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Wed, 08 Jun 2022 08:09:19 -0700 (PDT) Received: from Taix ([240b:253:ec40:2400:b7d1:436e:2d61:e925]) by smtp.gmail.com with ESMTPSA id m6-20020a1709026bc600b0016370e1af6bsm12073943plt.128.2022.06.08.08.09.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Jun 2022 08:09:19 -0700 (PDT) From: Taiju HIGASHI References: <20220608102124.14865-1-higashi@taiju.info> <87wndrwc5m@nckx> <8735gf47ul.fsf@taiju.info> <87k09rw74q@nckx> Date: Thu, 09 Jun 2022 00:09:16 +0900 In-Reply-To: <87k09rw74q@nckx> (Tobias Geerinckx-Rice's message of "Wed, 08 Jun 2022 16:22:08 +0200") Message-ID: <87sfof19b7.fsf@taiju.info> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Received-SPF: none client-ip=2607:f8b0:4864:20::634; envelope-from=higashi@taiju.info; helo=mail-pl1-x634.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_NONE=0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: guix-patches@gnu.org List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-patches-bounces+larch=yhetil.org@gnu.org Sender: "Guix-patches" X-Migadu-Flow: FLOW_IN X-Migadu-To: larch@yhetil.org X-Migadu-Country: US ARC-Message-Signature: i=1; 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aspmx1.migadu.com; dkim=fail ("headers rsa verify failed") header.d=taiju-info.20210112.gappssmtp.com header.s=20210112 header.b=GlXp3Mhy; dmarc=none; spf=pass (aspmx1.migadu.com: domain of "guix-patches-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="guix-patches-bounces+larch=yhetil.org@gnu.org" X-Migadu-Spam-Score: -0.10 Authentication-Results: aspmx1.migadu.com; dkim=fail ("headers rsa verify failed") header.d=taiju-info.20210112.gappssmtp.com header.s=20210112 header.b=GlXp3Mhy; dmarc=none; spf=pass (aspmx1.migadu.com: domain of "guix-patches-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="guix-patches-bounces+larch=yhetil.org@gnu.org" X-Migadu-Queue-Id: 77E6538CE9 X-Spam-Score: -0.10 X-Migadu-Scanner: scn0.migadu.com X-TUID: YDuVmixH/SwW Hi Tobias, Thank you kindly for your detailed explanation. Tobias Geerinckx-Rice writes: > Hi again, > > Taiju HIGASHI 写道： >> I understand that I can delay the evaluation timing if I make it a >> procedure, but is my understanding correct that the number of calls >> will >> remain the same because it will be evaluated each time the >> `call-with-paginated-output-port` procedure is called? > > Previously, it would have been evaluated even if > call-with-paginated-output-port was never called at all. > > As for the >0 calls case: yes… but when do we expect > call-with-paginated-output-port to be called more than once per run? > > The use case for this code is to do something, then display it in a > pager and exit. I think calling it multiple times in one run would > imply bad UX. > > Do I misunderstand? No, you don't. As you said, my implementation was a bad idea, as call-with-paginated-output-port is executed even when it is not needed. It seems unlikely that call-with-paginated-output-port will be called more than once in a single process. I did not have enough insight. >> I agree with your point that it would be better to make it a >> procedure, >> as it would be more eco-friendly to not have to evaluate when >> GUIX_PAGER >> or PAGER is specified. > > I wish the rest of Guix were so efficient that it mattered :-) > > [/me is waiting for ‘guix pull’ as I reply to multiple mails, on > battery…] > > Regardless, not calling a procedure at all is even more efficient and > IMO more readable here. I agree. >> You mean that the $PATH lookup in open-pipe can be suppressed? > > Yes. OPEN-PIPE* won't need to stat $PATH at all if we give it > "/run/current-system/profile/bin/less" instead of "less". > > (It's not relevant to the above, but my previously reply mistakenly > mentioned a shell ― there is no shell involved with OPEN-PIPE*, only > with OPEN-PIPE. Sorry.) No problem. I'm sorry I'm the one who asked a ton of questions. >> I will just write what you have told me, but may I continue to >> modify >> the patch? > > Of course! Curious how, though. I have also received a response from Maxime and plan to include the following information. (define (find-available-pager) "Returns the program name or path of an available pager. If neither less nor more is installed, return an empty string so that call-with-paginated-output-port will not call pager." (or (getenv "GUIX_PAGER") (getenv "PAGER") (which "less") (which "more") "" ;; Returns an empty string so that call-with-paginated-output-port does not call pager. )) (define* (call-with-paginated-output-port proc #:key (less-options "FrX")) (let ((pager-command-line (find-available-pager))) ... However, I can't submit the v2 patch yet because I don't know how to implement the integration test. Thanks, -- Taiju