annotations

[Peter Kriens]

> Meanwhile, let's say that I'm trying to get my module to work in two
> module systems - for the purposes of this example, Jigsaw and OSGi.
> Whenever I load it into Jigsaw, I need to import the module with
> OSGi's annotations (which are hopefully set up to be read by Jigsaw),
> and visa versa.  This isn't the end of the world, but with multiple
> module systems and user extensions for each, it's not hard to start
> imagining some real nightmare scenarios.
Nope, unknown annotations are ignored ...

Kind regards,

	Peter Kriens


On 17 apr 2009, at 21:15, Evan Cowden wrote:

>> I guess your argument against annotations doesn't translate into  
>> support
>> for the 'requires' keyword in module-info.java, right? We need some  
>> way
>> for a Java compiler to read raw dependency data, and for
>> module-system-specific metadata to qualify that data. Hence my  
>> proposal:
>>
>> // Non-dependency, post-classloading annotations make sense up here
>> @Copyright("Alex")
>> module M @ 1.5 {  // Or M : 1.5 as per Paul's comments
>>
>>   requires FOO BAR QUUX N at 1.6;
>>     // FOO BAR QUUX interpreted by a module system, to be identified
>>     // an attribute in module-info.class.
>> }
>>
>> Alex
>
> Interesting idea.  It's a move in the right direction, but I think
> you're still going to have the same problems.
>
> Let's flesh out that example:
>
> // You need to import the annotation classes
> import com.alex.Copyright;
> import com.sun.jigsaw.annotations.Jigsaw;
> import org.osgi.annotations.OSGi;
>
> // Non-dependency, post-classloading annotations make sense up here
> @Copyright("Alex")
> @Jigsaw("...")
> @OSGi("...")
> module M @ 1.5 {  // Or M : 1.5 as per Paul's comments
>
>   requires FOO BAR QUUX N at 1.6;
>     // FOO BAR QUUX interpreted by a module system, to be identified
>     // an attribute in module-info.class.
> }
>
> If the module-info.java works in the same was as package-info.java -
> at least in my understanding - then we'll wind up with a
> module-info.class.  This is then read in by the module system through
> the classloading process.  The classloader hits those import
> statements for the annotations and immediately replies, "huh?"
> (Forgive me if I'm mischaracterizing classloaders.)  The class never
> gets successfully loaded and you still can't get your metadata.
>
> Meanwhile, let's say that I'm trying to get my module to work in two
> module systems - for the purposes of this example, Jigsaw and OSGi.
> Whenever I load it into Jigsaw, I need to import the module with
> OSGi's annotations (which are hopefully set up to be read by Jigsaw),
> and visa versa.  This isn't the end of the world, but with multiple
> module systems and user extensions for each, it's not hard to start
> imagining some real nightmare scenarios.
>
> - Evan Cowden