PEP 285: Adding a bool type

[Martin v. Loewis]

philh at comuno.freeserve.co.uk (phil hunt) writes:

> On Sat, 30 Mar 2002 08:38:00 -0500, Guido van Rossum <guido at python.org> wrote:
> >Tim must be missing something.  The obvious way to turn a bool b into
> >an int is int(b).
> 
> Will this work on old versions of python? I've just checked that it 
> works on 2.0, but what about 1.5.1 or 1.6?
> 
> I'd guess (b*1) would work on everything, however.

The way Guido meant this is really "turn a *bool* into an int". There
are no bools in 2.0, so I wonder what you've checked. If you want to
change an arbitrary object into 0/1, int() certainly won't work:

>>> int([])
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: object can't be converted to int

To turn an arbitrary object into a bool, you could have used
operator.truth so far, since Python 1.4. To turn that into 0/1 pair,
you could write int(operator.truth(obj)). This will also work back to
Python 1.4, since truth already returns 0/1; passing that to int() was
always allowed.

Regards,
Martin