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| <td class="back"><a id="top"></a><a href="s6.1.b.html" rel="prev"><< §6.1.(b) Behavioral reflection</a></td> |
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| <div class="breadcrumb"><a class="nav" href="s6.html" rel="section">§6 Object Teams API</a> > <a class="nav" href="s6.1.html" rel="section">§6.1 Reflection</a></div> |
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| <h4 class="subsect">§6.1.(c) <span class="title">Class literals for roles</span><a class="img" href="s6.1.c.html" |
| title="PermaLink to (c) Class literals for roles"><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
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| <p>The Java syntax for so-called class literals, <code>MyClass<strong>.class</strong></code> |
| (see <a href="http://java.sun.com/docs/books/jls/second_edition/html/expressions.doc.html#251530" |
| class="ext">JLS §15.8.2</a>) |
| can be used for role types with slightly changed semantics: Role types are virtual types (<a href="s1.3.1.html" |
| title="§1.3.1 Acquisition and implicit inheritance of role classes" |
| class="sect">§1.3.1</a>) |
| that are bound dynamically (<a href="s1.3.1.e.html" title="§1.3.1.(e) Dynamic binding of types" |
| class="sect">§1.3.1.(e)</a>). This applies to role class literals, too. |
| From this follows the constraint that a role class literal can only be used within the non-static context of a team, |
| ie., for evaluating a role class literal an enclosing team instance must be in scope. |
| <br /> |
| Unlike regular type checking for role types, the class literal itself does not have a dependent type. |
| Thus type checking of calls to methods like <code>hasRole(Object, Class)</code> cannot detect, whether the <code>Class</code> instance |
| has actually been obtained from the correct team instance. Any attempt to pass a class that is not known |
| as a bound role within the given team results in an <code>IllegalArgumentException</code> at run-time. |
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| width="88" /></a><address>© Stephan Herrmann, Christine Hundt, Marco Mosconi</address> |
| OT/J version 1.3 — last modified: 2011-05-15 |
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