c# - Contravariant parameters? -

this stupid question but, have method use make syntax of page little more easy read

    public void do(delegate method, dispatcherpriority priority = dispatcherpriority.normal)     {         this.window.dispatcher.begininvoke(method, dispatcherpriority.background);     } 

then can write

        do(new action(() =>         {             //dostuff()         })); 

however, i'd move action method can write more simply:

        do(() =>         {             //dostuff()         })); 

but i'm bit sure how write contravariant parameter do method?

lambdas untyped, not possible.

if don't care method-arguments, appears case, why not change method signature :

public void do(action method,                dispatcherpriority priority = dispatcherpriority.normal) 

then, second sample work fine since compiler able implicitly convert lambda action.

if want accept instance of any delegate-type represents method takes no arguments, you'll have stick have.