Why is there no hybrid class-protocol type in Swift? -

i'm relatively new swift, , 1 thing has frustrated me inability create single type represents both class , protocol (similar class<protocol> * in objective-c). there protocol<protocol1, protocol2> operator can create new protocol type multiple protocols; question is, why not possible class , protocol?

i aware can accomplished using generics (e.g. <t: class t: protocol>). however, seems kludgy, in situations might want store type in instance variable don't want add generics class would considered implementation detail.

i better understand why not possible in swift. specifically, interested in how class , protocol types implemented (or defined) , why not possible combine them single type result.

what this?

let's declare protocol , class

protocol wearable { } class computer { } 

then let's declare 3 classes

class applewatch: computer, wearable { } class mac: computer { } class jeans: wearable { } 

and method accepts value must extend computer , conform wearable

func foo<t:computer t: wearable>(something:t) { } 

and let's test them:

foo(applewatch()) // ok foo(mac()) // error @ compile time foo(jeans()) // error @ compile time  

is mean?