[Python-ideas] Revisiting dedicated overloadable boolean operators

[Chris Angelico]

On Sun, Aug 5, 2018 at 4:40 AM, Todd <toddrjen at gmail.com> wrote:
>
>
> On Sat, Aug 4, 2018 at 9:13 AM, Steven D'Aprano <steve at pearwood.info> wrote:
>>
>> On Fri, Aug 03, 2018 at 03:17:42PM -0400, Todd wrote:
>>
>> > Boolean operators like the sort I am discussing have been a standard
>> > part
>> > of programming languages since forever.  In fact, they are the basic
>> > operations on which modern microprocessors are built.
>> >
>> > The fact that Python, strictly speaking, doesn't have them is extremely
>> > unusual for a programming language.
>>
>> I'm rather surprised at this claim.
>>
>> Can you give a survey of such overridable boolean operators which are
>> available on modern microprocessors?
>>
>> What programming languages already have them? When you say "forever",
>> are you going back to Fortran in the 1950s?
>
>
> Sorry I wasn't clear, I didn't mean overloadable boolean operators are
> standard, but rather boolean operators in general.  I was trying to point
> out that there is nothing domain-specific about boolean operators.

You say that Python doesn't have them. What aspect of boolean
operators doesn't Python have?

> I am personally very strongly against custom operators.  I just have visions
> of someone not liking how addition works for some particular class and
> deciding implementing a "＋" operator would be a great idea.

Eww. (Before anyone jumps in and says "uhh you already have __add__",
that is *not* U+002B PLUS SIGN, it is U+FF0B FULLWIDTH PLUS SIGN,
which would indeed be a custom operator.)

But ultimately, there is already nothing stopping people from doing this:

def Ien(obj):
    """Return object size in machine words"""
    return sys.getsizeof(obj) // (sys.maxsize.bit_length() + 1)

and mixing and matching that with the built-in len function. Give
people freedom, and some will abuse it horrifically... but others will
use it usefully and safely.

ChrisA