<?xml version="1.0" encoding="iso-8859-1"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"> <head> <meta http-equiv="content-type" content="text/html; charset=iso-8859-1" /> <title>Logtalk built-in predicate: extends_protocol/2-3</title> <link rel="stylesheet" href="../../screen.css" type="text/css" media="screen"/> <link rel="stylesheet" href="../../print.css" type="text/css" media="print"/> </head> <body> <div class="top-left">Logtalk reference manual</div> <div class="top-right">Built-in predicate: extends_protocol/2-3</div> <div class="bottom-left"><span class="page"/></div> <div class="bottom-right"><span class="page"/></div> <div class="navtop"><a href="../../index.html">contents</a> > <a href="../index.html">reference manual</a> > <a href="../index.html#builtins">built-in predicates</a></div> <h2 class="code">extends_protocol/2-3</h2> <h4>Description</h4> <pre>extends_protocol(Protocol1, Protocol2) extends_protocol(Protocol1, Protocol2, Scope)</pre> <p> Enumerates, by backtracking, all pairs of protocols such that the first one extends the second. The relation scope is represented by the atoms <code>public</code>, <code>protected</code>, and <code>private</code>. </p> <h4>Template and modes</h4> <pre>extends_protocol(?protocol_identifier, ?protocol_identifier) extends_protocol(?protocol_identifier, ?protocol_identifier, ?scope)</pre> <h4>Errors</h4> <dl class="errors"> <dt>Protocol1 is neither a variable nor a valid protocol identifier:</dt> <dd><code>type_error(protocol_identifier, Protocol1)</code></dd> <dt>Protocol2 is neither a variable nor a valid protocol identifier:</dt> <dd><code>type_error(protocol_identifier, Protocol2)</code></dd> <dt>Scope is neither a variable nor a valid entity scope:</dt> <dd><code>type_error(scope, Scope)</code></dd> </dl> <h4>Examples</h4> <pre>| ?- extends_protocol(listp, Protocol). | ?- extends_protocol(Protocol, termp, private).</pre> <div class="footer"> <div class="navbottom"><a href="extends_object2_3.html">previous</a> | <a href="../../glossary.html">glossary</a> | <a href="implements_protocol2_3.html">next</a></div> <div class="copyright">Copyright © <a href="mailto:pmoura@logtalk.org">Paulo Moura</a> — <a href="http://www.logtalk.org">Logtalk.org</a></div> <div class="footnote"> <span class="validators"><a href="http://validator.w3.org/check/referer">XHTML</a> + <a href="http://jigsaw.w3.org/css-validator/check/referer">CSS</a></span> <span class="date">Last updated on: November 16, 2005</span> </div> </div> </body> </html>