Optionally saves your skin

optionally-saves-your-butt.scala

scala> // Problem: Some java apis return nulls.                                                         

scala> System.getenv("PROBABLY_NOT_DEFINED_RUBISH_NAME")                                                
res0: java.lang.String = null

scala> System.getenv("PROBABLY_NOT_DEFINED_RUBISH_NAME").split(",")
java.lang.NullPointerException
	at .<init>(<console>:7)
	at .<clinit>(<console>)
	at RequestResult$.<init>(<console>:9)
	at RequestResult$.<clinit>(<console>)
	at RequestResult$scala_repl_result(<console>)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at scala.tools.nsc.Interpreter$Request$$anonfun$loadAndRun$1$$anonfun$apply$18.apply(Interpreter.scala:981)
	at scala.tools.nsc.Interpreter$Request$$anonfun$loadAndRun$1$$anonfun$apply$18.apply(Interpreter.scala:981)
	at scala.util.control.Exception$Catch.apply(Exception.scala:79)
	at scala.tools.nsc...

scala> // Solution: `optionally` defined in gist below.

scala> optionally(System.getenv("PROBABLY_NOT_DEFINED_RUBISH_NAME"))
res1: Option[java.lang.String] = None

scala> optionally(System.getenv("PATH"))                            
res2: Option[java.lang.String] = Some(/Users/f/.rvm/gems/ruby-1.8.7-p302/bin:/Users/f/.rvm/gems/ruby-1.8.7-p302@global/bin:/Users/f/.rvm/rubies/ruby-1.8.7-p302/bin:/Users/f/.rvm/bin:/Users/f/Library/homebrew/bin:/Users/f/Library/homebrew/Cellar/python/2.7/bin:/Users/f/Library/homebrew/sbin:/Users/f/bin:/Users/f/.cljr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin:/Users/f/Workshop/Library/scala/dist/current/bin)

scala> optionally(System.getenv("PATH")).getOrElse("").split(":").map(_.split("/"))
res3: Array[Array[java.lang.String]] = Array(Array(, Users, f, .rvm, gems, ruby-1.8.7-p302, bin), Array(, Users, f, .rvm, gems, ruby-1.8.7-p302@global, bin), Array(, Users, f, .rvm, rubies, ruby-1.8.7-p302, bin), Array(, Users, f, .rvm, bin), Array(, Users, f, Library, homebrew, bin), Array(, Users, f, Library, homebrew, Cellar, python, 2.7, bin), Array(, Users, f, Library, homebrew, sbin), Array(, Users, f, bin), Array(, Users, f, .cljr, bin), Array(, usr, bin), Array(, bin), Array(, usr, sbin), Array(, sbin), Array(, usr, local, bin), Array(, usr, X11, bin), Array(, Users, f, Workshop, Library, scala, dist, current, bin))

scala> optionally(System.getenv("PROBABLY_NOT_DEFINED_RUBISH_NAME")).getOrElse("").split(":").map(_.split("/"))
res4: Array[Array[java.lang.String]] = Array(Array())

scala> val from =  "[email protected],username;[email protected],anotheruser;[email protected]"
from: java.lang.String = [email protected],username;[email protected],anotheruser;[email protected]

scala> optionally(from).getOrElse("").split(";").map(_.split(",")).collect({ case Array(u,n) => (u,n)})
res6: Array[(java.lang.String, java.lang.String)] = Array(([email protected],username), ([email protected],anotheruser))

scala> optionally(null).getOrElse("").split(";").map(_.split(",")).collect({ case Array(u,n) => (u,n)})
res7: Array[(java.lang.String, java.lang.String)] = Array()

optionally.scala

scala> def optionally[T](any:T):Option[T] = any match { 
     |     case null => None
     |     case None => None 
     |     case _ => Some(any)  
     |   }
optionally: [T](any: T)Option[T]