On Thu, 22 Jan 2026, Tim Düsterhus wrote:
> Arnaud and I would like to start discussion on our RFC “Partial Function
> Application for instance of non-static methods ("$this")” which is intended to
> round-off the Partial Function Application RFC that was accepted recently:
>
> https://wiki.php.net/rfc/partial_function_application_this
We propose allowing a named parameter $this: ? to be combined with the
“scope resolution operator” syntax of referring to a method.
I can't say I am entirely sold on the syntax here — starting with a $
makes it look like a variable.
Since the $this: ? parameter does not refer to a parameter in
the underlying argument list and thus there is no ambiguity with
regard to positional parameters it may be placed at any position
of the parameter list
I think I would be keen on *requiring* this to be the **first** in the
argument list.
Although there is no ambiguity, I also can't see why you would want to
have it anywhere else.
And the RFC does acknowledge "instance methods which effectively carry
an implicit $this parameter that is provided on the left side of the ->
operator."
With both these two above comments, I think I would like to see a better
syntax — but I am unsure if that's possible.
It may also not be used when partially applying an instance
method with a known object.
$c = $dateTime->format($this: ?, "c"); // Fatal error: Invalid use of
$this placeholder
Can you explain (in the RFC) what you mean by "known object" — I don't
think the language on what this means is clear enough.
cheers,
Derick
