#330 Use annotations to suppress warnings

[Tom Copeland]

i.e., use java.lang.SuppressWarning.

[Tom Copeland]

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First step would be to make current //NOPMD functionality
available via an annotation. But can an annotation apply to
just one line? It can apply to classes, methods, and local
variables...

tom

[Tom Copeland]

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Here's what @SuppressWarnings looks like:

@SuppressWarnings({"rule1","rule2"})

Here's the Javadoc:

http://java.sun.com/j2se/1.5.0/docs/api/java/lang/SuppressWarnings.html

Hm, so it can target any one of {TYPE, FIELD, METHOD,
PARAMETER, CONSTRUCTOR, LOCAL_VARIABLE}. Cool, well, that
should about cover it.

Hm, now how best to integrate it. Intercept the warnings as
they are added, like NOPMD does? Or wait until the end and
postprocess the Report object? Hm.

Tom

[Tom Copeland]

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More data; this code:

@SuppressWarnings({"hi","hey"})
public class Foo {
}

produces this AST:

CompilationUnit
TypeDeclaration
Annotation
SingleMemberAnnotation
Name:SuppressWarnings
MemberValue
MemberValueArrayInitializer
MemberValue
PrimaryExpression
PrimaryPrefix
Literal:"hi"
MemberValue
PrimaryExpression
PrimaryPrefix
Literal:"hey"
ClassOrInterfaceDeclaration(Foo)(class)
ClassOrInterfaceBody

[Tom Copeland]

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OK, this is started, you can now suppress warnings for an
entire class like this:

@SuppressWarnings()
public class Foo {
// lots of code, no PMD reports!
}

And the old way - //NOPMD - still works as well.

Can you give it a whirl and see if you notice any problems?

Thanks,

Tom

[Tom Copeland]

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Oops, I should mention, there's an updated pmd-3.3.jar file
here:

http://infoether/com/~tom/pmd-3.3.jar

that contains this feature.

tom

[Tom Copeland]

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Ack, make that:

http://infoether.com/~tom/pmd-3.3.jar

Tom

[Wim Deblauwe]

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Very nice feature Tom! But to avoid missing things you want
to see, you should really specify the exact rules that
should be ignored. Currently NOPMD is just too broad. You
can have a perfectly good reason for putting NOPMD for 1
rule, but later another rule can be violated in that piece
of code, and you will not have noticed it.

keep up the good work!

[Tom Copeland]

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you should really specify the exact rules
that should be ignored

Definitely, right on, I agree. We want more granularity,
like this:

@SuppressWarnings({"rule1","rule2"})

We'll keep this RFE open until that's implemented...

Yours,

Tom

[Wim Deblauwe]

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I was about to write "don't forget to define constants/enum
for those rules to avoid typo's" but that would lead to
PMD-specific imports in your code and I'm not sure that is
appropriate. Maybe something to be discussed.

[Tom Copeland]

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Yup, some folks have suggested variations on that here:

http://www.javalobby.org/java/forums/t49508.html

I'm thinking something like "pmd.UnusedMethod" might be the
way to go for now...

Yours,

Tom

[Tom Copeland]

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Now the XML report for suppressions looks like this:
$ ./pmd.sh Foo.java xml unusedcode -targetjdk 1.5

<pmd version="3.3" timestamp="2005-10-06T09:47:50.090" elapsedtime="0s">
<suppressedviolation filename="/home/tom/pmd/pmd/bin/Foo.java" suppressiontype="annotation" msg="Avoid unused local variables such as 'x'">
</suppressedviolation></pmd>

So it contains the method of suppression...

tom

[Tom Copeland]

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Implemented in CVS, and you can download a new pmd-3.3.jar
file here:

http://infoether.com/~tom/pmd-3.3.jar

that contains this feature. Thanks to everyone for the
feedback... bug reports, comments, questions welcome!

Yours,

Tom