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Date: Sun, 25 Dec 2022 06:53:01 +0100
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Subject: Re: [PHP-DEV] Methods which auto-return the class instance
From: tovilo.ilija@gmail.com (Ilija Tovilo)

Hi Daniele

On Fri, Dec 23, 2022 at 1:09 AM joke2k <joke2k@gmail.com> wrote:
>
> Hi folks,
>
> What do you think about having a method which returns the class instance
> `$this` by default only IF its return type is set as `self`?
>
> It is very common for fluent class methods to have a verbose `return
> $this;` ending in their body.

Instead of adding special syntax to make writing fluent accessors
easier, I wonder if something akin to Dart's cascade operator would be
a better approach.

https://dart.dev/guides/language/language-tour#cascade-notation

$foo
   ..setBar('bar')
   ..setBaz('baz');

The syntax is just copied from Dart, there's probably a better fit for
PHP. .. would invoke a method call but discard the return value,
evaluating to the lhs of the method call instead.

With an operator solution one can use fluent method calls on APIs that
aren't specifically designed for it when desired, accessors can become
leaner as return $this is no longer necessary, and it becomes obvious
at call-site that the chained methods are called on the same object.

I'm not sure about syntax or the fact that Dart allows property
assignments in combination with .. as that makes the syntax ambiguous
(or whitespace sensitive), but that wouldn't be necessary for what
you're proposing.

Example of the ambiguity:

$foo
    ..bar = $bar
    ..baz()
// Could be parsed as
$foo..(bar = $bar)..baz()
$foo..bar = ($bar..baz())

An alternative might be a C# style syntax which would make property
assignments unambiguous.

$foo {
    setBar('bar'),
    baz = 'baz',
}

But this is also longer and less readable (to me at least).

Anyway, just my unrefined thoughts. I would not support implicit
`return $this` for self or static. At the very least, the return type
should be $this (which is essentially a sub-type of static) but that
too doesn't seem like an elegant solution to me.

Ilija