[Development] isValid() as a property

[Harri Porten]

On Fri, 29 Nov 2013, Tony Van Eerd wrote:

> in the cases I am looking at, if isValid() == false, then all the other 
> properties are invalid, and return "", -1, etc.  It really does mean the 
> whole object is invalid.
> 
> (except maybe an 'id', in the case of, say, a Battery object - the id 
> telling you which battery, and then isValid() saying that battery 
> doesn't (currently) exist.)

Why not use exists, present, active or something like it? But a C++ object 
for a physical object that does not exist... why is it there in the first 
place?

Harri.