Changes for page WebObjects with Scala

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1	1	=== What is Scala? ===
2	2
3		-Scala is a language for concurrent computing.
	3	+[[Scala>>http://en.wikipedia.org/wiki/Scala_(programming_language)]] is a language for concurrent computing.
4	4	In this day and age of multi-core processors, concurrent computing can't be ignored.
5	5
6	6	Many of Scala's features have been designed with concurrency in mind.
...	...	@@ -8,28 +8,26 @@
8	8
9	9	Here's a quick summary:
10	10
11		-|= |= Objective-C |= Java |= Scala
12		-|= Mutable/Immuable Datatypes | Collections //e.g: NSArray/NSMutableArray// | No | Yes
13		-|= Closures | Blocks (//Extension//) | No | Anonymous Functions
14		-|= Static variables | Yes | Yes | No
15		-|= Static methods or functions| Yes | Yes | No
16		-|= Concurrency | [[Grand Central Dispatch>>http://en.wikipedia.org/wiki/Grand_Central_Dispatch]] (//Extension//)| //Threads// |[[Actors>>http://en.wikipedia.org/wiki/Actor_model]]
17		-|= |= Weakly Typed |=--Strongly Typed--|= Strongly Typed
	11	+|= |= Objective-C |= Java |= Scala
	12	+|= Separation of Mutable & Immuable Datatypes | Collections //e.g: NSArray/NSMutableArray// | No | Yes
	13	+|= Closures | Blocks (//Extension//) | No | Anonymous Functions
	14	+|= Static variables | Yes | Yes | No
	15	+|= Static methods or functions | Yes | Yes | No
	16	+|= Concurrency | [[Grand Central Dispatch>>http://en.wikipedia.org/wiki/Grand_Central_Dispatch]] (//Extension//) | //Threads// | [[Actors>>http://en.wikipedia.org/wiki/Actor_model]]
	17	+|= |= Weakly Typed |= --Strongly Typed-- |= Strongly Typed
18	18
19	19	Other notable features include:
20	20
21		-|= |= Objective-C |= Java |= Scala
22		-|= Parametered methods | Yes //e.g: addObject: to~:// | No | Yes //e.g: add(object= ,to=)//
23		-|= Class composition | Categories | Interfaces | Traits
	21	+|= |= Objective-C |= Java |= Scala
	22	+|= Parametered methods | Yes //e.g: addObject: to~:// | No | Yes //e.g: add(object= ,to=)//
	23	+|= Class composition | Categories | Interfaces | Traits
24	24
25		-A fuller description of Scala can be found [[here>>http://en.wikipedia.org/wiki/Scala_(programming_language)]].
26		-
27	27	=== Why Use Scala? ===
28	28
29	29	Scala is inherently thread-safe.
30	30	It has concurrency that is effectively built-in to the language.
31	31
32		-So for WebObjects developers, Scala offers itself as a powerful, safe and easy-to-use solution for concurrent applications. (In other words, Scala Actors can be used for problems that would have normally required threads).
	30	+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).
33	33
34	34	=== Can WebObjects be Programmed In Scala? ===
35	35
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42	42
43	43	== EOs in Scala ==
44	44
45		-=== Thread-Safe Shared Vars ===
	43	+=== Thread-Safe Shared Vars ===
46	46
47		-Scala doesn't have static variables or methods. However, a class can have a //Companion Object// that will allow you to achieve something equivalent to static variables.
48		-One of the advantages of this approach is that it is **thread-safe**, so you don't have to worry about synchronizing access to these fields in a concurrent application.
	45	+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.
49	49
	47	+So you don't have to worry about synchronizing access to shared mutable fields in a concurrent application.
	48	+
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.
51	51
52	52	Java:
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67	67
68	68	{{/code}}
69	69
	69	+This value will be accessed exactly the same way in both languages:
	70	+
	71	+{{code}}
	72	+
	73	+Talent.ENTITY_NAME
	74	+
	75	+{{/code}}
	76	+
70	70	==== Compacted imports ====
71	71
72	72	Two lines in Java are compacted into one in Scala.
