On Thu, Sep 21, 2017 at 3:13 PM, Stanislav Malyshev <smalys...@gmail.com> wrote:
> Hi!
>
>> After discussion with Levi and others who suggested a simpler
>> approach, I'd like to offer
>> https://github.com/php/php-src/compare/master...sgolemon:pipe2 as an
>> alternate possibility.
>
> I am still feeling it is a bit weird to do things that way, but other
> than that (which is just my personal issue) I do not see any problems in
> this proposal. With magic weird $$ thing gone, it seems to be
> straightforward and mostly intuitive. So while I am not feeling this is
> a must, I think it may be nice to have it.
>
> It'd be also nice then if we could have some syntax that allowed us to
> refer to functions/methods as callables - mostly for the benefit of the
> code readers and IDEs. I.e. you can do "hello" |> "strtoupper" and it's
> fine but it is not at all intuitive what you're doing sending one string
> into another. Same with "hello" |> [$this, 'bar']. Now, if we could do
> something like this:
> "hello" |> &{strtoupper}
> "hello" |> &{$this->bar}
>
> (yes I know the syntax is ugly, I hope you get the idea though to have a
> syntax for this) then you could have better readability, easier IDE
> autocompletion and other benefits. Not for this RFC, clearly, but just
> putting it out there so I don't forget.
>
> --
> Stas Malyshev
> smalys...@gmail.com
>
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I don't want to get too far off topic but since Stas has wandered off
a bit already I'll mention this. Scala has "placeholders":
val sum = List(1,2,3,4,5).reduceLeft(_+_)
The expression `_ + _` will create a function that takes two
parameters and then returns the result of adding them together,
equivalent to this:
val sum = List(1,2,3,4,5).reduceLeft((a, b) => a + b)
The single underscore `_` might not work for PHP because `gettext` has
used a single underscore as an alias for... a long time, maybe since
its inception. But for this example I'll use it anyway:
"hello" |> strtoupper(_) |> $this->bar(_)
It's saying, pretty literally, fill in the blank. Remember, though,
it's actually creating closures and doesn't directly mean "put the
result of the left-hand side here" unlike the previous proposal for
`$$`.
I brought it up because this can fill the same need as Stas' proposal
creating callables with something like `&{strtoupper}`. If we used
the symbol `$$` for the same placeholder mechanism from Scala it
becomes a more general purpose mechanism that could be used for any
callables, not just ones involved in a pipe:
$potentially_valid_emails =
array_filter($this->isProperlyFormattedEmailAddress($$), $email_list);
Anyway, the purpose of this thread is to talk about the pipe operator
so I'll stop talking now.
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