Without getting too far into the code myself, you seem to make some
very good arguments about possible problems in this code. ;-)

I have no idea if this PluginParameterExpressionEvaluator class (and
the referenced code in Plexus) have proper unit tests etc, but it
seems like you could make a great contribution in this area if you
were interested.

Thanks for the comments -- keep it up!

Wayne

On 2/13/07, Jiaqi Guo <[EMAIL PROTECTED]> wrote:
Hi Franz,

I tried to get PluginDescriptor within a mojo and got
PluginParameterException, then I started looking at this code.

Assume expression is string "plugin", pathSeparator is -1, the
expression.substring(1) becomes "lugin". Did I miss anything here?

And then looking at ReflectionValueExtractor.java today, I just realized
ReflectionValueExtractor.evaluate("lugin", pluginDescriptor) may work
since the first argument is irrelevant if string doesn't contain '.'.
But I'm more confused by the substring part of what .indexOf("/") is for.

And still, in my Mojo, the parameter with expression "${plugin}" is
causing PluginParameterException which indicates the value of it is null.

Regards
-Jiaqi

franz see wrote:
> Good day to you, Jiaqi,
>
> Why do you say that it will be evaluted to null?
>
> Cheers,
> Franz
>
>
> Jiaqi Guo wrote:
>
>> Hi there,
>>
>> I'm trying to find out the build-in variables for a maven2 plugin and
>> found the following code in
>> 
http://svn.apache.org/repos/asf/maven/components/tags/maven-2.0.4/maven-core/src/main/java/org/apache/maven/plugin/PluginParameterExpressionEvaluator.java
>>  line 217:
>>
>> ...
>>         else if ( expression.startsWith( "plugin" ) )
>>         {
>>             try
>>             {
>>                 int pathSeparator = expression.indexOf( "/" );
>>
>>                 PluginDescriptor pluginDescriptor =
>> mojoDescriptor.getPluginDescriptor();
>>
>>                 if ( pathSeparator > 0 )
>>                 {
>>                     String pathExpression = expression.substring( 1,
>> pathSeparator );
>>                     value = ReflectionValueExtractor.evaluate(
>> pathExpression, pluginDescriptor );
>>                     value = value + expression.substring( pathSeparator );
>>                 }
>>                 else
>>                 {
>>                     value = ReflectionValueExtractor.evaluate(
>> expression.substring( 1 ), pluginDescriptor );
>>                 }
>>             }
>>             catch ( Exception e )
>>             {
>>                 // TODO: don't catch exception
>>                 throw new ExpressionEvaluationException( "Error
>> evaluating plugin parameter expression: " + expression,
>>                                                          e );
>>             }
>>         }
>> ...
>>
>> If I didn't miss anything this code make the value of any parameter
>> expression starting with "plugin" to be null for sure, which will cause
>> PluginParameterException in
>> 
org.apache.maven.plugin.DefaultPluginManager.checkRequiredParameters(DefaultPluginManager.java:809).
>> Same thing happens to "settings" and "project".
>>
>> Is this a bug of maven-2.0.4? Is there any way to get pluginDescriptor
>> in Mojo?
>>
>>
>>
>> Regards
>>
>> --
>>
>>
>> Jiaqi Guo
>>
>> http://www.cyclopsgroup.org
>> [EMAIL PROTECTED]
>>
>>
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>> To unsubscribe, e-mail: [EMAIL PROTECTED]
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>>
>>
>>
>>
>
>


--


Jiaqi Guo

http://www.cyclopsgroup.org
[EMAIL PROTECTED]


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