rfc:allow_null

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision		Previous revision
Next revisionBoth sides next revision
rfc:allow_null [2021/12/30 02:59] – Draft updates craigfrancisrfc:allow_null [2022/02/08 15:31] – craigfrancis
Line 1: Line 1:
 ====== PHP RFC: Allow NULL ====== ====== PHP RFC: Allow NULL ======
  
-  * Version: 1.0+  * Version: 1.2
   * Voting Start: ?   * Voting Start: ?
   * Voting End: ?   * Voting End: ?
   * RFC Started: 2021-12-23   * RFC Started: 2021-12-23
-  * RFC Updated: 2021-12-23+  * RFC Updated: 2021-12-31
   * Author: Craig Francis, craig#at#craigfrancis.co.uk   * Author: Craig Francis, craig#at#craigfrancis.co.uk
   * Status: Draft   * Status: Draft
Line 14: Line 14:
 ===== Introduction ===== ===== Introduction =====
  
-PHP 8.1 introduced "Deprecate passing null to non-nullable arguments of internal functions" ([[https://externals.io/message/112327|short discussion]]), which is making it difficult for developers to upgrade.+PHP 8.1 introduced "Deprecate passing null to non-nullable arguments of internal functions" ([[https://externals.io/message/112327|short discussion]]), which is making it difficult (time consuming) for developers to upgrade.
  
-Often //NULL// is used for undefined //GET/////POST/////COOKIE// variables:+In PHP //NULL// is often used to represent something; e.g. when a //GET/////POST/////COOKIE// variable is undefined:
  
 <code php> <code php>
Line 27: Line 27:
 </code> </code>
  
-And //NULL// can be returned from many functions, e.g.+And //NULL// can be returned from functions, e.g.
  
   * //array_pop()//   * //array_pop()//
Line 35: Line 35:
   * //json_decode()//   * //json_decode()//
  
-Which makes it common for developers to pass potential //NULL// values to these internal functions, e.g.+This makes it common for //NULL// to be passed to many internal functions, e.g.
  
 <code php> <code php>
Line 50: Line 50:
 </code> </code>
  
-Currently this affects those using PHP 8.1 with //E_DEPRECATED//, but it implies everyone will need to modify their code in the future.+Where //NULL// has the advantage of falling back to being treated like an empty string.
  
-It also applies even if they are not using //strict_types=1//.+Developers also use //NULL// to skip certain parameters, e.g. //$additional_headers// in //mail()//.
  
-And while the individual modifications are easy, there are many of them, they are difficult to find, and often pointless (e.g. //urlencode(strval($name))//).+Currently the deprecation notices only affect those using PHP 8.1 with //E_DEPRECATED//, but it implies everyone will need to modify their code to avoid **Fatal Errors** in PHP 9.0.
  
-Without the changes listed below, developers will need to either use these deprecation warnings, or use strict Static Analysis (one that can determine when a variable can be //NULL//; e.g. Psalm at [[https://psalm.dev/docs/running_psalm/error_levels/|level 3]], with no baseline).+Developers using //strict_types=1// may find some value in this, but it's excessive for everyone else. 
 + 
 +And while individual changes are easy, there are many of them, are difficult to find, and often pointless, e.g. 
 + 
 +  * urlencode(strval($name)); 
 +  * urlencode((string) $name); 
 +  * urlencode($name ?? ''); 
 + 
 +To find these issues, developers need to either - use these deprecation notices, or use very strict Static Analysis (one that can determine when a variable can be //NULL//; e.g. Psalm at [[https://psalm.dev/docs/running_psalm/error_levels/|level 3]], with no baseline).
  
 ===== Proposal ===== ===== Proposal =====
  
-Update **some** internal function parameters to accept NULL, to reduce the burden for developers upgrading.+Update **some** internal function parameters to accept (or be tolerant to) //NULL//.
  
-While this is in Draft, the [[https://github.com/craigfrancis/php-allow-null-rfc/blob/main/functions-change.md|list of functions is hosted on GitHub]] (pull requests welcome):+This needs to be done before the eventual end of the deprecation period, and //TypeError// exceptions are thrown - which would create an unnecessary burden for developers to upgrade.
  
-===== Decision Process =====+While this is in Draft, the [[https://github.com/craigfrancis/php-allow-null-rfc/blob/main/functions-change.md|list of functions are hosted on GitHub]].
  
