Clojure JIRA

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4.4

649

25-07-2011

[CLJ-871] instant literal http://dev.clojure.org/jira/browse/CLJ-871 Clojure <p>See <a href="http://dev.clojure.org/pages/viewpage.action?pageId=950382">http://dev.clojure.org/pages/viewpage.action?pageId=950382</a> for design discussion.</p> CLJ-871

instant literal

Enhancement Major Closed Completed Unassigned Stuart Halloway Fri, 4 Nov 2011 12:48:37 -0500 Fri, 1 Mar 2013 12:47:08 -0600 Fri, 3 Feb 2012 09:05:21 -0600 Release 1.4 0 1 <p>I have tested patch locally with no Joda, 1.6.2 Joda, and 2.0 Joda. All work as intended in simple invocations.</p> <p>Seeking feedback on </p> <ul> <li>UTC at the door. Goal is to stay out of localization business. Is that a good goal, and is that the right way to achieve it?</li> <li>idiom for dynamically loading code based on whether Joda on classpath</li> <li>idiom for conveying maven classpath into the ant part of the build. People using ant will have to configure path locally to include Joda.</li> </ul> <p>using a bindable var for a read time setting is kind of a drag stuff like:</p> <p>(binding <span class="error">[*instant-reader* some-other-instant-reader]</span><br/> #@2011-11-04T14:42Z)</p> <p>will not have the desired effect, so then what are the use cases for the bindable var? should the repl bind it? should the compiler?</p> <p>dates should always be read and printed as UTC</p> <p>It seems like it would be nice to have time-delta literals as well. My usage cases deal more often with time-deltas applied as intervals or offsets in time. I presume the current scheme doesn't allow for that but could be adjusted. Is that outside of the scope of this discussion?</p> <p>> UTC at the door.</p> <p>No. Offsets are not localization, just arithmetic.</p> <p>>idiom for dynamically loading code based on whether Joda on classpath</p> <p>We'll need more explicit mechanisms for determining the programmatic representation. Dynamic Joda is just to avoid Joda as hard implementation dep.</p> <p>> People using ant will have to configure path locally to include Joda.</p> <p>People using ant = me.</p> <p>This patch implements instant literals of the form <tt>#@yyyy-mm-ddThh:mm:ss.fff+hh:mm</tt> using only classes available in the JRE.</p> <p>clojure.instant provides instant-readers producing instances of three different JDK classes. These functions accept a string representing a timestamp See (doc clojure.instant/parse-timestamp) for details. </p> <ul class="alternate" type="square"> <li>read-instant-date (java.util.Date)</li> <li>read-instant-calendar (java.util.Calendar)</li> <li>read-instant-timestamp (java.sql.Timestamp)</li> </ul> <p>By default *instant-reader* is bound to read-instant-date.</p> <p>print-method and print-dup are provided for all three types.</p> <p>Rough bits include:</p> <p>I'm not yet certain about the exact public interface of clojure.instant. It's clear that read-instant-* need to be visible. It also seems likely that parse-timestamp and validated could usefully support alternate implementations for *instant-reader*.</p> <p>fixup-offset and fixup-nanos are ugly warts necessitated by Java's pathetic built-in support for dates and times (possibly exacerbated by my own misunderstandings of the same).</p> <p>Unit tests are very basic. For example, I'm not testing validated except in the good case where everything is valid.</p> <p>See also <a href="https://github.com/bpsm/clojure/commit/753f991151847df53d624f7c09b7113cd2321793">https://github.com/bpsm/clojure/commit/753f991151847df53d624f7c09b7113cd2321793</a></p> <hr /> <p>I've made a few trivial fixes to doc strings, visible <a href="https://github.com/bpsm/clojure/commits/CLJ-871.1">on my github branch</a>. Those changes will be included when I re-roll the patch it to incorporate any feedback.</p> <p><a href="http://dev.clojure.org/jira/browse/CLJ-871" title="instant literal"><del>CLJ-871</del></a>-data-readers-1.patch</p> <p>An alternative approach. The dynamic Var <tt>*data-readers*</tt> maps keywords to reader functions, triggered by reader syntax <tt>#:keyword</tt>. Default <tt>#:instant</tt> reader takes a vector like <tt><span class="error">[year month day hrs min sec ms]</span></tt>, all components optional.</p> <p>Pros: No string parsing. Extensible.</p> <p>Cons: Clojure 1.2 used the <tt>#:</tt> syntax to print records.</p> <p>Oddly, I made another case for this. My bad. Attached is the updated patch based off of Ben's work. This patch is merged into the tagged literal feature as implemented in v1.4-alpha4. I also fixed a fence-post error and very minor doc problems. The parser currently defaults to constructing j.u.Date instances of the following form:</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>date-year = 4DIGIT date-month = 2DIGIT ; 01-12 date-mday = 2DIGIT ; 01-28, 01-29, 01-30, 01-31 based on ; month/year time-hour = 2DIGIT ; 00-23 time-minute = 2DIGIT ; 00-59 time-second = 2DIGIT ; 00-58, 00-59, 00-60 based on leap second ; rules time-secfrac = '.' 1*DIGIT time-numoffset = ('+' / '-') time-hour ':' time-minute time-offset = 'Z' / time-numoffset time-part = time-hour [ ':' time-minute [ ':' time-second [time-secfrac] [time-offset] ] ] timestamp = date-year [ '-' date-month [ '-' date-mday [ 'T' time-part ] ] ] </pre> </div></div> <p>Or in other words, <a href="http://tools.ietf.org/html/rfc3339">RFC 3339 </a>.</p> <p>2 problems:</p> <p>1. You can't specify an alternate <tt>inst</tt> reader in data_readers.clj. Doing so causes an opaque error when Clojure starts. This is a flaw in <a href="http://dev.clojure.org/jira/browse/CLJ-890" title="Tagged literals in reader"><del>CLJ-890</del></a></p> <p>2. <tt>*data-readers*</tt> is intended to be a map of symbols to Vars, not symbols to functions. This doesn't really matter.</p> <p>New patch <a href="http://dev.clojure.org/jira/browse/CLJ-871" title="instant literal"><del>CLJ-871</del></a>-with-defaults.patch.</p> <p>Fixes problems described in previous comment by adding <tt>default-data-readers</tt> which can be overridden by <tt>*data-readers*</tt>. Also adds documentation for <tt>*data-readers*</tt>.</p> <p>divisible? and indivisible? should be normal functions, not macros. They're used only in leap-year? – it would be pretty simple to use zero? and mod? directly there.</p> Approval Test Global Rank Patch Code and Test Waiting On stuart.sierra