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Subject: Re: [PHP-DEV] [RFC] Skipping parameters take 2
From: dev@mabe.berlin (Marc Bennewitz)


Am 19.01.2015 um 19:48 schrieb Adam Harvey:
> On 17 January 2015 at 18:04, Andrea Faulds <ajf@ajf.me> wrote:
>> For consistency with list(), we could also just put nothing:
>>
>>
>>      foo($bar, , $baz);
>>
>> Which is like:
>>
>>      list($bar, , $baz) = $arr;
>>
>> Thoughts?
> That was Stas's original, original proposal way back when. I argued
> then for having "default" as a placeholder, and still would today — in
> the case where a function with, say, ten optional parameters[0] is
> being called and eight of them should be the default, I think it's a
> bit rough for somebody inheriting that code to have to count commas.
> Having a token increases readability, IMO, and costs us nothing except
> a few keystrokes, which isn't going to break the camel's back in a
> language that requires "function" each time you declare a function.
>
> Adam
>
> [0] Yes, that's probably poor API design. You and I both know someone
> will do it, though. :)

Pros & Cons

_Simply skipping the argument out:_
pro:
     - same syntax as skipping entries used by `list`
con:
     - hard to read and to differ from mistakes
     - not an option for inheritance

_Using the keyword `default`:_
pro:
     - better to read and to differ from mistakes
     - usable on inheritance
con:
     - different syntax as `list`
     - not possible as alternative syntax for `list` as it has no 
"default" naming

_Using a special character:_
pro:
     - better to read and to differ from mistakes
     - usable on inheritance
     - possibly an alternative syntax for `list` (for consistency)
con:
     - different syntax as `list`
     - Not a good character found for it, yet

_Named Parameters:_
pro:
     - readability  (If caller is not required to call as assoc array)
     - not an option for inheritance
con:
     - paramter skipping is a side product with possible edge cases
     - Adds variable names to be part of the API
     - implementation complexity

In my opinion plain skipping parameters is a nice addition to PHP even 
if named arguments will be introduced.

A special character would indeed the best option but as long as there is 
no good character it's not an option.

@Stas: Any news on using default on inheritance ?

Marc