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To: internals <internals@lists.php.net>
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Date: Mon, 8 Aug 2016 18:54:04 +0100
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Subject: Re: [PHP-DEV] Function auto-loading
From: rowan.collins@gmail.com (Rowan Collins)

On 08/08/2016 18:03, Levi Morrison wrote:
>     If not, I don't see why we ever need to be able to autoload global
>     functions. "You want autoloading? Put it in a namespace." Like I
>     say, that leaves the very small edge case of a single namespace
>     spanning multiple files, and an autoloader implementation able to
>     include one of them when a function is called from another.
>
>
> I'm not sure why you would think a single namespace spanning multiple
> files is a "very small edge case". I disagree. Here are some libraries I
> am aware of *off the top of my head* that use functions the same
> namespace across multiple files:
>
>   * https://github.com/nikic/iter
>   * https://github.com/lstrojny/functional-php
>
> As well as several of my personal projects. I do not think this is a
> "very small edge case."

The "iter" example looks a long way from being autoloadable whatever we 
supported, but the example of one-function-per-file is definitely 
relevant, so I stand corrected.

After a bit of clicking, I even managed to find a line which would fail 
to autoload under the proposed limitation:

https://github.com/lstrojny/functional-php/blob/master/src/Functional/CompareObjectHashOn.php

 > return compare_on($comparison, $keyFunction);

Although interestingly, at the top of the file there is a (technically 
unnecessary) "use function Functional\compose;" If there was a "use 
function Functional\compare_on;" as well, we'd be fine. (The function 
name would then become qualified at compile time and trigger autoloading 
at run time.)


On 08/08/2016 18:06, Rasmus Schultz wrote:
 > Unless there's a demonstrated, critical performance issue with
 > auto-loading of global functions, please, let's not cripple this feature
 > with inconsistencies from the get-go!

Sure, we could try to measure it, but remember that it's not just the 
engine code that has the extra cost, it will actually call a userland 
function every time you use a global function from inside a namespace if 
you don't add a leading "\". That userland function will probably do a 
bunch of string comparisons before deciding it's not interested, and may 
even try to stat a file or two. Those are really expensive operations, 
so I think it's a long way from "micro-optimisation".

Unfortunately, function name resolution has this quirk that class name 
resolution doesn't, so something's got to give.

Regards,
-- 
Rowan Collins
[IMSoP]