Re: [PHP-DEV] Re: Proposal for a RFC

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May 14, 2019 10:11 rowan.collins@gmail.com (Rowan Collins)
On Mon, 13 May 2019 at 19:55, Steven Wade <stevenwadejr@gmail.com> wrote:

> I'm personally unconvinced of the value of this, and would probably propose > it was blocked by coding standards in my team if it was added, because its > meaning is so ambiguous. > > > That's perfectly reasonable. Do you also block use of casting to a string > with (string) $foo as well? I ask because this proposal is simply on par > with the idea behind string casting for objects. >
I have seen valid uses of __toString(), but I would certainly approach it cautiously. For a complex object, it's not at all obvious if (string)$foo will give you a debug representation, a JSON serialisation, an HTML rendering, etc.
> Most objects do not have a single "natural"/"canonical" array > representation > > > I think the same could be said about "__toString()". But with that, some > classes can be boiled down to a single representation, such as the > Ramsey\Uuid <https://github.com/ramsey/uuid/> package. >
Indeed it could. I think the difference is that a "one-dimensional" object, like a UUID, probably does lend itself to a single canonical string representation. You wouldn't expect it to return XML, or JSON, or any other string format, so (string)$uuid is fairly unambiguous.
> The same is with arrays. You can have a single entity such as person to > where its array representation can be first name, last name, age, race, > gender, email, etc..., >
This is exactly the kind of place I would *not* want a simple toArray() function. Should (array)$person (or $person->toArray()) return ['firstName'=>'Rowan', 'lastName'=>'Collins'], or ['name' => 'Rowan Collins'], or ['name' => ['Rowan', 'Collins']]? What date format should 'dateOfBirth' be formatted to? If 'address' is an object, should that be converted to an object as well, and into what format? The answers to these questions are going to be different in different contexts, and it doesn't make sense for the Person class to determine the "one true array representation" - the only canonical representation is the object itself.
> or you can have a collection of items, to where in that representation as an array, you have control over what information is returned and what
isn't. This is a more reasonable case; given that objects can't completely mimic arrays, I can see value in a custom List class implementing an array cast as a quick "back door" for using existing array functionality.
> As a thought experiment, imagine a similar method which allowed you to > overload (object)$foo. Although (array)$foo tells you slightly more than > that, I'm not convinced it tells you enough that you're not just hiding > meaning behind cute syntax. > > > I'm confused by example, as there's no real need to overload casting to an > object as a class is already an object. Whereas, a class is not already an > array. >
Sure, it's extra vague because "return $this" would be a valid response, but imagine there was something other than objects - structs, or custom resources, or whatever - and there was special syntax to say "give me an object based on this thing". The immediate question would surely be "what object? what are you using it for?" I feel the same way about "give me an array based on this object" - it tells me very little about what you actually want, and why.
> It's not about "cute syntax", it's honestly about providing a simple > clutter free helper for developers to take control over how their classes > are transformed to array representations. >
If it's not recursive, it's just syntactic sugar - which can be fine, if it serves a common use case, but it adds an extra "trick" that readers need to know about. It doesn't let you do anything you can't already - (array)$foo would just be a funny way of spelling $foo->__toArray()
> JsonSerializable actually suffers from similar problems, and is IMO useful > only because it's automatically recursive. I presume the proposed mechanism > would not be, i.e. return [$foo] would not be interpreted as return > [(array)$foo]. > > > You bring up a good point. Could you for a moment pretend like you're > behind this proposal and expand upon this question? If PHP were to have a > __toArray() method, would you see it as being recursive? In your opinion, > how should/would it react? >
A recursive method would certainly have more value, because it actually does something more than translate one syntax to another. On the other hand, the use case that comes to mind is serialization, and we already have more specific methods and systems for that. I guess that's what it comes down to, what *specific* use cases would this feature be intended to help with? Is there some code of your own that inspired you to propose it, or something you've seen publically that would benefit from it? Regards, -- Rowan Collins [IMSoP]
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June 13, 2019 14:23 stevenwadejr@gmail.com (Steven Wade)
Apologies for the super late response:

> A recursive method would certainly have more value, because it actually > does something more than translate one syntax to another. On the other > hand, the use case that comes to mind is serialization, and we already have > more specific methods and systems for that.
How could this new magic method be recursive? If it only works if you manually declare __toArray() in your class, wouldn't you then as the user be in charge of casting anything manually in your method implementation?
> > I guess that's what it comes down to, what *specific* use cases would this > feature be intended to help with? Is there some code of your own that > inspired you to propose it, or something you've seen publically that would > benefit from it?
Originally, it was inspired by seeing Laravel's use of Arrayable as an interface and if something implements that, calling that class' `toArray()` method, and wishing that was built in so that frameworks didn't re-invent the wheel every time. As far as in my code, collections being cast as an array easily would be nice. Models with relationships, being able to implement that cast and control how your model and its children are (or aren't) represented. That's useful for returning an array in a controller for an API, or for simply adding context to a log message. IMO, the point is, it's another tool in the developers arsenal that they can use when they see fit. Not everyone will use it and not everyone will see the benefit of it, and that's ok, but for those that would and could, __toArray() is for them (and me). -- Steven Wade stevenwadejr@gmail.com
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June 13, 2019 14:35 ocramius@gmail.com (Marco Pivetta)
On Thu, Jun 13, 2019 at 4:23 PM Steven Wade <stevenwadejr@gmail.com> wrote:

> > I guess that's what it comes down to, what *specific* use cases would > this > > feature be intended to help with? Is there some code of your own that > > inspired you to propose it, or something you've seen publically that > would > > benefit from it? > > Originally, it was inspired by seeing Laravel's use of Arrayable as an > interface and if something implements that, calling that class' `toArray()` > method, and wishing that was built in so that frameworks didn't re-invent > the wheel every time. >
Interestingly, my work day today is spent mostly removing this kind of behavior from a codebase riddled by it, replacing it with explicit conversions where needed. Marco Pivetta http://twitter.com/Ocramius http://ocramius.github.com/