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Date: Sun, 30 Aug 2020 02:31:35 -0400
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Cc: PHP internals <internals@lists.php.net>
To: tyson andre <tysonandre775@hotmail.com>
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Subject: Re: [PHP-DEV] Proposal: Adding functions any(iterable $input,
 ?callable $cb = null, int $use_flags=0) and all(...)
From: mike@newclarity.net (Mike Schinkel)

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> On Aug 29, 2020, at 7:18 PM, tyson andre <tysonandre775@hotmail.com> =
wrote:
>=20
> Hi Alex,
>=20
>> I like it!=20
>>=20
>> What is the $use_flags parameter for?
>=20
> It's for deciding what parameters to pass to callback, like =
https://www.php.net/array_filter - the reflection name should probably =
just be $flag
>=20
> Occasionally, the key might be useful to check against, e.g. the =
identifier of an item in a map, or SplObjectStorage.
>=20
> - the default is `any($iterable, fn ($value) =3D> ...)`
> - or `any($iterable, fn ($key) =3D> expr, ARRAY_FILTER_USE_KEY)`
> - or `any($iterable, fn ($value, $key) =3D> expr, =
ARRAY_FILTER_USE_BOTH)`

Doesn't the occasional required use of long constant names like =
ARRAY_FILTER_USE_KEY and ARRAY_FILTER_USE_BOTH somewhat negative the =
benefit of a more concise syntax? =20

I know that many existing functions in PHP have a collection of long =
constant names that can be passed, but is that a style of programming =
that PHP really wants to continue to proliferate, or would it not be =
better to address that use-case in a different manner?   (Admittedly =
doing so might require having this feature dependent on other critical =
path language features.)

One approach might be if PHP could allow for skipped parameters in =
callables =E2=80=94 where I am using a single underscore to indicate an =
unused parameter (GoLang has a "blank identifier" for similar purposes =
so there is some prior art to consider) =E2=80=94 e.g:

- the default is `any($iterable, fn ( $value ) =3D> ...)`
- or `any($iterable, fn ( _, $key ) =3D> expr )`
- or `any($iterable, fn ( $value, $key ) =3D> expr )`

PHP could handle it more generically, is possible, or recognize this and =
branch to different implementations of any() and all() if the goal is to =
optimize performance by only passing one value in key-only or value-only =
calls.

Optionally we could use null instead:

- the default is `any($iterable, fn ($value) =3D> ...)`
- or `any($iterable, fn (null, $key) =3D> expr )`
- or `any($iterable, fn ($value, $key) =3D> expr )`

-Mike

[1] =
https://www.geeksforgeeks.org/what-is-blank-identifierunderscore-in-golang=
/#:~:text=3D_(underscore)%20in%20Golang%20is,Blank%20Identifier. =
<https://www.geeksforgeeks.org/what-is-blank-identifierunderscore-in-golan=
g/#:~:text=3D_(underscore)%20in%20Golang%20is,Blank%20Identifier.>=

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