The slash "/" as used in the documentation

Ian Kelly ian.g.kelly at gmail.com
Mon Feb 11 15:52:24 EST 2019


On Mon, Feb 11, 2019 at 1:35 PM Chris Angelico <rosuav at gmail.com> wrote:
>
> On Tue, Feb 12, 2019 at 7:26 AM Avi Gross <avigross at verizon.net> wrote:
> > If you want to talk about recent or planned changes, fine. But make that
> > clear. I was talking about how in the past positional arguments did not have
> > defaults available at the def statement level. I was talking about how use
> > of the symbol "=" in the context of defining function parameters had
> > multiple meanings. It not only established that the parameter accepted a
> > keyword but also provided a default.
>
> When was this the case? Positional arguments with defaults is a
> concept known in MANY languages, including C. The equals sign has
> nothing to do with keyword arguments.
>
> Calling on the D'Aprano Collection of Ancient Pythons for confirmation
> here, but I strongly suspect that positional arguments with defaults
> go back all the way to 1.x.

The archived documentation shows that both parameter defaults and
keyword arguments have been around since at least 1.4. I can't
directly confirm that required parameters could be passed by keyword,
but I see nothing in there that says they can't, or that appears to
conflate parameters having defaults with keyword arguments, which is
as one would expect -- whether an argument is passed positionally or
by keyword is a property of the function *call* expression, whereas
whether a parameter has a default or not is a property of the function
*definition*. They happen to both use the = symbol followed by an
expression, but in different syntactical environments, and that is the
only correlation between them.


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