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<h2><code><a class="back" title="Return to index" href="../index.html#extends_protocol2_3">extends_protocol/2-3</a></code></h2>
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<h4>Description</h4>

<blockquote>
<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.
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<h4>Template and modes</h4>

<blockquote>
<pre>
extends_protocol(?protocol_identifier, ?protocol_identifier)

extends_protocol(?protocol_identifier, ?protocol_identifier, ?entity_scope)
</pre>
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<h3>Errors</h3>

<blockquote>
	<dl>
		<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(entity_scope, Scope)</code></dd>
	</dl>
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<h4>Examples</h4>

<blockquote>
<pre>
| ?- extends_protocol(listp, Protocol).

| ?- extends_protocol(Protocol, termp, private).
</pre>
</blockquote>

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Last updated on: July 4, 2000
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