class design - scala: reuse subclass implementation as a subclass of two different classes? -

to simplify actual code let's there 2 classes, 1 subclass of other:

class chair {    val canfold = false;    // ... }  class foldablechair extends chair {    val canfold = true;    // ... }  

and in implementation have potentially hundreds of other subclasses of chair or foldablechair:

class armchair extends ... {} class deckchair extends ... {}  //... etc 

for each of these subclasses, suppose each 1 has lengthy implementation want able have extend chair , extend foldablechair - without duplicating code. i'd without having subclass extended. possible somehow? need use traits this?

i'd able create particular instances of subclass extend chair , extend foldablechair, choice made when instantiating it. possible too? thanks!

edit: clarify, want this:

class armchair extends chair {}  class armchairfoldable extends foldablechair {} 

but implementation of armchair , armchairfoldable same. is, i'd not duplicate implementations.

you can use implementation trait; i.e., trait mix in class , provides additional members implementation.

example:

class chair {    // can use def rather val it's constant ,    // , doesn't need occupy field    def canfold = false     // ... }  class foldablechair extends chair {    override def canfold = true    // ... }  trait extensible extends chair {     // trait extends chair mean     // applicable chair or subclasses of chair     def extend = /* ... */ }  class foldableextensiblechair extends foldablechair extensible 

then can write:

val = new chair // bare-bones chair  // decide @ creation time 1 extensible val b = new chair extensible  val c = new foldablechair // non extensible  // use predefined class mixes in extensible val d = new foldableextensiblechair