Changes for page WebObjects with Scala

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1	1	=== What is Scala? ===
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3		-[[Scala>>http://en.wikipedia.org/wiki/Scala_(programming_language)]] is a JVM language that is a hybrid of Object-Oriented and Functional styles. It is useful as complete general purpose replacement for Java. But its built-in Actors library makes it especially attractive for concurrent computing. In this day and age of multi-core processors, concurrent computing can't be ignored.
	3	+[[Scala>>http://www.scala-lang.org/]] is a modern, multi-paradigm JVM language that is most often compared to [[Groovy>>http://en.wikipedia.org/wiki/Groovy_(programming_language)]], [[Clojure>>http://en.wikipedia.org/wiki/Clojure]] or [[Erlang>>http://en.wikipedia.org/wiki/Erlang_(programming_language)]]. Its [[functional language>>http://en.wikipedia.org/wiki/Functional_programming]] foundations and built-in Actors library makes it especially attractive for concurrent computing. (Scala is an abbreviation for "scalable" hinting at its design goals). In this day and age of multi-core processors concurrent computing can not be ignored.
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5		-Many of Scala's features have been designed with concurrency in mind, primarily a preference for immutability and the use of other functional language paradigms.
6		-Some of these may not be unfamiliar to Objective-C or WebObjects developers.
	5	+Many of Scala's features have been designed with concurrency in mind, some of which may not be unfamiliar to Objective-C or WebObjects developers. Here's a summary:
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8		-Here's a quick summary:
9		-
10	10	|= |= Objective-C |= Java |= Scala
11		-|= Separation of Mutable & Immuable Datatypes | Collections //e.g: NSArray/NSMutableArray// | No | Yes
	8	+|= Immutability | Collections //e.g: NSArray/NSMutableArray// | No | Yes
12	12	|= Closures | Blocks (//Extension//) | No | Anonymous Functions
13	13	|= Static variables | Yes | Yes | No
14	14	|= Static methods or functions | Yes | Yes | No
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24	24	=== Why Use Scala? ===
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26		-Scala can help you to write thread-safe code.
27		-It has concurrency that is built-in to the standard library, primarily via Actors.
	23	+For WebObjects developers, Scala offers itself as a powerful, safe and easy-to-use solution for [[concurrent computing>>Building Concurrent Applications with WebObjects and Scala]]. (In other words, Scala Actors can be used for problems that would have normally required threads).
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29		-So for WebObjects developers, Scala offers itself as a powerful, safe and easy-to-use solution for [[concurrent applications>>Building Concurrent Applications with WebObjects and Scala]]. (In other words, Scala Actors can be used for problems that would have normally required threads).
30		-
31	31	=== Can WebObjects be Programmed In Scala? ===
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33	33	Yes. It is very simple.
34		-Scala compiles to java bytecode. Hence using it with WebObjects is fairly straightforward.
	28	+Scala compiles to java bytecode.
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36		-However, tool support is a weak point. You should use Eclipse 3.6 with bundle-less WO builds.  If your Application class is in Scala then you will have to create an Eclipse launch configuration manually. One weird thing is that once you add the Scala nature to a WO project WOD completion will stop working - this is unfortunate. Also the [[Scala plugin>>http://www.scala-ide.org]] is rather slow and still very buggy.
	30	+Furthermore, being a multi-paradigm language grants Scala easy WebObjects-interoperability.
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	32	+===== Caveats =====
	33	+
	34	+Legacy tool support is often cited as a weak point. If your Application class is in Scala then you will have to create an Eclipse launch configuration manually. Also the [[Scala plugin>>http://www.scala-ide.org]] can be slow at times and sometimes buggy.
	35	+
38	38	= WebObjects In Scala =
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40	40	The following highlights some of the differences between Java and Scala in WebObjects:
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44	44	=== Thread-Safe Shared Vars ===
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46		-Scala doesn't have static variables or methods. Instead Scala employs the [[Singleton Pattern>>http://en.wikipedia.org/wiki/Singleton_pattern]] which is built into the language and is **thread-safe**: a class can have a //Companion Object// that will allow you to achieve something equivalent to static variables - but better. Is this true?  I don't think Scala "object" instances (with the object keyword) are guaranteed to be thread-safe; they are just singletons
	44	+Scala doesn't have static variables or methods. Instead Scala employs the [[Singleton Pattern>>http://en.wikipedia.org/wiki/Singleton_pattern]] which is built into the language and is **thread-safe**: a class can have a //Companion Object// that will allow you to achieve something equivalent to static variables - but better.
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48		-So you don't have to worry about synchronizing access to shared mutable fields in a concurrent application.
	46	+You don't have to worry about synchronizing access to shared mutable fields in a concurrent application.
	47	+This is not however true for mutable ##val## e.g: ##NSMutableArray##, ##scala.collection.mutable.ListBuffer## which you will have to synchronize the adding to or removing from.
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50	50	The following is an example of the use of a //Companion Object// for Talent in Scala instead of Talent static fields in Java.
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224	224	1. [[Install the Scala eclipse IDE>>http://www.scala-ide.org/]]
225	225	1. Right-click on Application.java and run as a WOApplication (as usual).
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	226	+{{note}}
	227	+
227	227	Application can be made into a Scala class as well, but then you will have to create a launcher in Eclipse manually.
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	230	+{{/note}}
	231	+
229	229	== EO Templates ==
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231	231	When you create your ##.eogen## file, be sure to make the following changes in the EOGenerator Editor: