vb.net - How do I determine if a class member exists? -

i have public subroutine called many classes. however, need in subroutine pertains small number of classes call it. instead of going , adding property of existing classes, check see see if class has property , if so, it. can't seem figure out how check existence of member without getting error.

for example:

public class_1       public a1 string = ""     public sub new()        ' when button clicked call subroutine "check()"    end sub  end class  public class_2       public a1 string = ""      public a2 integer = 0     public sub new()        ' when button clicked call subroutine "check()"    end sub  end class  public class whatever      public sub check(sender object)        if sender.a2 = 0        '        end if     end sub  end class 

i have tried such things as

if not(sender.a2 nothing) if isnothing(sender.a2) 

but can't past fact error using "sender.a2" since a2 not member of sender.

how can check see if a2 member of sending class without using "sender.a2"?

if want see field exists need this:

dim fi fieldinfo = sender.gettype().getfield("nameoffieldhere") if fi isnot nothing    'field exists value     dim o object = fi.getvalue(sender) end if 

take @ documentation type.getfield method (string) there overloads available too.