[Tutor] validation

[Terry Carroll]

On Tue, 28 Aug 2007, Kent Johnson wrote:

> Terry Carroll wrote:
> 
> > 1A) a variation of option 1 (which is why I said "depending on how you
> > count" above):  duck-typing with error recovery.
> > 
> > def incr(n):
> >   "returns an incremented value of n, or None if n is not incrementable"
> >   try:
> >     return n + 1
> >   except:
> >     return None
> > 
> > This will try to return a value equal to N + 1, but if n does not quack 
> > like a duck, it just returns None (and it's up to the caller to deal with 
> > it).
> 
> This is generally a bad idea. The problem is that you depend on the 
> caller checking the return value for None. 

Agreed.  I was just trying to come up with a short example of catching the
exception and doing something different because of it.  Admittedly, 
returning None is not much of an "error recovery."