Re: mixins etc.

Let me make sure i understand the Mixin annotation: it's for if the Mixin extension is written in a java class?
Alex Tkachman wrote:

Could you provide test case please. It will help to fix :)

On Wed, Apr 9, 2008 at 12:20 PM, Robert O'Connor rob@... wrote:
  

 Shrug, it comes with the territory of using unreleased code :) I linked the
mailing list post, so if people read it, they'll know this... but
regardless, i like it. Also, mixins classes can only contain one method
right? I ran into a lovely erm, StackOverFlow when i added more than one
method to my mixin class..


 Alex Tkachman wrote:
 Thank you, Rob. But please be aware that it is experimental feature
and can be reverted from trunk in any moment or seriously modifed.
I mean it is a bit too early to popularize it :)

On Wed, Apr 9, 2008 at 12:01 PM, Robert O'Connor rob@... wrote:


 Alex, good job! I played with your mixin syntax in an unsavory way,
overloaded the subtraction operator to add the two integers:
http://robbyoconnor.blogspot.com/2008/04/new-groovy-mixins-syntax.html

 Again, good job!
 -rob
 Alex Tkachman wrote:

 See comments below

On Wed, Apr 9, 2008 at 11:36 AM, Dierk König dierk.koenig@... wrote:



cool ;-)

 Thanks a lot for the implementation and the comprehensive
 description!


 | So what is mixin?
 |
 | Mixin is usual category-like class, which provides methods to
 | extend some (or several) existing classes.
 |
 | class ArrayListExt {
 | static def newArrayListMethod (ArrayList self) {
 | "result of newArrayListMethod "
 | }
 | }

 ... except that categories can be used to define
 methods on a combination of classes that work together
 to fulfill a common purpose. E.g.
 defining something like

 class IntCodec {
 static String encode (Integer self) { ... }
 static Integer decode (String self) { ... }
 }

 is not possible with mixins, since they only affect
 one class at a time.

 Right?


 In this case you will need to apply mixin separately to String and Integer.

Initially I had syntax DefaultGroovyMethods.mixin IntCodec but as
Jochen noticed in thread on global categories it brings a bit too much
danger, so right now this functionality is banned. But it is very easy
to return it back :)



 Also, categories have a scope of use. Mixins don't,
 right?


 Right, mixins has no scope.



 Is there also any difference in the affected threads?
 (I vaguely remember this has been discussed on the
 list before... sorry)



 No threading involved. Another difference from categories.



 | simple use of it
 |
 | ArrayList.mixin ArrayListExt

 how about setting the scope like

 ArrayList.mixin (ArrayListExt) {
 // new methods available here
 }
 // but not here anymore



 Assuming that ArrayListExt effects ArrayList (and hierarchy) only it
is equivalent to using category.



 ?

 | @Mixin(MyClassExt)
 | class MyClass {
 | def result () {
 | longRunningJavaMethod ()
 | }
 | }
 |
 | and write for example in Java
 |
 | public MyClassExt {
 | public static Set<Collection> longRunningJavaMethod (MyClass
 | self) { /// }
 | }

 so cool and very powerful ;-)

 reminds me on my old Ruby days...



 | Another nice feature for groovy objects is ability to do per
 | instance mixins

 dito


 | 1) Methods of the class and super classes (including all
 | their modifications except categories)
 | 2) DGM methods
 | 3)
 | 4) EMC methods
 | 5) methods of categories in use

 well explained!

 Now how about this:

 class A { def foo() {'A'} }
 class B extends A { def foo() {'B'} } // subclass overrides method

 class M { static void foo(A self) {'M'} } // mixin redefines method

 A.mixin M

 println( new B().foo() )

 ???? %-)


 In theory expected behaviour is to print 'B' because B defines more
specific method. But new B().super.foo () (not legal syntax of course)
should print 'M' In practice, test case needed :)



 cheers
 Dierk


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