Changes for page WebObjects with Scala

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1	1	=== What is Scala? ===
2	2
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>>http://en.wikipedia.org/wiki/Actor_model]] library make it especially attractive for concurrent computing. (Scala is an abbreviation for "scalable" hinting at its design goals).
	3	+[[Scala>>http://en.wikipedia.org/wiki/Scala_(programming_language)]] 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.
4	4
5		-In this day and age of multi-core processors concurrent computing can not be ignored. Many of the design features of Scala have been chosen with concurrency in mind, some of which may not be unfamiliar to Objective-C or WebObjects developers. Here's a summary:
	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:
6	6
7	7	|= |= Objective-C |= Java |= Scala
8		-|= Immutability | Partial - via collections //e.g: NSArray/NSMutableArray// | No | Yes
9		-|= Closures | Yes - via Blocks (//Extension//) | No | Yes - via Anonymous Functions
	8	+|= Immutability | Collections //e.g: NSArray/NSMutableArray// | No | Yes
	9	+|= Closures | Blocks (//Extension//) | No | Anonymous Functions
10	10	|= Static variables | Yes | Yes | No
11		-|= Static methods | Yes | Yes | No
12		-|= Concurrency | Yes - via [[Grand Central Dispatch>>http://en.wikipedia.org/wiki/Grand_Central_Dispatch]] (//Extension//) | //Yes - via Threads// | Yes - via [[Actors>>http://en.wikipedia.org/wiki/Actor_model]]
	11	+|= Static methods or functions | Yes | Yes | No
	12	+|= Concurrency | [[Grand Central Dispatch>>http://en.wikipedia.org/wiki/Grand_Central_Dispatch]] (//Extension//) | //Threads// | [[Actors>>http://en.wikipedia.org/wiki/Actor_model]]
13	13	|= |= Weakly Typed |= --Strongly Typed-- |= Strongly Typed
14	14
15	15	Other notable features include:
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16	16
17	17	|= |= Objective-C |= Java |= Scala
18	18	|= Parametered methods | Yes //e.g: addObject: to~:// | No | Yes //e.g: add(object= ,to=)//
19		-|= Class composition | Yes - via Categories | Yes - via Interfaces | Yes - via [[Traits>>http://en.wikipedia.org/wiki/Trait_(computer_science)]]
	19	+|= Class composition | Categories | Interfaces | Traits
20	20
21	21	=== Why Use Scala? ===
22	22
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25	25	=== Can WebObjects be Programmed In Scala? ===
26	26
27	27	Yes. It is very simple.
28		-By virtue of being a JVM-language, Scala compiles to java bytecode.
	28	+Scala compiles to java bytecode.
29	29
30	30	Furthermore, being a multi-paradigm language grants Scala easy WebObjects-interoperability.
31	31
32	32	===== Caveats =====
33	33
34		-Legacy tool support is often cited as a weak point. The [[Eclipse Scala plugin>>http://www.scala-ide.org]] has been found to be slow at times and sometimes buggy.
	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	35
36	36	= WebObjects In Scala =
37	37
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44	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.
45	45
46	46	You don't have to worry about synchronizing access to shared mutable fields in a concurrent application.
47		-(This is not however true when for example you have a ##val## declared as a ##NSMutableArray##. You will still have to synchronize when adding to or removing from this mutable field).
	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.
48	48
49	49	The following is an example of the use of a //Companion Object// for Talent in Scala instead of Talent static fields in Java.
50	50
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61	61
62	62	{{code}}
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64		-object Talent {
	64	+object Talent extends EOGenericRecord {
65	65	val ENTITY_NAME = "Talent"
66	66
67	67	{{/code}}
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76	76
77	77	==== Compacted imports ====
78	78
	79	+Two lines in Java are compacted into one in Scala.
	80	+
79	79	In Java:
80	80
81	81	{{code value="java"}}
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162	162
163	163	==== Scala Annotations vs. Generated Accessors ====
164	164
165		-Here's an example of accessing variables in the following languages:
	167	+An example of accessing variables in WebObjects with the following languages:
166	166
167	167	|= |= Objective-C |= Java |= Scala
168	168	|= getter | ##object name## | ##object.name()## | ##object.name##
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194	194
195	195	{{/code}}
196	196
197		-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.
	199	+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.
198	198
199		-== How to Add Scala to a WO Project (in Eclipse) ==
	201	+== How to Add Scala to a WO Project ==
200	200
201	201	{{include value="WOL:Adding Scala Support to a WOLips Project"}}{{/include}}
202	202
	205	+{{note}}
	206	+
	207	+This is for Eclipse/WOLips IDE
	208	+
	209	+{{/note}}
	210	+
203	203	== WO Scala Example ==
204	204
205	205	The following example is an almost 100% Scala WO app. In reality it is a mixed Java/Scala app: