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Reply-To: Levi Morrison <levi.morrison@datadoghq.com>
Date: Mon, 26 Apr 2021 07:42:34 -0600
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To: Lynn <kjarli@gmail.com>
Cc: Larry Garfield <larry@garfieldtech.com>, php internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Partial function application
From: internals@lists.php.net ("Levi Morrison via internals")

> If this is indeed the scenario, would it be worth adding a syntax to
> indicate _all_ parameters can be placeholders? When a signature has
> multiple arguments, `toString(?, ?, ?, ?)` could become `toString(...?)` or
> maybe something like `toString(*)`?

At the moment, there isn't any difference in `foo(?)` and `foo(?, ?,
?, ?, ?, ?, ?, ?)`. If there is one placeholder, then it will bind (or
fix) the non-placeholder arguments and then create a closure-like with
a signature of the remaining parameters. Adding more placeholders does
not change anything, except to adjust positions:

  foo(?, $bar, ?, $baz)

In this case the two placeholders are meaningful because they adjust
which positional arguments are bound. This is the only difference in
behavior in one placeholder or more.

In an earlier version of the RFC I had `...` so you could write
`foo(...)`. Some of the RFC authors didn't like this, because it was
functionally no different and brought up "when to use ? and when to
use ..." as a question.