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References: <861afae0-4568-745f-6615-a252067cc506@aimeos.com> <003801d5a2df$801404e0$803c0ea0$@jhdxr.com>
In-Reply-To: <003801d5a2df$801404e0$803c0ea0$@jhdxr.com>
Date: Mon, 25 Nov 2019 18:33:20 +0100
Message-ID: <CAH0Uv3Et+U8A=OuR-yN9948DK6=NCxKJC-nVE4pjNTrywpFaOw@mail.gmail.com>
To: CHU Zhaowei <me@jhdxr.com>
Cc: "Aimeos | Norbert Sendetzky" <norbert@aimeos.com>, PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="000000000000918bca05982f29fe"
Subject: Re: [PHP-DEV] [RFC] "arrayable" pseudo type hint
From: andreas@dqxtech.net (Andreas Hennings)

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On Sun, 24 Nov 2019 at 16:55, CHU Zhaowei <me@jhdxr.com> wrote:

> > This proposal is not obsolete by the implementation of union types (i.e.
> > array|Traversable) because union data types are types/interfaces
> > combined by OR. "arrayable" is a combination of OR and AND:
> >
> > array|ArrayAccess&Countable&Traversable
>
> True. But it's also easy to implement in userland. Just create a new
> interface that extends these three interfaces, then union types can work.
>
> ```php
> interface Arrayable extends ArrayAccess, Countable, Traversable {}
>
> function array_x (array|Arrayable $arr) {}
> ```
>
> This is not something that userland cannot implement or very difficult to
> implement. IMO it will make php more complex if we include this in the
> core. Actually what you suggested has been totally covered by the future
> scopes of the union types RFC.


or "intersection types":
https://wiki.php.net/rfc/intersection_types


> If you really want to explore this idea, I think they are worth more
> attention, instead of this specific case.
>
> Regards,
> CHU Zhaowei
>
> > -----Original Message-----
> > From: Aimeos | Norbert Sendetzky <norbert@aimeos.com>
> > Sent: Wednesday, November 20, 2019 6:21 AM
> > To: internals@lists.php.net
> > Subject: [PHP-DEV] [RFC] "arrayable" pseudo type hint
> >
> > Since PHP 7.1, there's the "iterable" pseudo type hint that matches
> "array" or
> > "Traversable".
> >
> > PHP frameworks would profit from support of an "arrayable" pseudo type
> hint
> > that matches "array" and all objects that can be used like arrays.
> >
> > For that, "arrayable" objects have to implement these interfaces:
> > - ArrayAccess
> > - Countable
> > - Traversable (i.e. either Iterator or IteratorAggregate)
> >
> >
> > Implementing "arrayable" pseudo type, we could pass arrays or all
> objects that
> > can be used like arrays to methods and do:
> >
> > function useArrayable( arrayable $arg ) : arrayable {
> >     $cnt = count( $arg );
> >     $value = $arg['key'];
> >     foreach( $arg as $key => $entry );
> >     return $arg;
> > }
> >
> >
> > Best use cases are:
> >
> > - Laravel Collection
> > (
> https://github.com/laravel/framework/blob/6.x/src/Illuminate/Support/Collect
> > ion.php)
> >
> > - Aimeos Map (https://github.com/aimeos/map)
> >
> >
> > No new interface is proposed because we can check if objects implement:
> >
> > ArrayAccess && Countable && Traversable
> >
> >
> > Because "array" !== "arrayable", "arrayable objects will not be accepted
> by
> > array_* functions and all functions that only use "array" as type hint
> for
> > parameters and return types.
> >
> >
> > This proposal is not obsolete by the implementation of union types (i.e.
> > array|Traversable) because union data types are types/interfaces
> > combined by OR. "arrayable" is a combination of OR and AND:
> >
> > array|ArrayAccess&Countable&Traversable
> >
> >
> > Also, "arrayable" won't supersede "iterable" because
> >
> > - "iterable" matches arrays, iterators and generators
> >
> > - "arrayable" matches arrays and objects that can be used like arrays
> >
> >
> > "Can be used like arrays" doesn't include support for empty() because it
> works
> > for empty arrays but not for "arrayable" objects without elements.
> > If possible and requested, this may be addressed by another RFC.
> >
> >
> > As Larry Garfield suggested, this pre-RFC proposes concentrates on the
> > "arrayable" pseudo type only.
> >
> > It does NOT discusses that:
> >
> > - arrayable objects can be converted to arrays (Steven Wade works on an
> RFC
> > for a __toArray() magic function)
> >
> > - ArrayObject or any other arrayable object makes the array_* functions
> less
> > relevant in the future
> >
> > - arrayable objects can be passed to array_* functions in the future
> >
> > --
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> >
>
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