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155	155
156	156	{{/code}}
157	157
158		-==== Scala Annotations vs. Generic Accessors ====
	165	+==== Scala Annotations vs. Generated Accessors ====
159	159
160	160	An example of accessing variables in WebObjects with the following languages:
161	161
162		-|= |= Objective-C |= Java |= Scala
163		-|= getter | ##object name## | ##object.name()## | ##object.name##
164		-|= setter | ##object setName:aName## | ##object.setName(aName)## | ##object.name = aName##
	169	+|= |= Objective-C |= Java |= Scala
	170	+|= getter | ##object name## | ##object.name()## | ##object.name##
	171	+|= setter | ##object setName:aName## | ##object.setName(aName)## | ##object.name = aName##
165	165
166	166	Of course in Java, we may generate WebObjects classes with "get" methods as well in order to stick to convention.
167	167	In scala there is an additional convenience we may use to produce "get" and "set" methods in addition to the default Scala accessors - Scala Annotations.
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171	171
172	172	{{code}}
173	173
	181	+import scala.reflect.BeanProperty
	182	+
174	174	@BeanProperty var username = new String()
175	175	@BeanProperty var password = new String()
176	176	@BeanProperty var isAssistantCheckboxVisible = false
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179	179
180	180	== How to Use Scala Collections with EOF ==
181	181
182		-One of the benefits of Scala is its very powerful, concurrency-ready collection classes - primarily ##List##, ##Map##, ##Seq## and ##Set##.
	191	+One of the benefits of Scala is its very powerful, concurrency-ready collection classes - primarily ##List##, ##Map## and ##Set##.
183	183	Employing these instead of ##NSArray## and ##NSDictionary## in WebObjects/EOF may be challenging.
184	184
185	185	But one may modify the EO templates to produce API such as:
...	...	@@ -186,21 +186,25 @@
186	186
187	187	{{code}}
188	188
189		-def movies: NSArray[EOGenericRecord] = {
190		- storedValueForKey(_Studio.Keys.MOVIES).asInstanceOf[NSArray[EOGenericRecord]]
	198	+import scala.collection.JavaConversions._
	199	+
	200	+def movies = {
	201	+ storedValueForKey(_Studio.Keys.MOVIES).asInstanceOf[NSArray[Movie]]
191	191	}
192		-
193		-def moviesList: List[EOGenericRecord] = {
194		- movies.objects.toList
	203	+
	204	+def moviesList = {
	205	+ movies.asInstanceOf[java.lang.Iterable[Movie]].toList
195	195	}
196	196
197	197	{{/code}}
198	198
	210	+This employs a feature of Scala known as **implicit conversions** to automagically convert a NSArray (a Java Iterable) into a Scala Iterable.
	211	+
199	199	== 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
203		-{{note title="Note"}}
	216	+{{note}}
204	204
205	205	This is for Eclipse/WOLips IDE
206	206
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210	210
211	211	The following example is an almost 100% Scala WO app. In reality it is a mixed Java/Scala app:
212	212	All the EO logic and WO components are in Scala.
213		-Only the Application class is Java.
	226	+Only the Application class remains Java.
214	214
215	215	It is based on the D2W Movies example.
216	216
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218	218
219	219	=== Setup ===
220	220
221		-1. [[Install the Scala eclipse IDE>>http://www.scala-lang.org/node/94]]
222		-1. Install and start the OpenBase OBMovies database.
	234	+1. [[Install the Scala eclipse IDE>>http://www.scala-ide.org/]]
223	223	1. Right-click on Application.java and run as a WOApplication (as usual).
224	224
225		-==== EO Templates ====
	237	+== EO Templates ==
226	226
227	227	When you create your ##.eogen## file, be sure to make the following changes in the EOGenerator Editor:
228	228
229		-1. Point to the local [[Scala versions>>http://wiki.objectstyle.org/confluence/display/WOL/EOGenerator+Templates+and+Additions]] of the .eotemplate files for ##Entity## and ##//Entity//##
	241	+1. Point to the local [[Scala versions>>http://wiki.objectstyle.org/confluence/display/WOL/EOGenerator+Templates+and+Additions]] of the .eotemplate files for ##Entity## and ##Entity##
230	230	1. Change the File Names Extension to "scala"
231	231	1. In Destination Paths set the Superclass Package (e.g: base)
232	232	1. Uncheck Java under Options