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| <title>Covariant methods and Join Point matching</title><link rel="stylesheet" href="aspectj-docs.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.44"><link rel="home" href="index.html" title="The AspectJTM 5 Development Kit Developer's Notebook"><link rel="up" href="covariance.html" title="Chapter 5. Covariance"><link rel="previous" href="covariance.html" title="Chapter 5. Covariance"><link rel="next" href="varargs.html" title="Chapter 6. Varargs"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Covariant methods and Join Point matching</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="covariance.html">Prev</a> </td><th width="60%" align="center">Chapter 5. Covariance</th><td width="20%" align="right"> <a accesskey="n" href="varargs.html">Next</a></td></tr></table><hr></div><div class="sect1"><a name="covariance-and-join-point-matching"></a><div class="titlepage"><div><h2 class="title" style="clear: both"><a name="covariance-and-join-point-matching"></a>Covariant methods and Join Point matching</h2></div></div><p>The join point matching rules for <tt>call</tt> | |
| and <tt>execution</tt> pointcut designators are extended | |
| to match against covariant methods.</p><p> | |
| Given the classes <tt>A</tt> and <tt>B</tt> | |
| as defined in the previous section, and the program fragment | |
| </p><pre class="programlisting"> | |
| A a = new A(); | |
| B b = new B(); | |
| a.whoAreYou(); | |
| b.whoAreYou(); | |
| </pre><p>The signatures for the call join point <tt>a.whoAreYou()</tt> are | |
| simply:</p><pre class="programlisting"> | |
| A A.whoAreYou() | |
| </pre><p>The signatures for the call join point <tt>b.whoAreYou()</tt> are: | |
| </p><pre class="programlisting"> | |
| A A.whoAreYou() | |
| B B.whoAreYou() | |
| </pre><p>Following the join point matching rules given in <a href="jpsigs.html">Join Point Signatures</a>,</p><div class="variablelist"><dl><dt><a name="d0e3197"></a><span class="term">call(* whoAreYou())</span></dt><dd><p><a name="d0e3200"></a>Matches both calls, (since each call join point has at least | |
| one matching signature). | |
| </p></dd><dt><a name="d0e3203"></a><span class="term">call(* A.whoAreYou())</span></dt><dd><p><a name="d0e3206"></a>Matches both calls, (since each call join point has at least | |
| one matching signature). | |
| </p></dd><dt><a name="d0e3209"></a><span class="term">call(A whoAreYou())</span></dt><dd><p><a name="d0e3212"></a>Matches both calls, (since each call join point has at least | |
| one matching signature). | |
| </p></dd><dt><a name="d0e3215"></a><span class="term">call(A B.whoAreYou())</span></dt><dd><p><a name="d0e3218"></a>Does not match anything - neither of the call join points | |
| has a signature matched by this pattern. A lint warning is | |
| given for the call <tt>a.whoAreYou()</tt> ("does not match | |
| because declaring type is A, if match required use target(B)"). | |
| </p></dd><dt><a name="d0e3224"></a><span class="term">call(A+ B.whoAreYou())</span></dt><dd><p><a name="d0e3227"></a>Matches the call to <tt>b.whoAreYou()</tt> since | |
| the signature pattern matches the signature <tt>B B.whoAreYou()</tt>. | |
| A lint warning is given for the call <tt>a.whoAreYou()</tt> ("does not match | |
| because declaring type is A, if match required use target(B)"). | |
| </p></dd><dt><a name="d0e3239"></a><span class="term">call(B A.whoAreYou())</span></dt><dd><p><a name="d0e3242"></a>Does not match anything since neither join point has a | |
| signature matched by this pattern. | |
| </p></dd><dt><a name="d0e3245"></a><span class="term">call(B whoAreYou())</span></dt><dd><p><a name="d0e3248"></a>Matches the call to <tt>b.whoAreYou()</tt> only. | |
| </p></dd><dt><a name="d0e3254"></a><span class="term">call(B B.whoAreYou())</span></dt><dd><p><a name="d0e3257"></a>Matches the call to <tt>b.whoAreYou()</tt> only. | |
| </p></dd></dl></div><p>The rule for signature matching at call and execution join points | |
| is unchanged from AspectJ 1.2: a call or execution pointcut matches if | |
| the signature pattern matches at least one of the signatures of the | |
| join point, and if the modifiers of the method or constructor are matched | |
| by any modifier pattern or annotation pattern that may be present.</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="covariance.html">Prev</a> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right"> <a accesskey="n" href="varargs.html">Next</a></td></tr><tr><td width="40%" align="left">Chapter 5. Covariance </td><td width="20%" align="center"><a accesskey="u" href="covariance.html">Up</a></td><td width="40%" align="right"> Chapter 6. Varargs</td></tr></table></div></body></html> |