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Date: Tue, 18 May 2021 08:44:39 -0500
To: "php internals" <internals@lists.php.net>
Content-Type: text/plain
Subject: Re: [PHP-DEV] [RFC] Partial function application
From: larry@garfieldtech.com ("Larry Garfield")

On Mon, May 17, 2021, at 11:14 PM, Paul Crovella wrote:
> On Fri, May 14, 2021 at 4:44 PM Aaron Piotrowski <aaron@trowski.com> wrote:
> >
> > My issue is the dual-meaning of ? in the current proposal. In `foo(?, 42)`, the ? represents a single argument, but adding a trailing ? (such as in `foo(?, 42, ?)`) represents any number of arguments. Would it perhaps make sense to make superfluous ? markers an error?
> >
> > foo(?); // Fine, needed to define a partial with no bound args.
> > foo(?, 42); // Ok, binds second arg.
> > foo(?, ?, 42); // Ok, binds third arg.
> > foo(?, 42, ?); // Error, unnecessary placeholder.
> > foo(?, ?); // Error, unnecessary placeholder.
> >
> > The intention here is to keep the syntax unambiguous.
> >
> > foo(?) == foo(?, ?) == foo(?, ?, ?) and so forth is not going to be obvious to everyone, so why allow meaningless and misleading syntax.
> >
> > Cheers,
> > Aaron Piotrowski
> >
> 
> While it's my preference not to use superfluous placeholders they do
> no real harm and I do not feel comfortable imposing this preference on
> others.

User-space functions have always accepted more arguments than they're defined with.  They just get dropped off the end silently, unless you use func_get_args() or variadics.  While I know not everyone likes that "feature", it means that extra trailing ? "arguments" don't feel weird to me.  They just get dropped off the end and we move on with life.  At least that's how I conceptualize them.

--Larry Garfield