== What the differences are between Python _bool_s and _int_s

I mentioned in [[the previous entry EqualityDictSurprise]] that Python's
_bool_ class is actually a subclass of _int_ (and the _bool_ docstring
will tell you this if you bother to read it with _help()_ before,
say, diving into the CPython source code like a [[system programmer
../sysadmin/SystemProgrammerDanger]]). Since I was just looking at this,
I might as well write down the low-level differences between _int_s and
_bool_s. Bools have:

* a custom ((__repr__)) that reports _True_ or _False_ instead of the
  numeric value; this is also used as the custom ((__str__)) for
  _bool_.

  (The code is careful to _intern_ these strings so that no matter
  how many times you _repr()_ or _str()_ a boolean, only one copy
  of the literal 'True' or 'False' string will exist.)

* a ((__new__)) that returns either the global _True_ object or the
  global _False_ object depending on the truth value of what it's given.

* custom functions for _&_, _|_, and _^_ that implement boolean algebra
  instead of the standard bitwise operations if both arguments are
  either _True_ or _False_. Note that eg '_True & 1_' results in a
  bitwise operation and an _int_ object, even though _1_ is [[strongly
  equal EqualityDictSurprise]] to _True_.

That's it.

I'm not quite sure how _bool_ blocks being subclassed and I'm not
curious enough right now to work it out. \\
Update: see the comments for the explanation.

The global _True_ and _False_ objects are of course distinct from
what is in effect the global _0_ and _1_ objects that are [[all but
certain ObjectIdentityGotcha]] to exist. This means that their
_id()_ is different (at least in CPython), since the _id()_ is the
memory address of their C-level object _struct_.

(In modern versions of both CPython 2 and CPython 3 it turns out
that global _0_ and _1_ objects are guaranteed to exist, because
'small integers' between -5 and 257 are actually preallocated as
the interpreter is initializing itself.)