Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:105455
To: Benjamin Morel <benjamin.morel@gmail.com>,
 Vladyslav Startsev <vladyslavstartsev@gmail.com>
Cc: "Legale.legale" <legale.legale@gmail.com>, Ben Ramsey
 <ben@benramsey.com>, PHP Internals <internals@lists.php.net>
References: <5c633ed8.1c69fb81.143ab.ad85@mx.google.com>
 <CAEQoxLLncOfiSvB23=yTOF8D5D0Ba=YC96eqP0XWJXAz5xw6Yg@mail.gmail.com>
 <CAG9XoMT1WFLKMjC1o6mPkvv4zPu1D+6NpgP9VYx4ppYocjRmjw@mail.gmail.com>
 <CAEQoxLL8a6DhyDmEdBbNUfGCqy04UeLAK6HQO=zYrVbGG2w40w@mail.gmail.com>
 <CAG9XoMQkZYP9wNNu0tQYTcuWJPx=4u7NfSdPCQDjo7O3o02OxA@mail.gmail.com>
Message-ID: <6a97cecf-7a5d-6476-7773-fdd41aa45646@gmx.de>
Date: Fri, 26 Apr 2019 11:33:04 +0200
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101
 Thunderbird/60.6.1
MIME-Version: 1.0
In-Reply-To: <CAG9XoMQkZYP9wNNu0tQYTcuWJPx=4u7NfSdPCQDjo7O3o02OxA@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: de-DE
Content-Transfer-Encoding: quoted-printable
Subject: Re: [PHP-DEV] Make bcmath functions more strict
From: cmbecker69@gmx.de ("Christoph M. Becker")

On 26.04.2019 at 09:45, Benjamin Morel wrote:

>> I don't really understand it, I must be strict, converting to zero
>> will lead to wrong calculations.
>
> That's what I said :) Fully agree here, any non-numeric string should th=
row
> an exception.
>
> In summary, I would check that the string matches `
> /^[\+\-]?[0-9]+(\.[0-9]+)?$/`or else throw an exception.

Throwing an exception would be rather uncommon for functions, and would
definitely have to wait for PHP 8 for BC reasons.  Another option might
be to introduce an object-oriented layer on top of libbcmath.  A basic
problem of the BC extension is that all functions accept strings,
convert these to bc_nums[1], do the actual calculation, convert the
bc_nums back to strings[2], and return these.  This looks like quite
some overhead, especially for more complex calculations where the
intermediary results are not even needed as strings.  If there is an OOP
API, the conversion from string would only be needed in the constructor,
and conversion to string only in the __toString() method.  All
intermediary calculations wouldn't need the from/to string conversions.
And of course, users could switch to the OOP API if they desire, but
could stick with the procedural API otherwise.  An additional benefit
might be that we sometime could switch away from the decimal storage[3]
which appears to be mostly useful for the string conversions, but is
otherwise wasteful (1 byte per decimal digit).

[1]
<https://github.com/php/php-src/blob/php-7.3.4/ext/bcmath/libbcmath/src/st=
r2num.c#L44>
[2]
<https://github.com/php/php-src/blob/php-7.3.4/ext/bcmath/libbcmath/src/nu=
m2str.c>
[3]
<https://github.com/php/php-src/blob/php-7.3.4/ext/bcmath/libbcmath/src/bc=
math.h#L61-L64>

=2D-
Christoph M. Becker