-Does the parameter work with //NULL//, in the same way that it would if an empty string is provided? e.g.+Only the parameters in **bold** would be changed.
  
-  - //preg_match()// should continue to deprecate //NULL// for //$pattern//, whereas //$subject// should accept //NULL//. +[[https://github.com/craigfrancis/php-allow-null-rfc/issues|Suggestions]] and [[https://github.com/craigfrancis/php-allow-null-rfc/pulls|pull requests]] welcome.
-  - //hash_file()// should continue to deprecate //NULL// for the //$filename//. +
-  - //hash()// should accept //NULL// for //$data//. +
-  - //substr_count()// requires a non-empty string //$needle// (continue to deprecate //NULL//). +
-  - //mb_convert_encoding()// requires a valid encoding for //$to_encoding// (continue to deprecate //NULL//).+
  
-You could argue some function parameters should not accept an empty string either (e.g. //strpos()// accepting an empty string for //$needle//), but that would require different RFCs, where backwards compatibility would need to be discussed.+There is also a [[https://github.com/craigfrancis/php-allow-null-rfc/blob/main/functions-maybe.md|Maybe List]], where the more questionable arguments end with a "!". For example, //strrpos()// accepting an empty string for //$needle// is wired in itself, and //sodium_crypto_box_open()// should never receive a blank //$ciphertext//. And there is an [[https://github.com/craigfrancis/php-allow-null-rfc/blob/main/functions-other.md|Other List]], which can be ignored. 
 + 
 +===== Decision Process ===== 
 + 
 +Does //NULL// for this parameter justify a Fatal Error? e.g. 
 + 
 +  - //preg_match()// should **deprecate** //NULL// for //$pattern// ("empty regular expression" warning). 
 +  - //preg_match()// should **accept** //NULL// for //$subject// (e.g. checking user input). 
 +  - //hash_file()// should **deprecate** //NULL// for the //$filename//. 
 +  - //hash()// should **accept** //NULL// for //$data//. 
 +  - //substr_count()// should **deprecate** //NULL// for //$needle// ("$needle cannot be empty" error). 
 +  - //mb_convert_encoding()// should **deprecate** //NULL// for //$to_encoding// (requires a valid encoding).
  
 ===== Backward Incompatible Changes ===== ===== Backward Incompatible Changes =====
Line 100: Line 115:
 ===== Open Issues ===== ===== Open Issues =====
  
-TODO+Is the [[https://github.com/craigfrancis/php-allow-null-rfc/blob/main/functions-change.md|list of functions]] complete?
  
 ===== Future Scope ===== ===== Future Scope =====
  
-None+Some function parameters could be updated to complain when an Empty String or //NULL// is provided; e.g. //$method// in //method_exists()//, or //$characters// in //trim()//.
  
 ===== Voting ===== ===== Voting =====
Line 112: Line 127:
 TODO TODO
  
-===== Patches and Tests =====+===== Tests =====
  
-TODO+To get and **Test** the list of functions, I wrote a script to //get_defined_functions()//, then used //ReflectionFunction()// to identify parameters that accepted the 'string' type, and not //->allowsNull()//. This resulted in the [[https://github.com/craigfrancis/php-allow-null-rfc/blob/main/functions-change.md|list of functions to change]], where I manually removed the [[https://github.com/craigfrancis/php-allow-null-rfc/blob/main/functions-other.md|functions that shouldn't be changed]], and updated the script to test every argument (to see that it complained with //NULL//, and the output remained the same) - [[https://github.com/craigfrancis/php-allow-null-rfc/blob/main/functions.php|Source]].
  
 ===== Implementation ===== ===== Implementation =====
  
-TODO+https://github.com/craigfrancis/php-src/compare/master...allow-null 
 + 
 +This patch defines //Z_PARAM_STR_ALLOW_NULL//. 
 + 
 +It works a bit like //Z_PARAM_STR_OR_NULL//, but it will return an empty string instead of //NULL//. 
 + 
 +It's a fairly easy drop in replacement for //Z_PARAM_STR//, e.g. [[https://github.com/php/php-src/blob/7b90ebeb3f954123915f6d62fb7b2cd3fdf3c6ec/ext/standard/html.c#L1324|htmlspecialchars()]].
  
 ===== Rejected Features ===== ===== Rejected Features =====
rfc/allow_null.txt · Last modified: 2022/04/05 17:49 by craigfrancis

Page Tools