Changes for page WebObjects with Scala

Summary

• Page properties (1 modified, 0 added, 0 removed)

Details

Page properties

Content

...	...	@@ -1,8 +1,8 @@
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 library make 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.
	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.
4	4
5		-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	8	|= Immutability | Collections //e.g: NSArray/NSMutableArray// | No | Yes
...	...	@@ -20,18 +20,21 @@
20	20
21	21	=== Why Use Scala? ===
22	22
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).
	23	+Scala can help you to write thread-safe code.
	24	+It has concurrency that is built-in to the standard library, primarily via Actors.
24	24
	26	+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).
	27	+
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.
	31	+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.
	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.
35	35
36	36	= WebObjects In Scala =
37	37
...	...	@@ -41,10 +41,9 @@
41	41
42	42	=== Thread-Safe Shared Vars ===
43	43
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.
	47	+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. This is not however true for mutable ##val## e.g: ##NSMutableArray##, ##scala.collection.mutable.ListBuffer##
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).
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
...	...	@@ -61,7 +61,7 @@
61	61
62	62	{{code}}
63	63
64		-object Talent {
	66	+object Talent extends EOGenericRecord {
65	65	val ENTITY_NAME = "Talent"
66	66
67	67	{{/code}}
...	...	@@ -76,6 +76,8 @@
76	76
77	77	==== Compacted imports ====
78	78
	81	+Two lines in Java are compacted into one in Scala.
	82	+
79	79	In Java:
80	80
81	81	{{code value="java"}}
...	...	@@ -196,10 +196,16 @@
196	196
197	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.  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) ==
	203	+== 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
	207	+{{note}}
	208	+
	209	+This is for Eclipse/WOLips IDE
	210	+
	211	+{{/note}}
	212	+
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:
...	...	@@ -215,12 +215,8 @@
215	215	1. [[Install the Scala eclipse IDE>>http://www.scala-ide.org/]]
216	216	1. Right-click on Application.java and run as a WOApplication (as usual).
217	217
218		-{{note}}
219		-
220	220	Application can be made into a Scala class as well, but then you will have to create a launcher in Eclipse manually.
221	221
222		-{{/note}}
223		-
224	224	== EO Templates ==
225	225
226	226	When you create your ##.eogen## file, be sure to make the following changes in the EOGenerator Editor: