Table of Contents

PHP RFC: Null Coalescing Assignment Operator

Introduction

Combined assignment operators have been around since 1970's, appearing first in the C Programming Language. For example, $x = $x + 3 can be shortened to $x += 3. With PHP being a web focused language, the ?? operator is often used to check something's existence like $username = $_GET['user'] ?? 'nobody'; However, because variable names are often much longer than $username, the use of ?? for self assignment creates repeated code, like $this->request->data['comments']['user_id'] = $this->request->data['comments']['user_id'] ?? ‘value’;. It is also intuitive to use combined assignment operator null coalesce checking for self assignment.

Proposal

Despite ?? coalescing operator being a comparison operator, coalesce equal or ??=operator is an assignment operator. If the left parameter is null, assigns the value of the right paramater to the left one. If the value is not null, nothing is made.

// The folloving lines are doing the same
$this->request->data['comments']['user_id'] = $this->request->data['comments']['user_id'] ?? 'value';
// Instead of repeating variables with long names, the equal coalesce operator is used
$this->request->data['comments']['user_id'] ??= 'value';

The value of right-hand parameter is copied if the left-hand parameter is null.

Proposed PHP Version(s)

This proposed for the next PHP 7.x.

Patches and Tests

A pull request with a working implementation, targeting master, is here: https://github.com/php/php-src/pull/1795

Vote

As this is a language change, a 2/3 majority is required. A straight Yes/No vote is being held.

Voting started at 2016/03/24 16:08 and will be closed at 2016/04/02.

Approve Equal Null Coalesce Operator RFC and merge patch into master?
Real name Yes No
aharvey  
ajf  
brianlmoon  
colinodell  
daverandom  
davey  
dmitry  
dragoonis  
francois  
frozenfire  
galvao  
guilhermeblanco  
jwage  
klaussilveira  
krakjoe  
laruence  
lcobucci  
leigh  
levim  
lstrojny  
malukenho  
marcio  
mariano  
mbeccati  
mcmic  
mrook  
ocramius  
patrickallaert  
pauloelr  
pierrick  
pollita  
ralphschindler  
stas  
svpernova09  
toby  
tpunt  
trowski  
weierophinney  
yohgaki  
zeev  
zimt  
Final result: 37 4
This poll has been closed.

References

Links to external references, discussions or RFCs

http://programmers.stackexchange.com/questions/134118/why-are-shortcuts-like-x-y-considered-good-practice

Rejected Features

Keep this updated with features that were discussed on the mail lists.