override keyword

[Steven Schveighoffer]

"Zarathustra" wrote
> When 'override' is so really required?

The grammar of your question is ambiguous, but I'll try to explain override.

The override keyword *requires* that the function is an override of a base 
class' virtual function.  Not using the override will still override the 
virtual function, but if you put override it will fail to compile if there 
is no virtual function to override.

This isuseful, for example, if you are inheriting from a base class, and 
that base class changes the signature of a function that you chose to 
override, the compiler flags it as a failure.  This way, you can see what 
was affected by the base class change.  If you did not use the override 
keyword, then the code would still compile, but the new base class function 
would not be overridden, giving you potentially a disasterous silent bug.

For this reason, many people have suggested requiring the override keyword 
to override virtual functions.  But currently, it is still optional.

Hope this helps.

-Steve