Re: Non-null objects, the Null Object pattern, and T.init

[Adam D. Ruppe]

On Friday, 17 January 2014 at 14:06:59 UTC, Ola Fosheim Grøstad 
wrote:
Like if you delete a User object, then all "weak" pointers are 
set to a UnknownUser default object. So that you can call 
user.isLoggedIn() and get false, but you should be able to 
default to a different Class to get a different set of virtual 
calls.

This particular thing is easy enough to do with null too:
bool isLoggedIn(User user) {
    return user is null ? false : user.isLoggedInImpl();
}