From: Per Bothner <per@bothner.com>
To: Sonny To <son.c.to@gmail.com>, Kawa mailing list <kawa@sourceware.org>
Subject: Re: using lambda to implement one method interface
Date: Sun, 17 Sep 2017 15:59:00 -0000 [thread overview]
Message-ID: <d3a88010-0cca-4630-6014-4d26ee4a33c2@bothner.com> (raw)
In-Reply-To: <CAJxjsJvoUdTSDrz-n9JwZZ1vhhoDx2inp0+975e+3WF1yv5Vpg@mail.gmail.com>
On 09/17/2017 08:38 AM, Sonny To wrote:
> this works
>
> (let ((handler (android.os.Handler (android.os.Looper:getMainLooper)))
> )
> (handler:post (lambda ()
> (android.util.Log:i "scm" "run me")))
> )
>
> this is non-intuitive. why doesn't it work if i bind the lambda to a
> symbol? seems like a bug to me
Perhaps a documentation bug: It may not be clear that when the manual
say "required type" in:
This is possible when the required type is an interface or
abstract class with a Single (exactly one) Abstract Methods.
we mean the type required by the *compile-time context* of the expression.
This is a deliberate design limitation, not a bug. This way the anonymous
class can be created a compile-time, not run-time. Doing it at run-time
would be more difficult and more expensive. Kawa has always put a high
priority on performance.
Perhaps a future Kawa extension will allow "SAM-conversion" at run-time,
but it is not currently in the plans.
--
--Per Bothner
per@bothner.com http://per.bothner.com/
next prev parent reply other threads:[~2017-09-17 15:59 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-17 15:32 Sonny To
2017-09-17 15:38 ` Sonny To
2017-09-17 15:59 ` Per Bothner [this message]
2017-09-17 16:04 ` Sonny To
2017-09-17 16:50 ` Per Bothner
2017-09-17 18:54 ` Sonny To
2017-09-17 20:02 ` Per Bothner
2017-09-18 6:35 ` Sonny To
2017-09-18 8:17 ` Sonny To
2017-09-18 13:59 ` Per Bothner
2017-09-18 11:22 ` Sudarshan S Chawathe
2017-09-18 14:24 ` Per Bothner
2017-09-18 14:31 ` Sudarshan S Chawathe
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