some useful xtend active annotations

[Salvatore Romeo]

I just published some active annotations we use in our team. You can find them here:

https://github.com/plugback/active/tree/master/src/main/java/com/plugback/active

as specified in the sources, part of the utilities classes were taken from https://github.com/oehme/xtend-contrib, thanks to the author.

In some previous posts we talked about implementing default interface methods in xtend for java versions prior to java 8. The @Mix active annotation does just this:

https://github.com/plugback/active/blob/master/src/main/java/com/plugback/active/mix/Mix.xtend

please refer to TestMix in src/test/java for how to use it. It's still a basic version and more documentation will come!

[Victor]

Hi,

That's cool, I have just two questions:

1) why don't you depend on xtend-contrib instead of copying classes provided by it?
2) why do you provide your own version of annotation already in xtend (Data and Property)

Victor

[Salvatore Romeo]

1) definitely. it's on the TODO list.

2) because the included @Data and @Property add a prefix, the underscore (_) symbol, to each field. JPA and json serialization don't play well with this, so we implemented our own annotations. This problem was already discussed here: https://groups.google.com/forum/#!searchin/xtend-lang/Property$20underscore/xtend-lang/lSoBkpH24m4/4Je585PG-BwJ 

There are also some small differences: 

- Our @Property annotation will make all set methods return the this object, so to chain setters. 

- Our @Data implementation requires to define a constructor having some parameters. The parameters will be added as fields.

[John Kozlov]

Great!

Also, loot at my active annotations: https://github.com/orionll/xtension-annotations

Most interesting, I think, are getters, that support laziness: https://github.com/orionll/xtension-annotations/blob/master/src/main/java/com/github/xtension/annotations/Getter.xtend

[Victor]

Thanks, that makes sense :)

I also made some active annotation that build on top of the Cached annotation from xtend-contrib (to reset them when a certain method is called) and some useful extensions for functionaljava, mason and java.
The code is there:
https://wwwsecu.irit.fr/hg/SMAC/victor-noel-phd/contrib-dev/ (l/p: anon/anon)
and the maven repository is there:
http://www.irit.fr/~Victor.Noel/maven-repos/

Victor

[Victor]

I'm wondering, isn't a lazy field the same as a Cached method as in xtend-contrib ?

[John Kozlov]

Hm, it looks like they provide the same functionality. I'd even say that @Cached is a bit better, because there is no problem with ambiguity (does x mean x or getX()?). One minor difference is in the implementation. Mine supports primitive types via an additional bolean field. xtend-contrib is using boxing instead, which is a bit unsafe.

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[Salvatore Romeo]

good to see other useful uses of active annotations :-)

[John Kozlov]

I hope that someday Xtend will have a big set of built-in annotations. @ToString, @Singleton, @Cached, @Mixin and others should defenitely be part of the standard library.

[Victor]

I think that's the role xtend-contrib wants to play.

Maybe it would be coherent for interested people to try to contribute to it when they have active annotations such as the one you cited :)