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Date: Fri, 14 May 2021 19:20:17 -0500
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To: Larry Garfield <larry@garfieldtech.com>
Subject: Re: [PHP-DEV] [RFC] Partial function application
From: aaron@trowski.com (Aaron Piotrowski)


> On May 14, 2021, at 7:00 PM, Larry Garfield <larry@garfieldtech.com> =
wrote:
>=20
> Is that actually going to come up?  Given that PHP functions (at least =
user-space ones) accept extra trailing arguments and just let them fall =
off, I would *expect* a closure that way to do the same.  Named =
arguments continue that, I believe, by just ignoring any variadic =
arguments that do not match a parameter in the function.  It seems odd =
to go back on that behavior now.

I don't consider forwarding extra arguments an issue. I briefly was =
thinking it might be nice to be explicit about the number of arguments a =
partial would accept, but you convinced me otherwise in R11, so I think =
we're on the same page here.

>=20
> I can't speak for the others, but I could tolerate making "more than =
one extra ? beyond the end of the parameter list is an error", =
potentially, as at that point they're redundant.  But if a function has, =
say, 4 params, then fourParams(1, 3, ?) is a convenient way to say "and =
placeholder everything else".  Especially in dynamic cases like Nicolas =
pointed out, you may not necessarily know how many arguments there are.

With what I proposed in my last email, `fourParams(1, 3, ?)` is =
acceptable, there's nothing superfluous there. At least one ? is needed =
to declare a partial. Similarly, a partial for a no parameter function: =
`$partial =3D functionTakingNoParams(?)`. Or even a partial with args =
bound to all four params: `fourParams(1, 2, 3, 4, ?)`.

What would error is `fourParams(1, 3, ?, ?)`, as the second ? is =
meaningless.

I think you've convinced me that one-for-one matching on ? is =
burdensome, but the above is a happy medium perhaps?

Cheers,
Aaron Piotrowski