[Python-Dev] PEP 285: Adding a bool type
ark at research.att.com
Sat Mar 30 17:04:13 CET 2002
Guido> Another argument for deriving bool from int: implementation
Guido> inheritance. A bool must behave just like an int, and this is
Guido> most easily accomplished this way: the bool type doesn't have
Guido> implementations for most operations: it inherits them from the
Guido> int type, which find a bool acceptable where an int is
Liskov substitutibility would seem to suggest deriving int from bool,
not the other way around. That is: If I have a program that uses bool
values, I can change it so that it uses int values without affecting
the behavior of the program. The reverse is not true.
I wonder if this is the circle-ellipse problem over again?
Andrew Koenig, ark at research.att.com, http://www.research.att.com/info/ark
More information about the Python-list