c# - Storing object implementing a generic interface in a collection -

I have several classes that all IWidget & lt; T & gt; Implementing the interface. I would like to add them to the list, so I define something like this:

  list & lt; IWidget & lt; T & gt; & Gt; _widgetList;   
 There is no complaint about the compiler T:  
 
 Error 1 type or namespace name 'T' could not be found (whether you use the Director Are not the assemblies missing the context?)   
 Is there a way to define a list of IWidget and still have a generic interface?  
 I am using .NET 3.5 SP1.   
 
 
 There are a few ways to do this:  
  1)  You need a non-common route:  
  Public interface IWidget {...} Public Interface IWidget & lt; T & gt; : IWidget {...}   
 So that you  list & lt; IWidget & gt; _widgetList;   
 
  2)  You can use the  dynamic  s or polymorphism with a coat / co-vibration, but your To play in accordance with the rules of the rules,   & lt; T & gt;  should not be a value type  and you have to enter after entering, but not when it is added, like this:  
  IWidget & lt; String & gt; Xxx = ...; Var widgetListDyn = New list & lt; IWidget & lt; Dynamic & gt; & Gt; (); Var widgetListObj = new list & lt; IWidget & lt; Object & gt; & Gt; (); WidgetListDyn.Add (xxx); WidgetListObj.Add (xxx);   
 
  3)  or you can match two methods:  
  Public Interface: IWidget: IWidget & lt; Object & gt; {}   
 and you  list & lt; IWidget & gt; You can use. _Vidit list;  with this technique you  .add () :  
  list  
 
  4)  You can go about this in the final way:  
  Public class IWidgetList & lt; T & gt; : List & lt; IWidget & lt; T & gt; & Gt; {}   
 Which would be useful, if you plan to declare several lists written in, then you should:  list & lt; IWidget & lt; TYPE & gt; & Gt;  and instead you can use it:  IWidgetList & lt; TYPE & gt;  and it's similar