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Date: Fri, 10 Nov 2023 08:00:51 +0900
Cc: PHP internals <internals@lists.php.net>
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Message-ID: <A5205FBA-D4ED-4331-9963-B9088BBA2A24@sakiot.com>
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To: Jordan LeDoux <jordan.ledoux@gmail.com>
Subject: Re: [PHP-DEV] [RFC] [Discussion] Change the edge case of round()
From: saki@sakiot.com (Saki Takamachi)

Hi Jordan,

> 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.
>=20
> 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.

Yes, that's a valid concern. Therefore, I am also proposing to add a =
function similar to round to BCMath. In a sense, we can think that we =
are looking for the same functionality in round() that we should be =
looking for in BCMath.


> 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.

In terms of "not lying about the results", this RFC makes us more =
precise about dealing with FP. However, in terms of benefits for users, =
there may not be any significant benefits.

Regards.

Saki