Imagine reviewing Python code that looks something like this.<\/p>\n
has_items = items is not None and len(items) > 0\nif has_items:\n ...\n\n...\ndo_stuff(has_items=has_items)<\/code><\/pre>\nYou might look at the conditional, and disapprove: None<\/code> and empty collections are both falsey, so there's no reason to define that has_items<\/code> variable; you could just say if items:<\/code>.<\/p>\nBut, wouldn't it be weird for do_stuff<\/code>'s has_items<\/code> kwarg to take a collection rather than a boolean? I think it would be weird: even if the function's internals can probably<\/em> rely on mere truthiness rather than needing an actual boolean type for some reason, why leave it to chance?<\/p>\nSo, maybe<\/em> it's okay to define the has_items<\/code> variable for the sake of the function kwarg\u2014and, having done so anyway, to use it as an if<\/code> condition.<\/p>\nYou might object further: but, but, None<\/code> and the empty collection are still both falsey<\/em>. Even if we've somehow been conned into defining a whole variable, shouldn't we say has_items = bool(items)<\/code> rather than spelling out is not None and len(items) > 0<\/code> like some rube<\/em> (or Rubyist)<\/a> who doesn't know Python?!<\/p>\nActually\u2014maybe not. Much of Python's seductive charm comes from its friendly readability (\"executable pseudocode\"): it's intuitive<\/em> for if not items<\/code> to mean \"if items<\/code> is empty\". English, and not the formal truthiness rules, are all ye need to know. In contrast, it's only if you already<\/em> know the rules that bool(items)<\/code> becomes meaningful. Since we care about good code and don't care about testing the reader's Python knowledge, spelling out items is not None and len(items) > 0<\/code> is very arguably the right thing to do<\/em> here.<\/p>\n","protected":false},"excerpt":{"rendered":"Imagine reviewing Python code that looks something like this. has_items = items is not None and len(items) > 0 if has_items: ... ... do_stuff(has_items=has_items) You might look at the conditional, and disapprove: None and empty collections are both falsey, so … Continue reading