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<title>Logtalk control construct: ::/1</title>
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<a href="../../index.html">contents</a> &gt; <a href="../index.html">reference manual</a> &gt; <a href="../index.html#constructs">control constructs</a>
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<h2><code>::/1</code></h2>
<h4>Description</h4>
<blockquote>
<pre>::Predicate
::(Predicate1, Predicate2, ...)
::(Predicate1; Predicate2; ...)</pre>
<p>
Send a message to <a class="glossary" title="Go to glossary definition" href="../../glossary.html#self">self</a>. Only used in the body of a predicate definition. The argument should match a public or protected predicate of <a class="glossary" title="Go to glossary definition" href="../../glossary.html#self">self</a>. It may also match a private predicate if the predicate is imported from a category, if used from inside a category, or when using private inheritance. We can also send a set of messages to self. The "<code>,</code>" and "<code>;</code>" in the list have the usual Prolog meaning.
</p>
</blockquote>
<h4>Template and modes</h4>
<blockquote>
<pre>::+messages</pre>
</blockquote>
<h4>Errors</h4>
<blockquote>
<dl>
<dt>Predicate is a variable:</dt>
<dd><code>instantiation_error</code></dd>
<dt>Predicate is declared private:</dt>
<dd><code>permission_error(access, private_predicate, Predicate)</code></dd>
<dt>Predicate is not declared:</dt>
<dd><code>existence_error(predicate_declaration, Predicate)</code></dd>
</dl>
</blockquote>
<h4>Examples</h4>
<blockquote>
<pre>area(Area) :-
::width(Width),
::height(Height),
Area is Width*Height.</pre>
</blockquote>
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Copyright &copy; <a href="mailto:pmoura@logtalk.org">Paulo Moura</a> &mdash; <a href="http://www.logtalk.org">Logtalk.org</a>
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