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git-svn-id: https://pmd.svn.sourceforge.net/svnroot/pmd/trunk@530 51baf565-9d33-0410-a72c-fc3788e3496d
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Tom Copeland
2002-07-26 18:46:36 +00:00
parent 81316fbcf5
commit 665ca61ba3
1 changed files with 51 additions and 2 deletions
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53
pmd/xdocs/howtowritearule.xml
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@ -88,7 +88,8 @@ CompilationUnit
You can generate this yourself by:
<ul>
<li>Put the example file in the pmd/test-data directory in a file called "Example.java"</li>
<li>Edit the class <code>net.sourceforge.pmd.PMD</code> and uncomment the line that says <code>c.dump();</code></li>
<li>Edit the class <code>net.sourceforge.pmd.PMD</code> and uncomment the line that
says <code>c.dump();</code> and the line that says <code>t.printStackTrace();</code></li>
<li>Open a command prompt and cd into the pmd/etc directory</li>
<li>Recompile the project using the Ant task; i.e., <code>ant compile</code></li>
<li>Run the <code>go</code> batch file to run PMD on one file, like this: <code>go Example xml rulesets/basic.xml</code>. The go.bat file
@ -198,14 +199,62 @@ which should either be acted on or reported.
<li>example - A little code snippet in CDATA tags that shows a rule violation</li>
</ul>
</subsection>
<p>
We'll just leave this rule in the rulesets/basic.xml ruleset for now. If you write rules for your own
project that aren't applicable to other projects (rules to catch Thread creation, for example, or rules to catch
System.out.println() usages) you might want to make a new ruleset <code>myproject.xml</code> and put your rules in there.
</p>
<subsection name="Run PMD using your new ruleset">
<p>
Remember when we ran go.bat over the Example.java file? Do it again. This time your "hello world" will show up right after the
AST gets printed out. If it doesn't, post a message to the
forum - http://sourceforge.net/forum/forum.php?forum_id=188192 - so we can improve this document :-)
</p>
</subsection>
<subsection name="Write code to add rule violations where appropriate">
<p>
Now that we've identified our problem, recognized the AST pattern that illustrates the problem, written a new rule, and plugged
it into a ruleset, we need to actually make our rule find the problem. Like this:
</p>
<source>
<![CDATA[
public class WhileLoopsMustUseBracesRule extends AbstractRule {
public Object visit(ASTWhileStatement node, Object data) {
SimpleNode firstStmt = (SimpleNode)node.jjtGetChild(1);
if (!hasBlockAsFirstChild(firstStmt)) {
RuleContext ctx = (RuleContext)data;
ctx.getReport().addRuleViolation(createRuleViolation(ctx, node.getBeginLine()));
}
return super.visit(node,data);
}
private boolean hasBlockAsFirstChild(SimpleNode node) {
return (node.jjtGetNumChildren() != 0 && (node.jjtGetChild(0) instanceof ASTBlock));
}
}
]]>
</source>
</subsection>
<p>
TODO - if you don't understand the code for the rule, post a message to the
forum - http://sourceforge.net/forum/forum.php?forum_id=188192 - so we can improve this document :-)
</p>
<subsection name="Repeat as necessary">
<p>
I've found that my rules usually don't work the first time, and so I have to go back and tweak them a
couple times. That's OK, if we were perfect programmers PMD would be useless anyhow :-).
</p>
<p>As an acceptance test of sorts, I usually run a rule on the JDK 1.4 source code and make sure that a random
sampling of the problems found are in fact legitimate rule violations.
This also ensures that the rule doesn't get confused by nested
inner classes or any of the other oddities that appear at various points in the JDK source.
</p>
<p>
You're rolling now. If you think a rule would benefit the Java development community as a whole,
post a message to the forum - http://sourceforge.net/forum/forum.php?forum_id=188192 - so we can get the rule
moved into one of the core rulesets. Thanks!
</p>
</subsection>
</section>
</body>