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Date: Fri, 25 Sep 2015 07:49:58 +0900
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To: Anatol Belski <anatol.php@belski.net>
Cc: Kalle Sommer Nielsen <kalle@php.net>, Ferenc Kovacs <tyra3l@gmail.com>, 
	"internals@lists.php.net" <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Re: [RFC] [DISCUSSION] More precise float value
From: yohgaki@ohgaki.net (Yasuo Ohgaki)

Hi Anatol,

On Tue, Sep 22, 2015 at 4:35 AM, Anatol Belski <anatol.php@belski.net> wrot=
e:
>> -----Original Message-----
>> From: yohgaki@gmail.com [mailto:yohgaki@gmail.com] On Behalf Of Yasuo
>> Ohgaki
>> Sent: Sunday, September 20, 2015 11:49 PM
>> To: Kalle Sommer Nielsen <kalle@php.net>
>> Cc: Anatoliy Belsky <ab@php.net>; Ferenc Kovacs <tyra3l@gmail.com>;
>> internals@lists.php.net
>> Subject: Re: [PHP-DEV] Re: [RFC] [DISCUSSION] More precise float value
>>
>> Hi Anatol and Ferenc,
>>
>> On Sat, Sep 19, 2015 at 7:15 AM, Kalle Sommer Nielsen <kalle@php.net> wr=
ote:
>> > I'm sorry I have not caught this any earlier, but even without
>> > consulting with Anatol, I'm not keen on adding this into 7.0, we are
>> > in RC stage, and I want us to focus on a stable release instead of
>> > adding more potential issues, I suggest you target 7.1 instead in the
>> > RFC.
>> >
>> > (Ferenc and Anatol cc'd)
>>
>> I was expecting this kind of reply for this RFC.
>> What do you think?
>>
>> This RFC contains JSON float value precision change for PHP 5.6 so that =
PHP
>> would not loose floating number information, as well as more precise flo=
at
>> handling option for PHP 7.0.
>>
>> FYI, var_dump()'s float precision was changed to use serialize_precision=
 as bug
>> fix before.
>>
> Thanks for the ping. IMHO this is the stuff for 7.1. I actually saw the d=
iscussions previously, but was rather thinking you was targeting 7.1 as tha=
t was already the time of the feature freeze.

No problem. I'll update so that 0 mode is for 7.1.
JSON's is better to use larger precision. So this change is targeted
to 5.6 and 7.0.

Let me know if you have comments on this.

>
> Please keep in mind that we effectively have two RCs to do the remaining =
stabilizations. And we probably should as much as possible. Because this pa=
tch it's rather an enhancement to the current functionality which is not in=
deed broken - I wouldn't see it as critical for 7.0. It should be voted (an=
d discussed if necessary) for 7.1, so we don't loop away from our current s=
ituation.
>
> BTW I also had a comment there in the PR about https://github.com/php/php=
-src/pull/1455/files#diff-c84859666ff690a113d55ef1899d8bf4R149 - so if mode=
 0 ignores ndigits, why set it to 17 (or anything else). Seems like an unne=
cessary action, but snprintf is used quite frequently. But just as a notice=
 on the side.

"-1" which is invalid precision is used to indicate 0 mode.
0 mode is supposed to use max precision for double (it seems many
implementations
use 16, but PHP uses 17), when 0 mode is used, it uses 17 as precision alwa=
ys.

Regards,

--
Yasuo Ohgaki
yohgaki@ohgaki.net