Hey,
> Am 31.01.2017 um 11:23 schrieb Michael Wallner <m...@php.net>:
>
> On 31/01/17 05:53, Stephen Reay wrote:
>> Hi Andrea, All,
>>
>>> On 31 Jan 2017, at 08:12, Andrea Faulds <a...@ajf.me> wrote:
>>>
>>> Is it necessary to introduce a new keyword, fn?
>>>
>>> I think you'd get a similar benefit from:
>>>
>>> function($x) => $arr[$x]
>>>
>>> Likewise, is it necessary to restrict auto-capture to the =>
>>> syntax? Couldn't we allow the following?
>>>
>>> function ($x) {
>>> return $arr[$x];
>>> }
>>>
>>
>> I agree that the `fn` keyword isn’t really necessary. I’ve never
>> quite understood how arrow functions with implied returns etc are
>> supposed to make for *more* readable code, but if they’re going to be
>> part of the language please at least keep some consistency with
>> regular closures.
>
> Yes, I also think that keeping the function keyword would be better.
>
>>
>> In the case that regular closures got auto-capture, would a
>> `use($foo, $bar, $baz)` segment on a closure still be honoured (i.e.
>> disable auto-capture), and would it have any impact (positive or
>> negative) on performance/memory usage? After several years of JS
>> closure ‘fun’ I kind of like that with PHP you only inherit the
>> variables you explicitly `use()` in closures.
>
> Wouldn't there be just too many existing closures, which do not use
> `use` but (maybe) expect a clean scope?
The RFC is exclusively proposing single-expression short Closures.
We do NOT want multi-statement short Closures; it is a *feature* that generic
Closures need an "use ($foo, $bar)".
This vastly improves readability and debuggability - it basically tells you
whether the variables inside the code are imported or not. As Stephen Reay
notes:
>> After several years of JS
>> closure ‘fun’ I kind of like that with PHP you only inherit the
>> variables you explicitly `use()` in closures.
So, auto-import for generic Closures definitely isn't an option.
Just on short, single-line Closures there is no benefit to "use ()", as EVERY
variable used in the short Closure is supposed to be an imported variable.
There is no point in forcing the user to distinguish between imported and local
variable here.
Also, using "fn" in favor of "function" has the advantage of less clutter in
one line. Compare
array_map(fn($x) => $x + 1)
to
array_map(function($x) => $x + 1)
The syntactical construction is already pretty clearly showing what's going on.
The "function" keyword itself is already larger than the whole body. It
distracts while reading the actual code.
Additionally, using "fn" is optically highlighting the fact that it's a
short-Closure with auto-import and not a normal Closure with explicit import.
Thanks,
Bob
