I like the idea - getting away from the mess that __get
and __set
can introduce is a great goal, but this example is confusing and appears to be incomplete. I checked the RFC for more details, and the number of different forms this could take just made me even more confused. Why do we need multiple variants and combinations of shorthand and magic variables, when it's ultimately just defining a special use case function? I'd be much happier with a simple keyword added to a normal function definition to denote it's purpose.
This kind of code looks very appealing when performing very simple (and anemic) CRUD operations on a model, but it has a very short trajectory when the code gets a little more complex.
Triggering events is shown as an example of an advantage of this feature, but it's clearly a bad idea: https://3v4l.org/ZCVpG#v8.2.11
Also, if you need a centralized validation around an attribute, a value object is a way better option: https://3v4l.org/QWm8c#v8.2.11
I think that there are a ton of better requests with a lot more of value to achieve this in userland code.
Also, this idea is very overlooked, and would require a lot of internals work after to cover all the edge cases. How should child classes behave? Are they overridable? How do you know if there is a setter behavior defined already? How should traits behave? Is there a way to call the parent class setter/getter? Would that be overriden or just called by default?
Also, in response to some comments:
It could be used by ORMs like Laravel Eloquent Model that has cast and other hooks to transform data on get/set.
Good ORMs should provide mechanisms for this!
However, I actually often find the need for more fine-grained control over input and output, but adding methods feels so heavy-weight.
This is the perfect case for value objects to kick in. You want behavior (input validation, output transformation maybe) at an atomic member, that could be exactly this but atomically standalone, and therefore reusable in other cases, and very easily testable.
While I'm not against the concept in general, this implementation is not well-done. The $value variables comes from nowhere and makes it confusing - it looks like an undefined variable and a quick glance at it, was the first thing I thought - where is $value coming from? Why not just use $name within that block? Same with $field? Why not just return the value that is going to be set? This is one of the more confusing RFCs I've seen and does not follow the PHP-code style, makes things confusing for both new and experienced coders. In it's current format, I can't approve with good conscience.
In my opinion the solution as is proposed is ambigious because you would have to guess the variable names and these variables by themselfs only suggest their functionality. Like other langauge constructs which have specific keywords or syntax. The concept I support but this variant I do not.
With First-class callable syntax available since 8.1, it would now be possible to write it as below, which is much better then string names of functions:
$result = "Hello World" |> htmlentities(...) |> str_split(...) |> fn($x) => array_map(strtoupper(...), $x) |> fn($x) => array_filter($x, fn($v) => $v != 'O');
The 'use' statement clarifies the scope for me. So a proposal like this could have the side effect of mixing scope which would lead to a confusing code.
I'm not sure if allowing default implementations in interfaces is the way to go here.
To me it looks like a workaround / hack for non existing multi inheritance.
Why not either make multi inheritance possible instead or allow traits with interfaces as suggested by Victor?