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| <title>Chapter 4. Idioms</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 Programming Guide"><link rel="up" href="index.html" title="The AspectJTM Programming Guide"><link rel="previous" href="examples-reusable.html" title="Reusable Aspects"><link rel="next" href="pitfalls.html" title="Chapter 5. Pitfalls"></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">Chapter 4. Idioms</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="examples-reusable.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="pitfalls.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><h2 class="title"><a name="idioms"></a>Chapter 4. Idioms</h2></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><a href="idioms.html#idioms-intro">Introduction</a></dt></dl></div><div class="sect1"><a name="idioms-intro"></a><div class="titlepage"><div><h2 class="title" style="clear: both"><a name="idioms-intro"></a>Introduction</h2></div></div><p> |
| This chapter consists of very short snippets of AspectJ code, |
| typically pointcuts, that are particularly evocative or useful. |
| This section is a work in progress. |
| </p><p> |
| Here's an example of how to enfore a rule that code in the |
| java.sql package can only be used from one particular package in |
| your system. This doesn't require any access to code in the |
| java.sql package. |
| </p><pre class="programlisting"> |
| /* Any call to methods or constructors in java.sql */ |
| pointcut restrictedCall(): |
| call(* java.sql.*.*(..)) || call(java.sql.*.new(..)); |
| |
| /* Any code in my system not in the sqlAccess package */ |
| pointcut illegalSource(): |
| within(com.foo..*) && !within(com.foo.sqlAccess.*); |
| |
| declare error: restrictedCall() && illegalSource(): |
| "java.sql package can only be accessed from com.foo.sqlAccess"; |
| </pre><p>Any call to an instance of a subtype of AbstractFacade whose class is |
| not exactly equal to AbstractFacade:</p><pre class="programlisting"> |
| pointcut nonAbstract(AbstractFacade af): |
| call(* *(..)) |
| && target(af) |
| && !if(af.getClass() == AbstractFacade.class); |
| </pre><p> If AbstractFacade is an abstract class or an interface, then every |
| instance must be of a subtype and you can replace this with: </p><pre class="programlisting"> |
| pointcut nonAbstract(AbstractFacade af): |
| call(* *(..)) |
| && target(af); |
| </pre><p> Any call to a method which is defined by a subtype of |
| AbstractFacade, but which isn't defined by the type AbstractFacade itself: |
| </p><pre class="programlisting"> |
| pointcut callToUndefinedMethod(): |
| call(* AbstractFacade+.*(..)) |
| && !call(* AbstractFacade.*(..)); |
| </pre><p> The execution of a method that is defined in the source code for a |
| type that is a subtype of AbstractFacade but not in AbstractFacade itself: |
| </p><pre class="programlisting"> |
| pointcut executionOfUndefinedMethod(): |
| execution(* *(..)) |
| && within(AbstractFacade+) |
| && !within(AbstractFacade) |
| </pre></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="examples-reusable.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="pitfalls.html">Next</a></td></tr><tr><td width="40%" align="left">Reusable Aspects </td><td width="20%" align="center"><a accesskey="u" href="index.html">Up</a></td><td width="40%" align="right"> Chapter 5. Pitfalls</td></tr></table></div></body></html> |
