From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1710 invoked by alias); 17 Sep 2017 15:59:21 -0000 Mailing-List: contact kawa-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: kawa-owner@sourceware.org Received: (qmail 1695 invoked by uid 89); 17 Sep 2017 15:59:20 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.6 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=Methods X-HELO: aibo.runbox.com Received: from dns3.teletopia.net (HELO aibo.runbox.com) (91.220.196.211) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Sun, 17 Sep 2017 15:59:10 +0000 Received: from [10.9.9.212] (helo=mailfront12.runbox.com) by mailtransmit02.runbox with esmtp (Exim 4.86_2) (envelope-from ) id 1dtbyN-0001au-0t; Sun, 17 Sep 2017 17:59:07 +0200 Received: from 70-36-239-177.dsl.dynamic.fusionbroadband.com ([70.36.239.177] helo=localhost.localdomain) by mailfront12.runbox.com with esmtpsa (uid:757155 ) (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.82) id 1dtbyK-0003ie-OR; Sun, 17 Sep 2017 17:59:04 +0200 Subject: Re: using lambda to implement one method interface To: Sonny To , Kawa mailing list References: From: Per Bothner Message-ID: Date: Sun, 17 Sep 2017 15:59:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2017-q3/txt/msg00049.txt.bz2 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/