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| <td class="back"><a id="top"></a><a href="s1.3.1.html" rel="prev"><< §1.3.1 Acquisition and implicit inheritance of role classes</a></td> |
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| <div class="breadcrumb"><a class="nav" href="s1.html" rel="section">§1 Teams and Roles</a> > <a class="nav" href="s1.3.html" rel="section">§1.3 Acquisition and implicit inheritance of role classes</a></div> |
| <div class="sect depth3" id="s1.3.2"> |
| <h3 class="sect">§1.3.2 Regular role inheritance<a class="img" href="s1.3.2.html" |
| title="PermaLink to §1.3.2 Regular role inheritance"><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
| alt="" /></a></h3> |
| <p>In addition to implicit inheritance, roles may also inherit using |
| the standard Java keyword <code>extends</code>. These restrictions apply: |
| |
| </p> |
| <div class="subsect depth4" id="s1.3.2.a"> |
| <h4 class="subsect">(a) <span class="title">Super-class restrictions</span><a class="img" href="s1.3.2.a.html" |
| title="PermaLink to (a) Super-class restrictions"><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
| alt="" /></a></h4> |
| <p>If the super-class of a role is again a role it must be a direct role of |
| an enclosing team |
| This rule is simply enforced by disallowing type anchors in the |
| <code>extends</code> clause |
| (see <a href="s1.2.2.g.html" title="§1.2.2.(g) Legal contexts" |
| class="sect">§1.2.2.(g)</a>). |
| As an effect, the super-class may never be more deeply nested than the sub-class. |
| |
| </p> |
| </div> |
| <div class="subsect depth4" id="s1.3.2.b"> |
| <h4 class="subsect">(b) <span class="title">Inheriting and overriding the extends clause</span><a class="img" href="s1.3.2.b.html" |
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| <p>If a role overrides another role by implicit inheritance, it may |
| change the inherited <code>extends</code> clause |
| (see <a href="s1.3.1.g.html" |
| title="§1.3.1.(g) Implicitly inheriting super-types" |
| class="sect">§1.3.1.(g)</a> above) only if the new super-class |
| is a sub-class of the class in the overridden extends clause. |
| I.e., an implicit sub-role may <em>specialize</em> the extends clause of its |
| implicit super-role. |
| |
| </p> |
| </div> |
| <div class="subsect depth4" id="s1.3.2.c"> |
| <h4 class="subsect">(c) <span class="title">Constructors and overridden 'extends' </span><a class="img" href="s1.3.2.c.html" |
| title="PermaLink to (c) Constructors and overridden 'extends' "><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
| alt="" /></a></h4> |
| <p>Each constructor of a role class that overrides the extends clause of its |
| implicit super-role must invoke a constructor of this newly introduced |
| explicit super-class. Thus it may not use a <code>tsuper</code> constructor |
| (see <a href="s2.4.2.html" |
| title="§2.4.2 Role creation via a regular constructor" |
| class="sect">§2.4.2</a>). |
| |
| </p> |
| </div> |
| <div class="subsect depth4" id="s1.3.2.d"> |
| <h4 class="subsect">(d) <span class="title">Adding implemented interfaces</span><a class="img" href="s1.3.2.d.html" |
| title="PermaLink to (d) Adding implemented interfaces"><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
| alt="" /></a></h4> |
| <p><code>implements</code> declarations are additive, i.e., an implicit |
| sub-role may add more interfaces but has to implement all interfaces of |
| its implicit super-role, too. |
| |
| </p> |
| </div> |
| <div class="subsect depth4" id="s1.3.2.e"> |
| <h4 class="subsect">(e) <span class="title">Visibility of inherited methods</span><a class="img" href="s1.3.2.e.html" |
| title="PermaLink to (e) Visibility of inherited methods"><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
| alt="" /></a></h4> |
| <p> |
| When a role inherits non-public methods from a regular class (as its super class), |
| these methods are considered as private for the role, i.e., they can only be |
| accessed in an unqualified method call <code>m()</code> using the implicit receiver <code>this</code>. |
| |
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| <td class="back"><a href="s1.3.1.html" rel="prev"><< §1.3.1 Acquisition and implicit inheritance of role classes</a></td> |
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| <div class="breadcrumb"><a class="nav" href="s1.html" rel="section">§1 Teams and Roles</a> > <a class="nav" href="s1.3.html" rel="section">§1.3 Acquisition and implicit inheritance of role classes</a></div> |
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