vb.net - So a VB interface can't have shared functions. Is there an alternative to creating dummy objects? -

to avoid getting weeds on particular program, let me create simplified case.

i have generic class should work on variety of objects. each of objects must implement interface.

what want like:

public interface genthing     shared function thing_name() string ' doesn't work! can't shared!     sub fillone(row datarow) end interface  public class thing1   implements genthing     public shared function thing_name() string implements genthing.thing_name         return "thing number one"     end function      public sub fillone(row datarow) implements genthing.makeone         ... bunch of work ...     end sub end class  public class thingutil(of t {genthing,new})     public function getlist(id integer) list(of t)       dim name=t.thing_name() ' doesn't work!       dim ds dataset=getdata(name,id) ' bunch of work here that's whole point of class not relevant question       dim my_list = new list(of t)       each row datarow in ds.tables(0).rows           dim my_t = new t()           my_t.fillone(row)           my_list.add(my_t)       next       return my_list     end function end class 

do problem? need every class implements interface have function returns "name" used data needed create instance of object. need know name before create instance, because need able create instance. vb doesn't allow interface have shared function, want write doesn't work.

so i've done this:

i make thing_name not shared.

then instead of "dim name=t.thing_name()", write

dim dummy = new t() dim name = dummy.thing_name() 

okay, works, seems ugly. create instance of object, overhead that involves, piece of constant text.

is there better way? or making big deal out of nothing?

update

i see 2 people voted close question on grounds same "why can't have shared functions in interface?"

i not asking why can't have shared. saying, given can't, how solve particular problem?

there's no simple way of fixing this, no.

depending on thing_name does, however, might approach things in different way. if each implementation returns constant value, it's metadata class - , described in attribute instead, can fetched @ execution time. (see type.getcustomattributes.) unfortunately can't enforce types implementing interface decorated attribute - could write unit test check pretty easily.

if thing_name needs work @ execution time, that's tougher. potentially well-known shared method name instead , execute via reflection (and again have unit tests check it's implemented properly).