Set a flag on the function or a global?

[Steven D'Aprano]

On Tuesday 16 June 2015 10:37, Paul Rubin wrote:

> Steven D'Aprano <steve+comp.lang.python at pearwood.info> writes:
>> Thoughts and feedback? Please vote: a module global, or a flag on the
>> object? Please give reasons, and remember that the function is intended
>> for interactive use.
> 
> Both are bad.  More state to remember, ugh.  Instead have separate entry
> points for filtering or not filtering the dunders.  Something like:
> 
>   edir(obj) = no dunders
>   edir_(obj) = dunders.

I certainly wouldn't call it edir_ but I'd maybe call it edir2 or ddir 
("Dunderless DIR") or just_like_builtin_dir_only_better. <wink>

Normally I would agree with you, as a matter of principle, functions which 
differ only by an argument called as a constant, particular when that 
argument is a flag, should be split into multiple functions.

That is, instead of foo(x, flag=True) and foo(x, flag=False), have foo(x) 
and foo2(x).

One disadvantage of this, though, is that it may not be self-evident which 
function does what. Who remembers the difference between all the os.exec* 
functions? Speaking of which:

py> dir(os, 'exec*')
['execl', 'execle', 'execlp', 'execlpe', 'execv', 'execve', 'execvp', 
'execvpe']


But in this case, because [e]dir is intended to be run interactively, I 
think that the convenience of a single function is more important. Most 
people will set the default setting to whatever they prefer and then 95% of 
the time just use it as given, only occasionally giving the dunders keyword 
argument when they need the opposite setting.

Or at least, that's how *I* use it.

-- 
Steve