Re: [RFC] Combined Comparison Operator

From: Date: Thu, 13 Feb 2014 04:39:39 +0000
Subject: Re: [RFC] Combined Comparison Operator
References: 1 2  Groups: php.internals 
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On 2/12/14, 11:25 PM, Yasuo Ohgaki wrote:

Hi Davey,

On Thu, Feb 13, 2014 at 12:58 PM, Davey Shafik <[email protected]> wrote:


I've written up an RFC/Patch to gauge interest and get feedback on the
addition of a combined comparison (aka: spaceship) operator.

You can see the RFC at: https://wiki.php.net/rfc/
combined-comparison-operator

This adds a new operator "(expr) <=> (expr)" that returns 0 if both
operands are equal, 1 if the left is greater, and -1 if the right is
greater.

It works with all types (just as well as <, <=, >=, > work) and is great
for usort() callbacks for example.

Code available here (against 5.6): https://github.com/dshafik/
php-src/compare/add-spaceship-operator

I'd love to get this into 5.6, not sure if we hit feature freeze yet.
Also, not sure if it needs 2/3 majority, but assumed so as pow did?

Thoughts?

If there is interest, I'll start adding tests. They should be fairly
trivial.



Interesting shortcut operator.
I feel closure function is for the task.
I would vote 0, but close to -1 since it's only useful for sorting.
Is there any other use cases?

Regards,

--
Yasuo Ohgaki
[email protected]



Yasuo,

Sorting is definitely it's most compelling use. It cuts down on potentially quite a bit of code:

function ($left, $right) {

    if ($left[1] == $right[1]) {
         return 0;
    }



    if ($left[1] > $right[1]) {
         return 1;
    }



    if ($left[1] < $right[1]) {
        return -1;
    }

}

or (as per the RFC):

function ($left, $right) {

    return $left[1] <=> $right[1];

}

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