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| <td class="back"><a id="top"></a><a href="s4.2.a.html" rel="prev"><< §4.2.(a) Method composition</a></td> |
| <td class="top"><a href="index.html" rel="contents">↑ Table of Contents ↑</a></td> |
| <td class="next"><a href="s4.2.c.html" rel="next">§4.2.(c) Replacing composition >></a></td> |
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| <div class="breadcrumb"><a class="nav" href="s4.html" rel="section">§4 Callin Binding</a> > <a class="nav" href="s4.2.html" rel="section">§4.2 Callin modifiers (before, after, replace)</a></div> |
| <div class="subsect depth3" id="s4.2.b"> |
| <h4 class="subsect">§4.2.(b) <span class="title">Additive composition</span><a class="img" href="s4.2.b.html" |
| title="PermaLink to (b) Additive composition"><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
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| <p>The <code>before</code> and <code>after</code> modifiers have the |
| effect of adding a call to the role method at the beginning or end |
| of the base method, resp.<br /> |
| In this case no data are transferred from the role to the base, |
| so if the role method has a result, this will always be ignored. |
| |
| </p> |
| <h5 class="listing">Example code (Callin):</h5> |
| <div class="listing example frame"> |
| <table class="listing"> |
| <tr class="line odd"> |
| <td class="ln">1</td> |
| <td><pre><b>team</b> <b>class</b> Company {</pre></td> |
| </tr> |
| <tr class="line even"> |
| <td class="ln">2</td> |
| <td><pre> <b>protected</b> <b>class</b> Employee <b>playedBy</b> Person {</pre></td> |
| </tr> |
| <tr class="line odd"> |
| <td class="ln">3</td> |
| <td><pre> <b>public</b> <b>void</b> recalculateIncome() { ... }</pre></td> |
| </tr> |
| <tr class="line even"> |
| <td class="ln">4</td> |
| <td><pre> recalculateIncome <em><b><-</b> after</em> haveBirthday; <span class="comment">// callin binding</span></pre></td> |
| </tr> |
| <tr class="line odd"> |
| <td class="ln">5</td> |
| <td><pre> }</pre></td> |
| </tr> |
| <tr class="line even"> |
| <td class="ln">6</td> |
| <td><pre>}</pre></td> |
| </tr> |
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| <div class="codecomment"> |
| <p>Line 4 declares a callin binding for the role method <code>recalculateIncome()</code> |
| defined in line 3. In combination with the role binding in line 2 this has the following effect: |
| |
| </p> |
| <ul> |
| <li><strong>After</strong> every call of the method <code>Person.haveBirthday</code> |
| the method <code>Company.recalculateIncome</code> is called. |
| </li> |
| </ul> |
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| <td class="back"><a href="s4.2.a.html" rel="prev"><< §4.2.(a) Method composition</a></td> |
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| <td class="next"><a href="s4.2.c.html" rel="next">§4.2.(c) Replacing composition >></a></td> |
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| <div class="breadcrumb"><a class="nav" href="s4.html" rel="section">§4 Callin Binding</a> > <a class="nav" href="s4.2.html" rel="section">§4.2 Callin modifiers (before, after, replace)</a></div> |
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| width="88" /></a><address>© Stephan Herrmann, Christine Hundt, Marco Mosconi</address> |
| OT/J version 1.3 — last modified: 2011-05-12 |
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