9:19 AM Paul Bakker ***@***.***> wrote: Sounds like it would fix an issue (when using Lambda constructors) without there being any downside, no? If so, I'd say it makes sense to make such a change — Reply to this email directly, view it on GitHub <#1376 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAD7I2YJ7EBLU3I2W654YQDZSS427AVCNFSM6AAAAABM4L5IPGVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDGMBSGQ4DGOJYGU> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[rbri]

Ok, will wait for your stuff and see...

[rbri]

@gbrail do you think about the Constructable interface as part of this. Just noted that Function extends Constructable. My feeling (at least for the depending lambda stuff) is that we are in trouble here. I guess only lambda constructor has to fulfill this interface and not Lambda function. Correct?

Or you are aware of an different way to figure out if a function is a ctor?

[gbrail]

Can you do two things for me, and I'm sorry I haven't focused as much on this so far:

First, background: I added Constructable as a "single-function interface." That way both Constructable and Callable are interfaces that you can pass a lambda function to. That's why we have that.

Second, LambdaConstructor implements both Constructable and Callable, because constructors can be invoked either using "new" or directly. It has a flag that you can set to determine whether both methods just call the constructor, or whether one or the other throws an exception.

Finally, I just merged new support into LambdaConstructor so that you can have the Constructable and Callable be different implementations -- I was trying to make the Date class into a lambda and I needed that, because the two forms of the Date constructor do different things.

So -- given all that, do you need to merge #1635? And if you confirm this, then I'm happy to merge it, and I assume that you need it to complete the proxy implementation?

[rbri]

So -- given all that, do you need to merge #1635? And if you confirm this, then I'm happy to merge it, and I assume that you need it to complete the proxy implementation?

No i do not need this for the proxy stuff - there was one place where i had to do the change from Function to Constructable but this is part of the other PR.

The motivation for #1635 was more about using the smallest possible interface - if we only have to call the construct method it is sufficient to check for the Constructable interface.

We can also drop #1635 and wait if we face problems.

[rbri]

@gbrail my real problem with the Reflect/Proxy impl is the implementation of the isConstructor method.

My original plan was to check for the Consturctable interface but this does not work. Maybe you have a better idea.