yap-6.3/Logtalk/manuals/refman/methods/retract1.html

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<h2><code><a class="back" title="Return to index" href="../index.html#retract1">retract/1</a></code></h2>
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<h4>Description</h4>

<blockquote>
<pre>
retract(Clause)
retract((Head:-Body))
</pre>
<p>
	Retracts a dynamic clause from an object. Note however that if the clauses for the dynamic predicate are contained in a category the predicate will fail.
</p>
</blockquote>

<h4>Template and modes</h4>

<blockquote>
<pre>
retract(+clause)
</pre>
</blockquote>

<h4>Errors</h4>

<blockquote>
	<dl>
		<dt>Head is a variable:</dt>
			<dd><code>instantiation_error</code></dd>
		<dt>Head is neither a variable nor a callable term:</dt>
			<dd><code>type_error(callable, Head)</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>
		<dt>The predicate indicator of Head is not declared:</dt>
			<dd><code>existence_error(predicate_declaration, Head)</code></dd>
	</dl>
</blockquote>

<h4>Examples</h4>

<blockquote>
	<dl>
		<dt>To retract a matching clause of any dynamic predicate in <a class="glossary" title="Go to glossary definition" href="../../glossary.html#this">this</a>:</dt>
			<dd><code>retract(Clause)</code></dd>
		<dt>To retract a matching clause of a public or protected dynamic predicate in <a class="glossary" title="Go to glossary definition" href="../../glossary.html#self">self</a>:</dt>
			<dd><code>::retract(Clause)</code></dd>
		<dt>To retract a matching clause of a public dynamic predicate in an object:</dt>
			<dd><code>Object::retract(Clause)</code></dd>
	</dl>
</blockquote>

<hr />
<p class="center">
<strong><a href="clause2.html">Previous</a> | <a href="retractall1.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
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Logtalk files git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@55 b08c6af1-5177-4d33-ba66-4b1c6b8b522a 2001-06-06 21:07:01 +01:00			`<!doctype html public "-//W3C//DTD HTML 4.01//EN"`
			`"http://www.w3.org/TR/html4/strict.dtd">`

			`<html>`

			`<head>`
			`<title>retract/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#retract1">retract/1</a></code></h2>`
			`<hr />`

			`<h4>Description</h4>`

			`<blockquote>`
			`<pre>`
			`retract(Clause)`
			`retract((Head:-Body))`
			`</pre>`
			`<p>`
			`Retracts a dynamic clause from an object. Note however that if the clauses for the dynamic predicate are contained in a category the predicate will fail.`
			`</p>`
			`</blockquote>`

			`<h4>Template and modes</h4>`

			`<blockquote>`
			`<pre>`
			`retract(+clause)`
			`</pre>`
			`</blockquote>`

Updated to Logtalk 2.9.1 git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@211 b08c6af1-5177-4d33-ba66-4b1c6b8b522a 2001-12-05 23:57:48 +00:00			`<h4>Errors</h4>`
Logtalk files git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@55 b08c6af1-5177-4d33-ba66-4b1c6b8b522a 2001-06-06 21:07:01 +01:00
			`<blockquote>`
			`<dl>`
			`<dt>Head is a variable:</dt>`
			`<dd><code>instantiation_error</code></dd>`
			`<dt>Head is neither a variable nor a callable term:</dt>`
			`<dd><code>type_error(callable, Head)</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>`
			`<dt>The predicate indicator of Head is not declared:</dt>`
			`<dd><code>existence_error(predicate_declaration, Head)</code></dd>`
			`</dl>`
			`</blockquote>`

			`<h4>Examples</h4>`

			`<blockquote>`
			`<dl>`
			`<dt>To retract a matching clause of any dynamic predicate in <a class="glossary" title="Go to glossary definition" href="../../glossary.html#this">this</a>:</dt>`
			`<dd><code>retract(Clause)</code></dd>`
			`<dt>To retract a matching clause of a public or protected dynamic predicate in <a class="glossary" title="Go to glossary definition" href="../../glossary.html#self">self</a>:</dt>`
			`<dd><code>::retract(Clause)</code></dd>`
			`<dt>To retract a matching clause of a public dynamic predicate in an object:</dt>`
			`<dd><code>Object::retract(Clause)</code></dd>`
			`</dl>`
			`</blockquote>`

			`<hr />`
			`<p class="center">`
			`<strong><a href="clause2.html">Previous</a> \| <a href="retractall1.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">`
Updated to Logtalk 2.9.1 git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@211 b08c6af1-5177-4d33-ba66-4b1c6b8b522a 2001-12-05 23:57:48 +00:00			`Last updated on: October 21, 2001`
Logtalk files git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@55 b08c6af1-5177-4d33-ba66-4b1c6b8b522a 2001-06-06 21:07:01 +01:00			`</p>`
			`<hr />`

			`</body>`

			`</html>`