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Date: Mon, 11 Jul 2016 17:33:51 +0200
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To: Rowan Collins <rowan.collins@gmail.com>
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Subject: Re: [PHP-DEV] Cascade Operator (was Re: [PHP-DEV] Proposal for php7
 class method return)
From: ocramius@gmail.com (Marco Pivetta)

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Still interested: what's the actual added value of this sort of operator?

Marco Pivetta

http://twitter.com/Ocramius

http://ocramius.github.com/

On 11 July 2016 at 17:28, Rowan Collins <rowan.collins@gmail.com> wrote:

> On 11/07/2016 16:15, Michael Morris wrote:
>
>> But for that to currently work setSomething must return $this.  A cascade
>> operator would avoid this.  What about =>  ?
>>
>> $a->setSomething('here')=>setSomethingElse('there');
>>
>
> This will be ambiguous with array syntax, e.g.
>
> $foo = [ $a->foo() => bar() ]
>
> could be a call to $a->foo() for the key and to bar() for the value, or
> just a chain ending with the array value $a->bar().
>
> Naming things is hard. Inventing operators is harder. ;)
>
> Also note that it's the *first* call that needs a special operator, in
> order to discard the normal return and substitute the left-hand side,
> otherwise mixed chains become ambiguous and probably horrible to implement
> in the engine:
>
> $foo->bar()->baz()=>bob() // what is $this inside bob() ?
>
>
>
> For this sort of chaining I'd propose, in addition to the cascade operator,
>> the chain operator. This would work like the cascade operator except that
>> the return of the function is implicitly the first parameter of the next
>> argument in the chain. Something like this?
>>
>> $a->add(1, 2):>subtract(3):>add(4); // return 4.
>>
>
> This exact feature was proposed a couple of months ago by Sara Golemon.
> See https://wiki.php.net/rfc/pipe-operator and the accompanying
> discussion http://marc.info/?t=146196088900001&r=4&w=2
>
> As far as I know, it's not been formally withdrawn, so might be
> resurrected in some for for 7.2. It might be interesting to see a cascade
> operator at the same time, but some of the same concerns that came up in
> that discussion will probably apply to any proposal.
>
> Regards,
> --
> Rowan Collins
> [IMSoP]
>
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>

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