Fields (val or var) in scala class can get a getter (val) or setter/getter (var) automatically.

See this sample:

 scala> class Person {
      |   var age = 0
      | }
 class Person
   
 scala> tt.age
 val res16: Int = 0
   
 scala> tt.age=21
 // mutated tt.age
   
 scala> tt.age
 val res17: Int = 21
 

And we can also customize the setter/getter methods.

 scala> class Person {
      |   private var privateAge = 0
      |   def age = privateAge
      |   def age_=(newValue:Int) = {
      |     if (newValue > privateAge) privateAge = newValue
      |   }
      | }
 class Person
   
 scala> val fred = new Person
 val fred: Person = Person@c56c25b
   
 scala> fred.age
 val res21: Int = 0
   
 scala> fred.age=30
 // mutated fred.age
   
 scala> fred.age=21
 // mutated fred.age
    
 scala> fred.age
 val res22: Int = 30
 

This looks a bit different from ruby meta programming.

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