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| <td class="back"><a id="top"></a><a href="s2.2.c.html" rel="prev"><< §2.2.(c) Typing</a></td> |
| <td class="top"><a href="index.html" rel="contents">↑ Table of Contents ↑</a></td> |
| <td class="next"><a href="s2.2.e.html" rel="next">§2.2.(e) Lowering of arrays >></a></td> |
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| <div class="breadcrumb"><a class="nav" href="s2.html" rel="section">§2 Role Binding</a> > <a class="nav" href="s2.2.html" rel="section">§2.2 Lowering</a></div> |
| <div class="subsect depth3" id="s2.2.d"> |
| <h4 class="subsect">§2.2.(d) <span class="title">Explicit lowering</span><a class="img" href="s2.2.d.html" |
| title="PermaLink to (d) Explicit lowering"><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
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| <p>If a base type is also the super type of its role, |
| which frequently happens, if a base reference is known only by |
| the type <code>Object</code>, lowering cannot be deduced automatically, |
| since a type could be interpreted both as a role type and a base type. |
| These cases may need <strong>explicit lowering</strong>. |
| For this purpose the role class must declare to implement the interface |
| <strong><code>ILowerable</code></strong> (from <code>org.objectteams.ITeam</code>). |
| This will cause the compiler to generate a method |
| </p> |
| <div class="listing plain"><pre><b>public</b> Object lower()</pre></div> |
| <p>for the given role class. Client code may use this method to |
| explicitly request the base object of a given role object. |
| </p> |
| <div class="listing example frame"> |
| <table class="listing"> |
| <tr class="line odd"> |
| <td class="ln">1</td> |
| <td><pre><b>public</b> <b>team</b> <b>class</b> MyTeamA {</pre></td> |
| </tr> |
| <tr class="line even"> |
| <td class="ln">2</td> |
| <td><pre> <b>public</b> <b>class</b> MyRole <em><b>implements</b> ILowerable</em> <b>playedBy</b> MyBase { ... }</pre></td> |
| </tr> |
| <tr class="line odd"> |
| <td class="ln">3</td> |
| <td><pre> <b>public</b> <b>void</b> doSomething() {</pre></td> |
| </tr> |
| <tr class="line even"> |
| <td class="ln">4</td> |
| <td><pre> MyRole r = <b>new</b> MyRole(<b>new</b> MyBase());</pre></td> |
| </tr> |
| <tr class="line odd"> |
| <td class="ln">5</td> |
| <td><pre> Object oMyRole = r;</pre></td> |
| </tr> |
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| <td class="ln">6</td> |
| <td><pre> Object oMyBase = r.<em>lower()</em>;</pre></td> |
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| <td class="ln">7</td> |
| <td><pre> }</pre></td> |
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| <td class="ln">8</td> |
| <td><pre>}</pre></td> |
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| <div class="breadcrumb"><a class="nav" href="s2.html" rel="section">§2 Role Binding</a> > <a class="nav" href="s2.2.html" rel="section">§2.2 Lowering</a></div> |
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| width="88" /></a><address>© Stephan Herrmann, Christine Hundt, Marco Mosconi</address> |
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