[Python-Dev] PEP 285: Adding a bool type

[Guido van Rossum]

> 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
> Guido> required.

[ARK]
> 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?

Probably.  We're inheriting implemetation.

--Guido van Rossum (home page: http://www.python.org/~guido/)