c# - Why is TypeDescriptor.GetProperties behaving different for types and objects when working with ICustomTypeDescriptor -

i created generic class group implements icustomtypedescriptor. adds properties of generic type parameter own properties.

    private void initializedisplayedproperties()     {         _displayedproperties.add(typedescriptor.getproperties(typeof(group<t>))["lastitem"]);         _displayedproperties.add(typedescriptor.getproperties(typeof(group<t>))["groupid"]);         _displayedproperties.add(typedescriptor.getproperties(typeof(group<t>))["count"]);          foreach (propertydescriptor mydescr in typedescriptor.getproperties(typeof(t)))         {             _displayedproperties.add(mydescr);         }     } 

why following code behave different?

typedescriptor.getproperties(typeof(group<igroupedobject>)).count //returns 3 items of group typedescriptor.getproperties(new group<igroupedobject>()).count //returns 31 items of group , generic type parameter 

i assume must have fact properties generated @ instance time of object. isn't number of attributes defined used types?

is possible work around behaviour without instantiating type?

i assume actual type implements icustomtypedescriptor; if case, typedescriptor.getproperties(object) api can access data, isn't willing create ad-hoc instance properties (and indeed, pretty common if type implements icustomtypedescriptor, properties vary per instance, wouldn't useful anyway).

if want entire type support this, need create , register typedescriptionprovider. works @ higher level, , allows custom properties apply type without needing consider instance. nice thing automatically apply lists etc, without needing implement itypedlist.

so basically: research typedescriptionprovider.