scala - Override field with parameterless method -

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I am currently learning Scala and I am reading Martin Ordesky's book (from the cover). In Chapter 10 I found this:

Enter image details here < P> Excellent I understand both and in this way. So I tried an example: 

  class father {def x = 1 // method} increases the child's dad in the class (overlays well x = 1; // field}   
 However, if you try to override an attribute with a method:  
  class father father {val x = 1; // field} class I get a compiler error:  
  The method x should be a static, irreversible value override (override def x = 1 // method)   
 Def X = 1   
 This does not work if  x  is in  dad   var :  
  Method x can not override a floating variable override def x = 1   
 so we have two cases (and I have two questions):  < Ul> 
  •   Trying to override an unqualified field:  In this order of guarantee,  x  will not be overridden by a method whose value varies more Until the time? Is there any other reason?  
  •   A The variable region is trying to override:  Why can not override an unqualified area? I initially thought that this is to avoid class users assigning values ​​to parameters without parameters, but then no parameter-based method should be allowed.    
     
     
     a  val  to  def  
     A  var  should be allowed to override at  def  what will it mean?

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