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Date: Tue, 7 Jul 2020 21:24:39 +0100
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Subject: Re: [PHP-DEV] Proposal: A way for classes to define a response to any
 primitive type cast
From: rowan.collins@gmail.com (Rowan Tommins)

On 07/07/2020 18:13, Josh Bruce wrote:
> Decided to put something together:https://github.com/joshbruce/external-project-proposals/blob/master/php-concepts/interact-with-instance-as-php.md


Hi Josh,

Reading through this, it seems to cover a few different concepts, which 
are certainly related, but not quite the same.

Firstly, we have interfaces such as Countable and Serializable, which 
don't make the object act like any particular primitive type, they just 
customise its interaction with particular functions. Iterators could 
potentially be included in that category, too, because it's fairly easy 
to imagine the language having multiple primitive types that can be 
iterated (e.g. separate "list" and "dictionary" types).

ArrayAccess feels more explicitly about making an object "act like" an 
array, but more precisely it overloads the [] operator - it doesn't 
allow the object to be used in other contexts where arrays are allowed. 
More general operator overloading was discussed recently, and the 
particular proposal put forward did not pass its RFC vote. [1]

  __toString, on the other hand, only allows the object to be *converted 
to* a string, not act like one. You can't, for instance, influence the 
behaviour of the concatenation operator, and make "Hello" . $object . 
"!" return an object instead of a string, or a string that doesn't begin 
"Hello". An __toArray method was proposed recently, to mixed reaction. [2]

The other closely related topic is what is often discussed as "scalar 
methods" or "scalar objects" - the ability to call methods on non-object 
values, and possibly to define your own methods that can be called in 
this way. This would seem to fit your use case with Shoop quite well: 
rather than Shoop::array($array)->first()->unfold(), you would just call 
$array->first(). It's fairly high on a lot of people's wish lists, but 
there's a lot of details to get right in both design and implementation, 
so I strongly recommend searching for previous discussions and proofs of 
concept before diving in.


[1] https://wiki.php.net/rfc/userspace_operator_overloading
[2] https://externals.io/message/105589

-- 
Rowan Tommins (né Collins)
[IMSoP]