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| <td class="back"><a id="top"></a><a href="s4.2.c.html" rel="prev"><< §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.d"> |
| <h4 class="subsect">§4.2.(d) <span class="title">Callin methods</span><a class="img" href="s4.2.d.html" title="PermaLink to (d) Callin methods"><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
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| <p>Role methods to be bound by a callin replacement binding must have |
| the modifier <code>callin</code>. This modifier is only allowed for methods |
| of a role class.<br /> |
| A method with the <code>callin</code> modifier can only be called |
| |
| </p> |
| <ul> |
| <li>via a callin replace binding</li> |
| <li>by a <code>super</code> or <code>tsuper</code> call from an overriding callin method. |
| </li> |
| </ul> |
| <p>It is illegal for a <code>callin</code> method |
| </p> |
| <ul> |
| <li>to be called directly,</li> |
| <li>to be bound using a callout binding, and</li> |
| <li>to be bound to a base method using a <code>before</code> or <code>after</code> callin binding. |
| </li> |
| </ul> |
| <p>Despite these rules a second level role — which is played by the current role — |
| can intercept the execution of a callin method using any form of callin binding.</p> |
| <p>A callin method cannot override a regular method and vice versa, however, |
| overriding one callin method with another callin method is legal and |
| dynamic binding applies to callin method just like regular methods. |
| <br /> |
| A callin method must not declare its visibility using any of the modifiers <code>public</code>, |
| <code>protected</code> or <code>private</code>. Since callin methods can only be invoked via callin bindings |
| such visibility control would not be useful. |
| |
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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: 2010-05-18 |
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