http://dev.clojure.org/jira This file is an XML representation of an issue en-us 4.4 649 25-07-2011 http://dev.clojure.org/jira/browse/CLJ-932 Clojure <p>The <tt>contains?</tt> function, given a collection which is not an associative (Map, Set, String, array), returns false instead of throwing an exception.</p> <p>This is a subject of confusion when people call <tt>contains?</tt> on sequential collections like lists, and on associative collections which do not implement the <tt>Associative</tt> interface.</p> <p>Other predicates, such as <tt>even?</tt>, throw an exception when passed arguments of an invalid type.</p> CLJ-932

contains? should throw exception on non-keyed collections

Enhancement Minor Closed Completed Stuart Sierra Stuart Sierra Fri, 17 Feb 2012 15:19:20 -0600 Sat, 18 Aug 2012 07:50:41 -0500 Sat, 18 Aug 2012 07:50:41 -0500 Release 1.5 1 2 <p>Patch adds fix, adds some tests, and removes tests reflecting the old behavior.</p> <p>This seems to be working properly, but what about vectors?</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>(contains? [1 2 3] 3) ;-&gt; false </pre> </div></div> <p>The doc string for contains? covers the vector and Java array case explicitly. I'm not saying that this behavior shouldn't change, but at least it is well documented what it currently does in these cases.</p> <p>Agreed. I just want to make sure that we are still ok with this functionality given that things are changing. Are there others (Stuart) that want to chime in here and make the intentions clear? If this is good then I would consider this screened and ready.</p> <p>Vector is Associative, so supporting <tt>contains?</tt> is valid even if it does not do what people might expect:</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java">user=&gt; (contains? [:a :b :c] 2) <span class="code-keyword">true</span> user=&gt; (contains? [:a :b :c] 7) <span class="code-keyword">false</span></pre> </div></div> <p>All I'm trying to change here is have <tt>contains?</tt> throw an exception if the argument is <b>not</b> Associative. The current behavior (returning false) was hiding a bug in my code.</p> <p>I do not consider this a breaking change. I believe the docstring of <tt>contains?</tt> leaves room for this interpretation, but Rich will have the final say.</p> <p>Perfect. I just wanted to make sure that this was intended.</p> Approval Ok Global Rank Patch Code and Test