Re: Cascade Operator (was Re: [PHP-DEV] Proposal for php7 class method return)

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and the accompanying discussion http://marc.info/?t=146196088900001&r=4&w=2 As far as I know, it's not been formally withdrawn, so might be resurrected in some for for 7.2.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]