<!doctype html public "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>asserta/1</title> <link rel=stylesheet href="../../styles.css" type="text/css"> </head> <body> <hr /> <h2><code><a class="back" title="Return to index" href="../index.html#asserta1">asserta/1</a></code></h2> <hr /> <h4>Description</h4> <blockquote> <pre> asserta(Clause) asserta((Head:-Body)) </pre> <p> Asserts a clause as the first one for an object's dynamic predicate. If the predicate is not already declared, then a dynamic predicate declaration is added to the object. </p> </blockquote> <h4>Template and modes</h4> <blockquote> <pre> asserta(+clause) </pre> </blockquote> <h4>Errors</h4> <blockquote> <dl> <dt>Clause is a variable:</dt> <dd><code>instantiation_error</code></dd> <dt>Head is a variable:</dt> <dd><code>instantiation_error</code></dd> <dt>Head is a neither a variable nor a callable term:</dt> <dd><code>type_error(callable, Head)</code></dd> <dt>Body cannot be converted to a goal:</dt> <dd><code>type_error(callable, Body)</code></dd> <dt>The predicate indicator of Head is that of a private predicate:</dt> <dd><code>permission_error(modify, private_predicate, Head)</code></dd> <dt>The predicate indicator of Head is that of a protected predicate:</dt> <dd><code>permission_error(modify, protected_predicate, Head)</code></dd> <dt>The predicate indicator of Head is that of a static predicate:</dt> <dd><code>permission_error(modify, static_predicate, Head)</code></dd> </dl> </blockquote> <h4>Examples</h4> <blockquote> <dl> <dt>To assert a clause as the first one for any dynamic predicate in <a class="glossary" title="Go to glossary definition" href="../../glossary.html#this">this</a>:</dt> <dd><code>asserta(Clause)</code></dd> <dt>To assert a clause as the first one for any public or protected dynamic predicate in <a class="glossary" title="Go to glossary definition" href="../../glossary.html#self">self</a>:</dt> <dd><code>::asserta(Clause)</code></dd> <dt>To assert a clause as the first one for any public dynamic predicate in an object:</dt> <dd><code>Object::asserta(Clause)</code></dd> </dl> </blockquote> <hr /> <p class="center"> <strong><a href="abolish1.html">Previous</a> | <a href="assertz1.html">Next</a> | <a href="../index.html">Table of Contents</a> | <a href="../../bibliography.html">Bibliography</a> | <a href="../../glossary.html">Glossary</a></strong> </p> <p class="center"> Last updated on: October 21, 2001 </p> <hr /> </body> </html>