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<title>Logtalk built-in method: assertz/1</title>
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<div class="top-left">Logtalk reference manual</div>
<div class="top-right">Built-in method: assertz/1</div>
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<h2 id="methods_assertz1" class="codenp">assertz/1</h2>
<h4>Description</h4>
<pre>assertz(Head)
assertz((Head:-Body))</pre>
<p>
Asserts a clause as the last 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>
<h4>Template and modes</h4>
<pre>assertz(+clause)</pre>
<h4>Errors</h4>
<dl>
<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>
<h4>Examples</h4>
<dl>
<dt>To assert a clause as the last one for any dynamic predicate in <a class="glossary" title="Go to glossary definition" href="../../glossary.html#this">this</a>:</dt>
<dd><code>assertz(Clause)</code></dd>
<dt>To assert a clause as the last 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>::assertz(Clause)</code></dd>
<dt>To assert a clause as the last one for any public dynamic predicate in an object:</dt>
<dd><code>Object::assertz(Clause)</code></dd>
</dl>
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<span>Copyright © <a href="mailto:pmoura@logtalk.org">Paulo Moura</a> — <a href="http://logtalk.org">Logtalk.org</a></span><br/>
<span>Last updated on: October 26, 2006</span>
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