Let's say I have a System.Web.IHttpHandler
whose base class is ASP.login_aspx
whose base class is MyCMS.Admin.Login
whose base class is... etc... all the way back to System.Web.UI.Page
and of course, object
.
Why do I have to cast my IHttpHandler as MyCMS.Admin.Login
before I can access the members of that type and below?
Example:
IHttpHandler result = base.GetHandler(context, requestType, virtualPath, path);
bool isVisible = result.Visible;//Does not work
bool isVisible = ((MyCMS.Admin.Login)(result)).Visible;//Works
//Noting that Visible is a member of System.Web.UI.Page
For clarity, I'm not expecting that result.Visible should work, I just want to know why it doesn't.
Visible
is not a member of IHttpHandler
, so you should not expect to be able to call it on such a variable. It's a member of Page
, by way of Control
, I believe.
When you cast a variable to one of the base types/interfaces of the object's class, you can only call members that are on the type of the variable (or base classes/interfaces of that type).
The IHttpHandler interface is just that - an interface. It has no knowledge of a Visible
member since any class can implement this interface. What you ended up doing is casting to an object of a class that does inherit the Visible
member.
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