[Python-Dev] For review: PEP 285: Adding a bool type (original) (raw)

Guido van Rossum guido@python.org
Fri, 08 Mar 2002 11:50:25 -0500

> def repr(self): > if self: > return "True" > else: > return "False" > > str = repr

I don't like this: it will break too much code since there are already two singletons PyTrue and PyFalse available in Python and these return 1 / 0 resp.

But this is the whole point of introducing a new type rather than simply defining True as 1 and False as 0!

> False = bool(0, create=1) > True = bool(1, create=1)

Please adjust PyTrue and PyFalse (at C level) to be identical to these constants.

Yes, that was the intention.

> Issues > > Because the repr() or str() of a bool value is different from an > int value, some code (e.g. doctest-based unit tests) may fail. > How much of a backwards compatibility problem this will be, I > don't know. If we find this is a real problem, we could add a > command-line option to make False and True aliases for 0 and 1 and > bool an alias for int.

Please, no !

Agreed -- I just mentioned it as a possibility if we find too much problems due to the new repr() and str().

Ideal would be to make bool a subtype of int and True and False two singletons created from 1 and 0 having the bool type: that's simple and backwards compatible.

That's what I am proposing.

One idea for a possible addition:

Add boolean support to the array module so that it becomes possible to create arrays of bits.

That's an entirely separate issue, and would require major hackery to the array module (if you want the bits to be tightly packed, which I assume you do). Let's not mix it up with this.

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