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Changes for page WebObjects with Scala

Last modified by Ravi Mendis on 2011/05/10 02:10
From version 444.1
edited by John Huss
on 2010/12/03 16:45
Change comment: There is no comment for this version
To version 448.1
edited by Ravi Mendis
on 2010/12/23 23:48
Change comment: There is no comment for this version

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1 -XWiki.johnthuss
1 +XWiki.rmendis
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1 1  === What is Scala? ===
2 2  
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.
4 -In this day and age of multi-core processors, concurrent computing can't be ignored.
3 +[[Scala>>http://en.wikipedia.org/wiki/Scala_(programming_language)]] is a JVM language that is a hybrid of Object-Oriented and Functional styles. Its [[functional language>>http://en.wikipedia.org/wiki/Functional_programming]] foundations and built-in Actors library makes it especially attractive for concurrent computing. In this day and age of multi-core processors concurrent computing can not be ignored.
5 5  
6 -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.
7 -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:
8 8  
9 -Here's a quick summary:
10 -
11 11  |= |= Objective-C |= Java |= Scala
12 -|= Separation of Mutable & Immuable Datatypes | Collections //e.g: NSArray/NSMutableArray// | No | Yes
8 +|= Immutability | Collections //e.g: NSArray/NSMutableArray// | No | Yes
13 13  |= Closures | Blocks (//Extension//) | No | Anonymous Functions
14 14  |= Static variables | Yes | Yes | No
15 15  |= Static methods or functions | Yes | Yes | No
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32 32  === Can WebObjects be Programmed In Scala? ===
33 33  
34 34  Yes. It is very simple.
35 -Scala compiles to java bytecode. Hence using it with WebObjects is fairly straightforward.
31 +Scala compiles to java bytecode.
36 36  
37 -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 is rather slow and still very buggy.
33 +Furthermore, being a multi-paradigm language grants Scala easy WebObjects-interoperability.
38 38  
35 +===== Caveats =====
36 +
37 +Tool support is 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]] is rather slow and still very buggy.
38 +
39 39  = WebObjects In Scala =
40 40  
41 41  The following highlights some of the differences between Java and Scala in WebObjects:
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190 190  
191 191  == How to Use Scala Collections with EOF ==
192 192  
193 -To use the Scala Collections API with an NSArray or NSDictionary you simply need to add an import:import scala.collection.JavaConversions.
193 +To use the Scala Collections API with an NSArray or NSDictionary you simply need to add an import:
194 194  
195 -Then you can access the typical Scala collection methods directly on NSArray.  This employs a feature of Scala known as implicit conversions to automagically cast a NSArray (a Java Iterable) into a Scala Iterable while leaving the actual object unchanged.  Alternatively, you could generate an actual new scala.List instance by calling myNSArray.toList.
195 +{{code value="java"}}
196 196  
197 +import scala.collection.JavaConversions._
198 +
199 +{{/code}}
200 +
201 +After that, you may access the typical Scala collection methods directly on NSArray.  This employs a feature of Scala known as implicit conversions to automagically cast a NSArray (a Java Iterable) into a Scala Iterable while leaving the actual object unchanged.  Alternatively, you could generate an actual new scala.List instance by calling myNSArray.toList.
202 +
197 197  == How to Add Scala to a WO Project ==
198 198  
199 199  {{include value="WOL:Adding Scala Support to a WOLips Project"}}{{/include}}