NameError vs AttributeError

[Terry Reedy]

On 7/31/2012 4:49 PM, Chris Kaynor wrote:
> On Tue, Jul 31, 2012 at 1:21 PM, Terry Reedy <tjreedy at udel.edu
> <mailto:tjreedy at udel.edu>> wrote:
>
>     Another example: KeyError and IndexError are both subscript errors,
>     but there is no SubscriptError superclass, even though both work
>     thru the same mechanism -- __getitem__.  The reason is that there is
>     no need for one. In 'x[y]', x is usually intented to be either a
>     sequence or mapping, but not possibly both. In the rare cases when
>     one wants to catch both errors, one can easily enough. To continue
>     the example above, popping an empty list and empty set produce
>     IndexError and KeyError respectively:
>
>        try:
>          while True:
>            process(pop())
>        except (KeyError, IndexError):
>          pass  # empty collection means we are done
>
> There is a base type for KeyError and IndexError: LookupError.
>
> http://docs.python.org/library/exceptions.html#exception-hierarchy

Oh, so there is. Added in 1.5 strictly as a never-directly-raised base 
class for the above pair, now also directly raised in codecs.lookup. I 
have not decided if I want to replace the tuple in the code in my book.

-- 
Terry Jan Reedy