Permitting trailing commas in closure use() declarations

Hi internals,

https://wiki.php.net/rfc/trailing_comma_in_parameter_list mentioned

https://wiki.php.net/rfc/list-syntax-trailing-commas Trailing Commas In List Syntax was a previous proposal to support optional trailing commas in all list-like structures.

Nothing has substantially changed since those RFCs in technical terms, but I think the aforementioned style > for breaking up large parameter lists has become more accepted in the meantime, and features like Constructor Property Promotion are going to increase its use further.

So I'm wondering if anyone's interested in revisiting this:

• It'd be easy to forget that function parameters support trailing commas, but not closure uses, especially if you're new to the language.
• Supporting trailing commas in multi-line declarations would make version control history easier
• if you had a closure for which fn wouldn't work (a list of values and references to use, or a list of statements),
  it'd be convenient to split it up across multiple lines

e.g.

       $incrementing_id = 0;
       return \array_map(static function (array $map) use (
           $function,
           $some_data_structure,
           $some_flag,
           &$incrementing_id,
       ): ReturnType {

+1 for consistency with allowing trailing commas in all places like this.

Cheers,
Ben

On Wed, Jun 24, 2020 at 5:23 PM tyson andre tysonandre775@hotmail.com
wrote:

Hi internals,

https://wiki.php.net/rfc/trailing_comma_in_parameter_list mentioned

https://wiki.php.net/rfc/list-syntax-trailing-commas Trailing Commas In
List Syntax was a previous proposal to support optional trailing commas in
all list-like structures.

Nothing has substantially changed since those RFCs in technical terms,
but I think the aforementioned style > for breaking up large parameter
lists has become more accepted in the meantime, and features like
Constructor Property Promotion are going to increase its use further.

So I'm wondering if anyone's interested in revisiting this:

• It'd be easy to forget that function parameters support trailing commas,
  but not closure uses, especially if you're new to the language.
• Supporting trailing commas in multi-line declarations would make version
  control history easier
• if you had a closure for which fn wouldn't work (a list of values and
  references to use, or a list of statements),
  it'd be convenient to split it up across multiple lines

e.g.

        $incrementing_id = 0;
        return \array_map(static function (array $map) use (
            $function,
            $some_data_structure,
            $some_flag,
            &$incrementing_id,
        ): ReturnType {

Sounds reasonable to me. I thought we had already covered all cases that
are inside (), but apparently not.

I think if there are no objections on list, we can just land this change.
Given how positive the outcome of the "trailing comma in parameter lists"
RFC was this doesn't seem controversial.

Regards,
Nikita