val and object inside a scala class?

Question

What is the difference between declaring a field as val, lazy val and object inside a scala class, as in the following snippet:

<

Answer 1

This is not a structural type: val a = new A { def foo = 1 }

It creates a unique anonymous subclass; a.foo invokes foo in that class.

x here is a structural type: def bar( x: { def bass: Int} )

x.bass will introspect x (of unknown type) to find a method with name 'bass'. It will work with fish or musical instruments. ;)

One difference between the lazy val and object is this:

var someA = (new B).a3
someA = (new B).a3 // ok

var anotherA = (new B).a2
anotherA =  = (new B).a2 // compile error