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To: Tjerk Anne Meesters <datibbaw@php.net>
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Thread-Topic: [PHP-DEV] Gauging Interest:RFC to add map() function
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Date: Thu, 27 Jun 2013 11:13:38 +0000
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Subject: RE: [PHP-DEV] Gauging Interest:RFC to add map() function
From: Richard.Bradley@softwire.com (Richard Bradley)

> -----Original Message-----
> From: tjerk.meesters@gmail.com [mailto:tjerk.meesters@gmail.com] On Behal=
f Of Tjerk Anne Meesters
> Sent: 27 June 2013 11:24
> To: Sebastian Krebs
> Cc: Florin Patan; Jeremy Curcio; PHP Internals
> Subject: Re: [PHP-DEV] Gauging Interest:RFC to add map() function
>
> On Thu, Jun 27, 2013 at 5:43 PM, Sebastian Krebs <krebs.seb@gmail.com>wro=
te:
>
> >
> >
> >
> > 2013/6/27 Tjerk Anne Meesters <datibbaw@php.net>
> >
> >> On Thu, Jun 27, 2013 at 4:27 PM, Florin Patan <florinpatan@gmail.com>
> >> wrote:
> >>
> >> > On Thu, Jun 27, 2013 at 10:17 AM, Tjerk Anne Meesters
> >> >
> >> > May I kindly ask why all the PHP users would want this function in
> >> > the core?
> >> >
> >>
> >> Are you meaning to ask why would *any* php user want this function in
> >> the core? As with most things, the need of one may be shared among a
> >> critical mass that could swing the balance. In practice though, the
> >> critical mass is usually determined by the internals peeps :)
> >>
> >
> > But this method is _really_ quite special, isn't it? I cannot imagine,
> > that there is "critical mass", that needs this _in core_.
> >
>
> I'm not casting any judgement on its usefulness; I'm merely arguing the
> "why should this be in core? I would never use it." narrative is not cons=
tructive.

It can serve as an indication of which way the he would vote if this came t=
o RFC.
It can give a single data point towards how many people would find this use=
ful.
You did ask what people thought of the proposed method. I don't think you s=
hould simply reject negative answers as "not constructive".

> >> > And as I understand, PHP delegates the math stuff to the underlying
> >> > C implementation so why would it be faster having it in PHP core
> >> > rather that in PHP userland?
> >> >
> >>
> >> Performance is not the only reason why features make it into the
> >> core; it's providing a rich set of built-in features to make the
> >> developer's lives easier, such as the latest password hashing API
> >> which is easy to get wrong or generators that reduce boiler plate
> >> code.
> >
> > You cannot compare language features (generators) with functions. And
> > "security" is always a topic on its own.
> >
>
> I consider new functions as a feature of the language as well, so there's=
 no need to make comparisons.
>
> That said, would you have guessed (without looking at the manual) that PH=
P exposes a
> "hypot($x, $y)" where you could otherwise have written "sqrt($x * $x, $y =
* $y)"?
>
> Okay, it's a translation from <math.h> of course, but it came as a surpri=
se to me :)

There is a good reason to have "hypot" in the C layer -- it is not possible=
 to implement it in PHP correctly (and efficiently), due to overflow concer=
ns.

See http://en.wikipedia.org/wiki/Hypot for a summary.

The same concerns do not apply to this affine transform, which is why it sh=
ould not be in core.

If there were sufficient demand for it, then it might justify a PECL extens=
ion. My impression is that there is not.

Best,



Rich



Richard Bradley
Tel : 020 7485 7500 ext 3230 | Fax : 020 7485 7575

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