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Date: Wed, 23 Jun 2021 02:25:26 +0200
To: internals@lists.php.net
Subject: Proposal: clamp
From: hallbergkim@gmail.com (Kim Hallberg)

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Greetings internals,

I present to you a proposal for a new basic math function: clamp.

The main goal of this function is to contain a number inside a given =
bound.
And return the number if it is inside of that bound, and if not, and the=20=

number is outside of the given bound, the nearest bound is returned.

Now, does this need an RFC? The behaviour can be implemented in userland=20=

in a number of ways, one of which is to compare the values in a if =
statement.
Another is to use the min and max math functions.

max($min, min($max, $num));

I don=E2=80=99t have any schpeel as to why this should be in core, only =
that I thought it already was.
Considering it is part of other languages standard math library, and it =
is a useful function.

Can see this being useful in image manipulation, server-side rendering =
and math just to name few.

The proposed signature follows the convention of other math related =
functions.

function clamp(int|float $num, int|float $min, int|float $max): =
int|float {}

This function is very easy to implement, has no side effects or backward
compatibility issues, unless a userland implementation already has the =
function declared,
in which case PHP will throw a fatal error since the function cannot be =
redeclared.

I've implemented this feature a few months ago already.
- Link: https://github.com/thinkverse/php-src/pull/1 =
<https://github.com/thinkverse/php-src/pull/1>

What are your opinions on this function?

Regards,
Kim Hallberg.

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