"Casper =?UTF-8?B?RsOmcmdlbWFuZCI=?= <shorttail gmail.com> writes:

Is there any loss in performance instantiating an interface 
variable as a final class implementing only that interface, as 
opposed to a class variable?

"Steven Schveighoffer" <schveiguy yahoo.com> writes:

On Mon, 03 Mar 2014 21:48:16 -0500, Casper F=C3=A6rgemand <shorttail gma=
il.com>  =

wrote:

 Is there any loss in performance instantiating an interface variable a=

s  =

 a final class implementing only that interface, as opposed to a class =

 =

 variable?

You mean the difference between:

final class C : I {...}

// this
I i =3D new C;

// and this
C c =3D new C;

???

The difference in performance is huge. As a final class, no virtual call=
s  =

are needed. In itself, this is not a huge deal, as a virtual call is not=
  =

too much worse than a standard call.

However, method calls on the concrete class can be inlined, and an inlin=
e  =

call is generally very quick when compared to any kind of other call.

-Steve