seeking deeper (language theory) reason behind Python design choice

[Ian Kelly]

On Thu, May 10, 2018 at 7:10 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Fri, May 11, 2018 at 10:29 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> Chris Angelico <rosuav at gmail.com>:
>>
>>> But for the loop itself, you absolutely CAN write this more logically.
>>> I'll take your second version as a template:
>>>
>>>     def split_cmd(self, cmd):
>>>         args = []
>>>         while (match := self.TERM_PTN.match(cmd)) is not None:
>>>             args.append(match.group('term'))
>>>             if not match.group('sep'):
>>>                 verb = args.pop(0).upper()
>>>                 return verb, args
>>>             cmd = cmd[match.end(0):]
>>>         return None, None
>>>
>>> And, if this is actually a regex, "is not None" is unnecessary:
>>>
>>> while match := self.TERM_PTN.match(cmd):
>>>
>>> Now do you understand what I mean about putting the condition into the
>>> loop header?
>>
>> Thanks, but no thanks. The "while True" idiom beats that one hands down.
>
> Because you're used to it? Or because it's somehow more logical to
> pretend that this is an infinite loop? Explain in more detail.

In what way does "while True" in the general case pretend to be an
infinite loop? The break / return is right there for anyone to see.

Would you also contend that generator functions are wrong because they
pretend to be normal functions?

def totally_not_a_generator(n):
    while True:
        if n % 2 == 0:
            n //= 2
        else:
            n = n * 3 + 1
        stealthily = n
        yield stealthily
        if n == 1:
            return n

py> print(totally_not_a_generator(42))  # Lies!
<generator object totally_not_a_generator at 0x77fe4d78c0f8>