Scala Case Class

Scala Case Class

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What does case classes do again? You can just think of him as a normal class, but slightly different, summed up as follows:

1. No need to write new, but can write

2. The default is public, which is called from anywhere

3. The ToString is implemented by default

4. Cannot be inherited

Official text:

It makes define case classes if pattern matching are used to decompose data structures.

Of course, it's a bit biased to have meaning in the pattern matching, at least some old programmers have other ideas:

Get auto-generated equals, Hashcode, toString, Static apply () for shorter initialization, etc.

such as the Xia Guan Network example,

/** *  @author:  lenovo (2015-04-13 13:37)  *///  Abstract Parent class abstract class term//  case classcase class var (name: string)  extends Term// case  Classcase class fun (arg: string, body: term)  extends Term// case  Classcase class app0 (f: term, v: term)  extends termobject termtest  extends app {  def printterm (term: term)  {     Term match {      case var (n)  =>         print (n)       case fun (x, b)  =>         print ("^"  + x +  ".")         printterm (b)       case app0 (F, V)  =>        print ("(")         printterm (f)          print (" ")         printterm (v)         print (")")     }  }   Def isidentityfun (term: term): boolean = term match {     case fun (X, var (y))  if x == y => true     Case _ => false  }  val id = fun ("X",  Var ("X"))   val t = fun ("X",  fun ("Y",  app0 (Var ("X"),  var ("Y")))    Printterm (t)   println  println (Isidentityfun (ID))   println (IsIdentityFun (t))}

Run

^x.^y. (x y) TrueFalse

Scala Case Class