Mike Orr wrote:
> On 1/1/07, Guido van Rossum <[EMAIL PROTECTED]> wrote:
>> On 1/1/07, James Thiele <[EMAIL PROTECTED]> wrote:
>>> PEP 3100 states:
>>> None becomes a keyword [4] (What about True, False?)
>>>
>>> Has a decision been made?
>> No, but I think the argument for making True/False reserved words is
>> pretty weak.
>>
>>> Also a bool acts like an int in various contexts. For example:
>>>>>> True == 1
>>> True
>>>>>> False == 0
>>> True
>>>>>> 16 + (0 == 0)
>>> 17
>>>
>>> Will this behavior continue?
>> Yes. Don't confuse Python with Java.
>
> Huh? 'True == 1' is a "feature"? '16 + (0 == 0)' being illegal is a
> "Javaism"? Would somebody care to explain this? It's acceptable that
> 2 is true but not True? Why do we need 1 for True at all if we have
> True?
None of the above examples are inconsistent with boolean algebra combined with
pythons practice of promoting types in various situations. Since bool is a
subclass of int, it doesn't need promoting to int in these cases, but the
results would be the same.
http://www.allaboutcircuits.com/vol_4/chpt_7/2.html
The only place (I know of) where it seems out of order would be examples like...
>>> True + True
2
>>> True == (True + True)
False
Here the result of the addition two bools is an int instead of being a bool.
The AbstractBaseClass wiki has questions concerning where bool is in the class
tree. It shows bool as *not* being a subclass of int.
http://wiki.python.org/moin/AbstractBaseClasses
So would adding two bools return an int or a bool if this is changed?
Should Bool be a subclass of Numeric instead of object?
The way python uses bools makes me think maybe the relationship between
integers
and bools should be reversed. An integer could be a subclass of bool. Then
all
positive integers, would also be equal to True. But that would change the
behavior of adding integers and bools, because the result would be either a
True
or False instead of an int because the int would be promoted to bool instead of
the bool being (like promoted to) an int.
Cheers,
Ron
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