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Date: Wed, 12 Feb 2014 02:52:29 +1100
Subject: Re: PyWart: More surpises via "implict conversion to boolean" (and other steaming piles!)
From: Chris Angelico <rosuav@gmail.com>
Cc: "python-list@python.org" <python-list@python.org>
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On Wed, Feb 12, 2014 at 2:36 AM, Travis Griggs <travisgriggs@gmail.com> wro=
te:
> OTOH, I=E2=80=99m not sure I=E2=80=99ve heard the parameters-less functio=
ns are a code one? Is it just loose functions that you=E2=80=99re referring=
 to? As opposed to methods (which are just bound functions)? I could maybe =
accept that. But methods with fewer arguments, and even none, are a desirab=
le thing. There are code smells that are the opposite in fact, methods with=
 long parameter lists are generally seen as code smell (=E2=80=9Cpassing a =
paragraph=E2=80=9D).
>

'self' is, imo, a parameter. When you call a parameter-less method on
an object, it's usually an imperative with a direct object (or
sometimes a subject):

some_file.close() # "Close some_file"
some_list.shuffle() # "Shuffle some_list"
some_file.readline() # "Some_file, read in a line"

There are times when, for convenience, the object is implicit.

print("some text", file=3Dsome_file) # Print that text
print(file=3Dsome_file) # Print a blank line
print("some text") # Print that text to sys.stdout
print() # Print a blank line to sys.stdout

So in that situation, the no-args call does make sense. Of course,
this is a call to a function that does take args, but it's accepting
all the defaults and providing no additional content. It's quite
different to actually define a function that mandates exactly zero
arguments, and isn't making use of some form of implicit state (eg a
closure, or maybe a module-level function that manipulates
module-level state - random.random() would be an example of the
latter). Syntactically, Python can't tell the difference between
"print()" and "foo()" where foo can never take args.

I'd say that a function taking no args is code smell, unless it's
obviously taking its state from somewhere else (callbacks, for
instance - maybe you pass a bound method, or maybe a closure, but in
either case it has implicit state that's not described by function
args); but _calling_ with no args isn't as smelly. It's certainly less
common than using args, but there are plenty of times when a type is
called without args, for instance[1].

ChrisA

[1] Okay, that was a really abysmal pun.