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Date: Mon, 2 Feb 2015 07:45:55 +1100
Subject: Re: dunder-docs (was Python is DOOMED! Again!)
From: Chris Angelico <rosuav@gmail.com>
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Xref: csiph.com comp.lang.python:85028

On Sun, Feb 1, 2015 at 4:36 PM, Rustom Mody <rustompmody@gmail.com> wrote:
> The other day I was taking a class in which I was showing
> - introspection for discovering -- help, type, dir etc at the repl
> - mapping of surface syntax to internals eg. a + b =E2=86=90=E2=86=92 a._=
_add__(b)
>
> And a student asked me the diff between
> dir([])
> and
> [].__dir__()
>
> I didnt know what to say...

Simple answer: You write dunder methods and the interpreter calls
them. You don't call them yourself.

I can't currently think of any situation where it's appropriate to
call a dunder method manually (cue the swamping of such situations on
the list); you just call dir() or the + operator or whatever it be.

ChrisA