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| <td class="back"><a id="top"></a><a href="s2.7.b.html" rel="prev"><< §2.7.(b) Stacking</a></td> |
| <td class="top"><a href="index.html" rel="contents">↑ Table of Contents ↑</a></td> |
| <td class="next"><a href="s2.7.d.html" rel="next">§2.7.(d) Implicit playedBy specialization >></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="s2.7.html" rel="section">§2.7 Advanced structures</a></div> |
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| <h4 class="subsect">§2.7.(c) <span class="title">Layering</span><a class="img" href="s2.7.c.html" title="PermaLink to (c) Layering"><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
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| <p>If roles of a team <code>Secondary</code> are played by roles of another team <code>Primary</code> |
| (i.e., base classes are roles), the team <code>Secondary</code> defines a <strong>layer</strong> over the team <code>Primary</code>. |
| Such layering requires a final reference <code>anchor</code> from <code>Secondary</code> to an instance of <code>Primary</code>. |
| All playedBy declarations within <code>Secondary</code> specify their base classes anchored to that final link <code>anchor</code>. |
| |
| </p><img src="../images/Layering.png" alt="Team layering example" /><p>Due to the anchored base types, layered teams implicitly support the following guarantee: |
| all base objects of roles of <code>Secondary</code> are contained within the team instance specified by the link <code>anchor</code>. |
| If roles of <code>Secondary</code> contain any callin bindings to non-static base methods, these will be triggered only |
| when a base method is invoked on a base instance contained in the team specified by <code>anchor</code>. |
| <br /> |
| In accordance with <a href="s2.6.a.html" |
| title="§2.6.(a) Externalized roles of a base team" |
| class="sect">§2.6.(a)</a> the anchor in such anchored playedBy declarations |
| could also be the pseudo identifier <code>base</code>, provided that <code>Secondary</code> is a nested team, |
| which has a playedBy binding to <code>Primary</code> as its base class. |
| This situation is part of the second example <a href="s2.7.d.html" |
| title="§2.7.(d) Implicit playedBy specialization" |
| class="sect">below (§2.7.(d))</a> (see <code>T1 playedBy TB1</code>). |
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| <div class="breadcrumb"><a class="nav" href="s2.html" rel="section">§2 Role Binding</a> > <a class="nav" href="s2.7.html" rel="section">§2.7 Advanced structures</a></div> |
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| width="88" /></a><address>© Stephan Herrmann, Christine Hundt, Marco Mosconi</address> |
| OT/J version 1.3 — last modified: 2010-10-05 |
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