swift - call generic function without params -

protocol idatasource:anyobject{     typealias ds;     typealias u;     func datasource(ds:ds, index:int?);     func datasource(ds:ds, data:[u]); }  class datasource<t:anyobject>{      var map = [nsmanagedobjectid:t]();     var data = [t]();     var ctrls:nshashtable = nshashtable.weakobjectshashtable();     func find(value:t)->int?;     var selected:t?;      func setneedsupdate<bar:idatasource bar.u==t,bar.ds==dsgen>(){         ctrl in self.ctrls.allobjects {             let client = ctrl as! bar;             client.datasource(self, data:self.data);         }     }     func foo(){         // error         setneedsupdate()         } } 

how can call method setneedsupdate()? compiler error " cannot invoke 'setneedsupdate' no arguments"

have found decision, decision demand parameter

func setneedsupdate<bar:idatasource bar.u==t,bar.ds==dsgen>(type:bar.type){     ctrl in self.ctrls.allobjects {         let client = ctrl as! bar;         client.datasource(self, data:self.data);     } } func foo<bar:idatasource bar.u==t,bar.ds==dsgen>(){     // error     setneedsupdate(bar.self)     }