rfc:null_coalesce_equal_operator

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rfc:null_coalesce_equal_operator [2016/03/09 17:03] – created midorikocakrfc:null_coalesce_equal_operator [2019/01/22 10:36] (current) – Implemented nikic
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-====== PHP RFC: Null Coalesce Equal Operator ====== +====== PHP RFC: Null Coalescing Assignment Operator ====== 
-  * Version: 0.9 +  * Version: 0.1.0 
-  * Date: 2016-03-09 (use today's date here)+  * Date: 2016-03-09
   * Author: Midori Kocak, mtkocak@gmail.com   * Author: Midori Kocak, mtkocak@gmail.com
-  * Status: Draft (or Under Discussion or Accepted or Declined)+  * Status: Implemented (in PHP 7.4)
   * First Published at: http://wiki.php.net/rfc/null_coalesce_equal_operator   * First Published at: http://wiki.php.net/rfc/null_coalesce_equal_operator
 +
  
 ===== Introduction ===== ===== Introduction =====
  
-This is a suggested template for PHP Request for Comments (RFCs). Change this template to suit your RFC.  Not all RFCs need to be tightly specified.  Not all RFCs need all the sections below. +Combined assignment operators have been around since 1970's, appearing first in the C Programming Language. For example, ''<nowiki>$x = $x + 3</nowiki>''  can be shortened to ''<nowiki>$x += 3</nowiki>''. With PHP being a web focused language, the ''??'' operator is often used to check something's existence like ''<nowiki>$username = $_GET['user'] ?? 'nobody';</nowiki>''  However, because variable names are often much longer than $username, the use of ?? for self assignment creates repeated code, like ''<nowiki>$this->request->data['comments']['user_id'] = $this->request->data['comments']['user_id'] ?? ‘value’;</nowiki>''. It is also intuitive to use combined assignment operator null coalesce checking for self assignment. 
-Read https://wiki.php.net/rfc/howto carefully! +
- +
- +
-Quoting [[http://news.php.net/php.internals/71525|Rasmus]]: +
- +
-> PHP is and should remain: +
-> 1) a pragmatic web-focused language +
-> 2) a loosely typed language +
-> 3) a language which caters to the skill-levels and platforms of a wide range of users +
- +
-Your RFC should move PHP forward following his vision. As [[http://news.php.net/php.internals/66065|said by Zeev Suraski]] "Consider only features which have significant traction to a +
-large chunk of our userbase, and not something that could be useful in some +
-extremely specialized edge cases [...] Make sure you think about the full context, the huge audience out there, the consequences of  making the learning curve steeper with +
-every new feature, and the scope of the goodness that those new features bring." +
- +
-===== Introduction ===== +
-The elevator pitch for the RFC. The first paragraph in this section will be slightly larger to give it emphasis; please write a good introduction.+
  
 ===== Proposal ===== ===== Proposal =====
-All the features and examples of the proposal. 
  
-To [[http://news.php.net/php.internals/66051|paraphrase Zeev Suraski]], explain hows the proposal brings substantial value to be considered +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.
-for inclusion in one of the world's most popular programming languages.+
  
-Remember that the RFC contents should be easily reusable in the PHP Documentation.+<code php> 
 +// 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'; 
 +</code>
  
-===== Backward Incompatible Changes ===== +The value of right-hand parameter is copied if the left-hand parameter is null. 
-What breaks, and what is the justification for it?+
  
 ===== Proposed PHP Version(s) ===== ===== Proposed PHP Version(s) =====
-List the proposed PHP versions that the feature will be included in.  Use relative versions such as "next PHP 7.x" or "next PHP 7.x.y". 
  
-===== RFC Impact ===== +This proposed for the next PHP 7.x.
-==== To SAPIs ==== +
-Describe the impact to CLI, Development web server, embedded PHP etc.+
  
-==== To Existing Extensions ==== +===== Patches and Tests =====
-Will existing extensions be affected?+
  
-==== To Opcache ==== +A pull request with a working implementation, targeting master, is here: https://github.com/php/php-src/pull/1795
-It is necessary to develop RFC's with opcache in mind, since opcache is a core extension distributed with PHP.+
  
-Please explain how you have verified your RFC's compatibility with opcache.+===== Vote =====
  
-==== New Constants ==== +As this is a language change, a 2/3 majority is required. A straight Yes/No vote is being held.
-Describe any new constants so they can be accurately and comprehensively explained in the PHP documentation.+
  
-==== php.ini Defaults ==== +Voting started at 2016/03/24 16:08 and will be closed at 2016/04/02.
-If there are any php.ini settings then list: +
-  * hardcoded default values +
-  * php.ini-development values +
-  * php.ini-production values+
  
-===== Open Issues ===== +<doodle title="Approve Equal Null Coalesce Operator RFC and merge patch into master?" auth="midorkocak" voteType="single" closed="true"> 
-Make sure there are no open issues when the vote starts! +   * Yes 
- +   * No 
-===== Unaffected PHP Functionality ===== +</doodle>
-List existing areas/features of PHP that will not be changed by the RFC. +
- +
-This helps avoid any ambiguity, shows that you have thought deeply about the RFC's impact, and helps reduces mail list noise. +
- +
-===== Future Scope ===== +
-This sections details areas where the feature might be improved in future, but that are not currently proposed in this RFC. +
- +
-===== Proposed Voting Choices ===== +
-Include these so readers know where you are heading and can discuss the proposed voting options. +
- +
-State whether this project requires a 2/3 or 50%+1 majority (see [[voting]]) +
- +
-===== Patches and Tests ===== +
-Links to any external patches and tests go here. +
- +
-If there is no patch, make it clear who will create a patch, or whether a volunteer to help with implementation is needed. +
- +
-Make it clear if the patch is intended to be the final patch, or is just a prototype. +
- +
-===== Implementation ===== +
-After the project is implemented, this section should contain  +
-  - the version(s) it was merged to +
-  - a link to the git commit(s) +
-  - a link to the PHP manual entry for the feature+
  
 ===== References ===== ===== References =====
 Links to external references, discussions or RFCs Links to external references, discussions or RFCs
 +
 +http://programmers.stackexchange.com/questions/134118/why-are-shortcuts-like-x-y-considered-good-practice
  
 ===== Rejected Features ===== ===== Rejected Features =====
 Keep this updated with features that were discussed on the mail lists. Keep this updated with features that were discussed on the mail lists.
rfc/null_coalesce_equal_operator.1457542991.txt.gz · Last modified: 2017/09/22 13:28 (external edit)

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