From: dgregor_at_[hidden]
Date: 2008-05-29 16:34:36
Author: dgregor
Date: 2008-05-29 16:34:35 EDT (Thu, 29 May 2008)
New Revision: 45921
URL: http://svn.boost.org/trac/boost/changeset/45921
Log:
Heterogeneous, proxy-capable Swappable issue
Added:
sandbox/committee/concepts/issues/issues/issue35.xml (contents, props changed)
Added: sandbox/committee/concepts/issues/issues/issue35.xml
==============================================================================
--- (empty file)
+++ sandbox/committee/concepts/issues/issues/issue35.xml 2008-05-29 16:34:35 EDT (Thu, 29 May 2008)
@@ -0,0 +1,42 @@
+<?xml version='1.0' encoding='iso-8859-1' standalone='no'?>
+<!DOCTYPE issue SYSTEM "lwg-issue.dtd" [
+ <!ENTITY nbsp " ">
+] >
+
+<issue num="35" status="Open">
+ <title><code>Swappable</code> should be usable with proxy iterator references</title>
+<section><sref ref="[concept.copymove]"/></section>
+<submitter>LWG</submitter>
+<date>29 May 2008</date>
+
+<discussion>
+ <p>The <code>Swappable</code> concept cannot currently be used with
+ proxy iterator references, because they aren't necessarily
+ lvalues. Moreover, its <code>swap</code> can't be applied to values
+ of different types. For example, it couldn't be used for the proxy
+ references coming from two different iterator types in
+ the <code>swap_ranges</code> algorithm.</p>
+</discussion>
+
+<resolution>
+ <p>Modify the definition of <code>Swappable</code> in
+ [concept.copymove] as follows:</p>
+
+ <pre>
+auto concept Swappable<typename T<ins>, typename U = T</ins>> {
+ void swap(T&<ins>&</ins>, <del>T</del><ins>U</ins>&<ins>&</ins>);
+}
+ </pre>
+ <ol start="11">
+ <li><i>Note</i>: describes types for which <del>two</del> values of <del>that</del><ins>those</ins> type<ins>s</ins>
+ can be swapped.</li>
+ </ol>
+
+ <p>The synopsis in [utility.concepts] will need to be updated
+ accordingly:</p>
+
+ <pre>
+auto concept Swappable<typename T<ins>, typename U = T</ins>> <i>see below</i>;
+ </pre>
+</resolution>
+</issue>