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To: "'Nikita Popov'" <nikita.ppv@gmail.com>
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References: <046401d6e999$f4de5d50$de9b17f0$@adsar.co.uk> <CAF+90c_D5c_5pyHx6Wxus2w6qcxnQfoFMreaRWukDkx+K=Wntg@mail.gmail.com>
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Date: Mon, 18 Jan 2021 11:11:02 -0000
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Subject: RE: [PHP-DEV] Addition of substring and subistring functions.
From: adam@adsar.co.uk ("Adam Cable")



From: Nikita Popov <nikita.ppv@gmail.com>=20
Sent: 18 January 2021 10:32
To: Adam Cable <adam@adsar.co.uk>
Cc: PHP internals <internals@lists.php.net>
Subject: Re: [PHP-DEV] Addition of substring and subistring functions.

On Wed, Jan 13, 2021 at 11:51 AM Adam Cable <mailto:adam@adsar.co.uk> =
wrote:
Hi internals.

I've been coding in PHP for 15 years now, and spend most days using it =
to
transform content into meaningful data.

Most of this is pulling out prices and attributes of certain products =
from
HTML, for example, grabbing the price from content such as "Total price
including delivery: &pound;15.00".

To grab the "15.00" from the string can take quite a few lines of PHP =
and
can be pretty cumbersome.

I've built some helper functions - substring, and it's case-insensitive
variant subistring to help.
Functions take in the string plus a to and from string, and return a =
trim'd
string found between the two.

So substring("Total price including delivery: &pound;15.00", "&pound;", =
"")
would return "15.00".
>From and to strings are optional and therefore return from the =
beginning or
to the end.

In the past I hadn't thought about adding this to PHP core, but with the
introduction of str_starts/ends_with functions in PHP 8.0 I thought it =
may
be useful to include the sub(i)string building blocks too.

Implementation and tests can be found @
https://github.com/php/php-src/pull/6602

I'm sure the C implementation can be made a lot better, but it seems to =
work
OK at present.

This is my first e-mail to internals, so please excuse my naivety with
things, but hope this is useful.

Thanks,
Adam

Hi Adam,

A few thoughts:
1. The name of the function is not clear. It's not obvious what the =
difference between substr() and substring() is. To make it worse, =
JavaScript has both substr() and substring(), but the meaning of =
substring() there is a different one from what you propose. I think a =
better name would be something like str_between().
2. Why does this perform an implicit trim() call? I understand that this =
may be useful in some cases, but it will also limit applicability of the =
function. It's easy to write trim(substring(...)), but if the trim() is =
part of the call, there's no way to avoid it.
3. More generally, I feel that this API is a bit too specific for =
inclusion in the standard library. It can certainly be useful, but I =
don't think it's anywhere near as ubiquitous as operations like =
str_ends_with(). For complex string matching tasks, I would probably =
pick preg_match() over a combination of str* functions anyway.

Regards,
Nikita


Hi Nikita,

Thanks for the reply, appreciated.

Answers below:
1 - str_between() makes much more sense to align with similar PHP =
function names
2 - We have never had a time when excess whitespace was wanted - but it =
doesn't need to trim
3 - That's fine, just thought I'd propose it as I use this nearly every =
day, and helps to keep things simple when regex might be a bit overkill

Happy to leave this for now - but again, appreciate the reply.

Best,
Adam