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<h1 xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0"> | |
OclVoid | |
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<h2 class="title" style="clear: both"> | |
<a name="OclVoid"></a> | |
<span class="bold"><strong> | |
<code class="code">OclVoid</code> | |
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<p>The type OclVoid is a type that conforms to all other types except OclInvalid. | |
It has one single instance, identified as | |
<code class="code">null</code>, that corresponds with the UML LiteralNull value specification. | |
Any property call applied on | |
<code class="code">null</code> results in | |
<code class="code">invalid</code>, except for the | |
oclIsUndefined(), oclIsInvalid(), =(OclAny) and <>(OclAny) operations. | |
However, by virtue of the implicit conversion to a collection literal, | |
an expression evaluating to | |
<code class="code">null</code> can be used as source of collection operations (such as ‘isEmpty’). | |
If the source is the | |
<code class="code">null</code> literal, it is implicitly converted to Bag{}. | |
</p> | |
<p>OclVoid is itself an instance of the metatype VoidType.</p> | |
<p>conformsTo | |
<a class="link" href="OclAny.html" title="OclAny"> | |
<code class="code">OclAny</code> | |
</a> | |
</p> | |
<p> | |
<span class="bold"><strong>Operations</strong></span> | |
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<p> | |
<code class="code">=(object2 : OclSelf[?]) : Boolean[1]</code> | |
precedence: | |
<code class="code">EQUALITY</code> | |
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<p>Redefines the OclAny operation, returning | |
<code class="code">true</code> if object is | |
<code class="code">null</code>, | |
<code class="code">invalid</code> | |
if object is | |
<code class="code">invalid</code>, | |
<code class="code">false</code> otherwise. | |
</p> | |
<p> | |
<code class="code"><>(object2 : OclSelf[?]) : Boolean[1]</code> | |
precedence: | |
<code class="code">EQUALITY</code> | |
</p> | |
<p> | |
<code class="code">allInstances() : Set(OclSelf[*|?])</code> | |
</p> | |
<p>Returns | |
<code class="code">Set{null}</code>. | |
</p> | |
<p> | |
<code class="code">and(b : Boolean[?]) : Boolean[?]</code> | |
precedence: | |
<code class="code">AND</code> | |
</p> | |
<p> | |
<code class="code">implies(b : Boolean[?]) : Boolean[?]</code> | |
precedence: | |
<code class="code">IMPLIES</code> | |
</p> | |
<p> | |
<code class="code">oclAsSet() : Set(OclSelf)</code> | |
</p> | |
<p> | |
<code class="code">oclIsInvalid() : Boolean[1] validating</code> | |
</p> | |
<p> | |
<code class="code">oclIsUndefined() : Boolean[1] validating</code> | |
</p> | |
<p> | |
<code class="code">or(b : Boolean[?]) : Boolean[?]</code> | |
precedence: | |
<code class="code">OR</code> | |
</p> | |
<p> | |
<code class="code">toString() : String[1]</code> | |
</p> | |
<p>Returns | |
<code class="code">null</code>. | |
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