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Date: Thu, 9 Nov 2023 12:53:41 -0800
Message-ID: <CAMrTa2GRW627AYzCnTDgy7zXpFyZ2of_1GR0cr3YceDE0XjNtQ@mail.gmail.com>
To: Saki Takamachi <saki@sakiot.com>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] [Discussion] Change the edge case of round()
From: jordan.ledoux@gmail.com (Jordan LeDoux)

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On Mon, Oct 23, 2023 at 4:14=E2=80=AFAM Saki Takamachi <saki@sakiot.com> wr=
ote:

> Hi, internals
>
> I would like to start the discussion for my RFC "Change the edge case of
> round()=E2=80=9D.
> https://wiki.php.net/rfc/change_the_edge_case_of_round <
> https://wiki.php.net/rfc/adding_bcround_bcfloor_bcceil_to_bcmath>
>
> Regards.
>
> Saki
> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: https://www.php.net/unsub.php
>
>
I think this makes much more sense if PHP programmers had internal access
to the float type in PHP, but that's not the case. You cannot choose
between float representations, you cannot easily examine the mantissa bits
directly. In the absence of stuff like that, I think the argument to treat
PHP floats as if they were decimals for the purposes of rounding is much
stronger.

That said, this sort of 'intelligent' rounding certainly introduces a large
number of edge cases. Additionally, if PHP programmers expect decimal
rounding to "just work", then it feels like anywhere that it doesn't work
the way they think it should is a bug, which isn't necessarily true.

I'm unsure whether or not this change actually improves anything. Is it
more correct from a technical perspective? Absolutely. Does it provide a
benefit for PHP programmers? That I am much less certain about.

Jordan

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