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Date: Thu, 19 Jan 2017 17:59:59 -0700
Message-ID: <CAFMT4NqbvxzSB8=+3RT87oC0QfLEbtNH8ip7XGmYxtnd5h8dFA@mail.gmail.com>
To: Ryan Pallas <derokorian@gmail.com>
Cc: Rowan Collins <rowan.collins@gmail.com>, 
	"internals@lists.php.net" <internals@lists.php.net>
Content-Type: text/plain; charset=UTF-8
Subject: Re: [PHP-DEV] Pipe Operator v2
From: levim@php.net (Levi Morrison)

On Thu, Jan 19, 2017 at 4:55 PM, Ryan Pallas <derokorian@gmail.com> wrote:
> On Thu, Jan 19, 2017 at 4:08 PM, Rowan Collins <rowan.collins@gmail.com>
> wrote:
>>
>>
>> On 19/01/2017 22:17, Ryan Pallas wrote:
>>
>>>
>>> When you say assert the right hand side is callable, does that mean to
>>> call an object method, you would do [$obj, 'method']? What about
>>> functions,
>>> is it just the name like $str |> trim, or is it $str |> trim()?
>>>
>>
>> This is a good point. The difference between the pipe operator as proposed
>> by Sara and the combination of two separate operators is that in Sara's
>> proposal you'd always write this:
>>
>> $str |> trim($$)
>>
>> But in Levi's proposal as I understand it, the right-hand side is not
>> syntax, it's just constrained to be callable, so the simpler (but rather
>> ugly) form would be:
>>
>> $str |> 'trim'
>>
>
> See I don't like that at all, I hate having to put functions/methods in
> strings, as find usages and refactor tools generally don't find the
> strings. But sometimes I have to yield my preference to those who outrank
> me (aka those with voting power)

While this would be permitted:

    $str |> 'trim'

So would:

    $str |> trim($$)

I empathize that you don't like string-name callables (I really don't
like them either) but this RFC helps avoid the string if you want to.
Consider

    // without my proposal:
    array_map('trim', $input)

    // with it:
    array_map(trim($$), $input)

Which makes a bigger difference for namespaced functions:

    // without my proposal:
    array_map('namespaced\func\map', $input)

    // with it (assuming you are in the correct namespace or
    // did `use function namespaced\func\map`:
    array_map(map($$), $input)

So to summarize, the right-hand-side of `|>` being callable doesn't
mean you "have to" put it in a string; you can pair it with `$$` to
avoid that.