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| <td class="back"><a id="top"></a><a href="s9.2.1.html" rel="prev"><< §9.2.1 Parameter substitution</a></td> |
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| <div class="breadcrumb"><a class="nav" href="s9.html" rel="section">§9 Value Dependent Classes</a> > <a class="nav" href="s9.2.html" rel="section">§9.2 Using classes with value parameters</a></div> |
| <div class="sect depth3" id="s9.2.2"> |
| <h3 class="sect">§9.2.2 Type conformance<a class="img" href="s9.2.2.html" |
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| <p>Two value dependent types (anchored types) are considered conform only if the anchors |
| of both types refer to <i>the same object(s)</i>. The compiler must be able to statically |
| analyze this anchor identity. |
| |
| </p> |
| <div class="subsect depth4" id="s9.2.2.a"> |
| <h4 class="subsect">(a) <span class="title">Substitutions for type anchors</span><a class="img" href="s9.2.2.a.html" |
| title="PermaLink to (a) Substitutions for type anchors"><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
| alt="" /></a></h4> |
| <p>Only two substitutions are considered for determining anchor identity: |
| |
| </p> |
| <ol> |
| <li>If a method signature uses <code>this</code> as the anchor of any of its types, |
| type checking an application of this method performs the following substitutions: |
| <br /> |
| A simple <code>this</code> expression is substituted by the actual call target |
| of the method application. |
| <br /> |
| A qualified <code>Outer.this</code> expression is substituted by the corresponding |
| enclosing instance of the call target. |
| </li> |
| <li>Assignments from a <code>final</code> identifier to another <code>final</code> |
| identifier are transitively followed, i.e., if <code>t1, t2</code> are final, |
| after an assignment <code>t1=t2</code> the types <code>C<@t1></code> and |
| <code>C<@t2></code> are considered identical. Otherwise <code>C<@t1></code> |
| and <code>C<@t2></code> are incommensurable. |
| <br /> |
| Attaching an actual parameter to a formal parameter in a method call is also considered |
| as an assignment with respect to this rule. |
| </li> |
| </ol> |
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| <div class="subsect depth4" id="s9.2.2.b"> |
| <h4 class="subsect">(b) <span class="title">Conformance of raw types</span><a class="img" href="s9.2.2.b.html" |
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| <p>After anchors have been proven identical, the raw types are checked for compatibility |
| using the standard Java rules. |
| |
| </p> |
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| <td class="back"><a href="s9.2.1.html" rel="prev"><< §9.2.1 Parameter substitution</a></td> |
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| <div class="breadcrumb"><a class="nav" href="s9.html" rel="section">§9 Value Dependent Classes</a> > <a class="nav" href="s9.2.html" rel="section">§9.2 Using classes with value parameters</a></div> |
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