Boolean tests [was Re: Attack a sacred Python Cow]

[Carl Banks]

On Jul 29, 10:23 pm, Erik Max Francis <m... at alcyone.com> wrote:
> Carl Banks wrote:
> > Bzzt.  "if len(x)!=0" is a simple explicit that would work for this
> > class and all built-in containers. (Or should--Steven D'Aprano's
> > objections notwithstanding, any reasonable container type should
> > support this invariant.  From a language design standpoint, an "empty"
> > builtin could have been created to simplify this even more, but since
> > there isn't one len(x)!=0 will have to do.)
>
> That you choose not to test for non-emptiness doesn't change the fact
> that it's already a builtin part of the language that is supported by
> all fundamental types and is overridable by anyone writing a custom
> type.  Use it or don't use it, but it's an example of precisely what you
> were asking for that is both practical and already in widespread use.

That's not what I was asking for.  I was asking for a use case for "if
x" that can't be replaced by a simple explicit test.  Your example
didn't satisfy that.


Carl Banks