Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info>:
> Marko Rauhamaa wrote:
>> I prefer the Scheme way:
>> #f is a falsey object
>> everything else is a truthy object
>
> The Scheme way has no underlying model of what truthiness represents, just
> an arbitrary choice to make a single value have one truthiness, and
> everything else the other. It's just as meaningless and just as arbitrary
> as the opposite would be:
>
> #t is True
> everything else is falsey
> [...]
> I'd rather the Pascal way:
>
> #t is True
> #f is False
> everything else is an error
An advantage of the Scheme way is the chaining of "and" and "or". For
example, this breaks in Python:
def dir_contents(path):
if os.path.isdir(path):
return os.listdir(path)
return None
def get_choices():
return dir_contents(PRIMARY) or \
dir_contents(SECONDARY) or \
[ BUILTIN_PATH ]
Marko
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