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yap-6.3/Logtalk/manuals/refman/methods/asserta1.html
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<title>asserta/1</title>
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<h2><code><a class="back" title="Return to index" href="../index.html#asserta1">asserta/1</a></code></h2>
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<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: August 6, 2002
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