Operator Precedence/Boolean Logic

Marko Rauhamaa marko at pacujo.net
Thu Jun 23 04:16:50 EDT 2016


Antoon Pardon <antoon.pardon at rece.vub.ac.be>:

> It is why I have sometime found the need to write:
>
>     if flag is True:
>
> Because flag needed to be True, not truthy.

Then, you have found the correct idiom for your rare need. You might
even want to consider:

   if flag is UP:
       ...
   elif flag is DOWN:
       ...
   else:
       assert flag is HALFMAST
       ...


I don't particularly like Python's falsey/truthy semantics, but I can
live with it. The biggest problem I have with it is the absence of an
emptiness predicate. I'd like to be able to write:

    if not leftover.empty():
        ...

or even:

    if not empty(leftover):
        ...

rather than having to say:

    if not leftover:
        ...

or:

    if len(leftover) > 0:    # no, I'd never write this
        ...


Marko


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