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Date: Mon, 20 Dec 2021 23:02:56 +0000
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To: Stanislav Malyshev <smalyshev@gmail.com>
Cc: internals@lists.php.net
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [PHP-DEV] [RFC] User Defined Operator Overloads (v0.6)
From: Danack@basereality.com (Dan Ackroyd)

On Fri, 17 Dec 2021 at 18:36, Stanislav Malyshev <smalyshev@gmail.com> wrote:
>
> When reading
> this code: $foo * $bar - how do I know which of the ways you took and
> where should I look for the code that is responsible for it? When I see
> $foo->times($bar) it's clear who's in charge and where I find the code.
> Terse code is nice but not at the expense of making it write-only.

Well, there's only two places  to look with operator overloads, but
yes you're right, using operator overloads for single operation is not
a good example of how they make code easier to read. The more
complicated example from the introduction to the RFC
https://wiki.php.net/rfc/user_defined_operator_overloads#introduction
shows how they make complex maths easier to read.

The exact position of where that trade-off is 'worth it' is going to
be different for different people. But one of the areas where PHP is
'losing ground' to Python is how Python is better at processing data
with maths, and part of that is how even trivial things, such as
complex numbers, are quite difficult to implement and/or use in
userland PHP.

Stanislav Malyshev wrote:
> And again, what's the intuitive
> difference between operators +=+@-+ and ++--=!* ?

That's not part of the RFC.

There's enough trade-offs to discuss already; people don't need to
imagine more that aren't part of what is being proposed.

> I have encountered
> toolkits where the authors think it's cute to define "+" to mean
> something that has nothing to do with mathematical addition

Rather than leaving everyone to make the same mistakes again, this RFC
might be improved by having a list of stuff that it really shouldn't
be used for. At least then anyone who violates those guidelines does
so at their own risk. Having guidelines would also help junior devs
point out to more senior devs that "you're trying to be clever and the
whole team is going to regret this".

I started a 'Guidelines for operator overloads' here
(https://github.com/Danack/GuidelinesForOperatorOverloads/blob/main/guidelines.md)
- if anyone has horrorible examples they'd like to add, PR's are
welcome.

cheers
Dan
Ack