rfc:undefined_variable_error_promotion

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rfc:undefined_variable_error_promotion [2022/02/23 23:00] – marandallrfc:undefined_variable_error_promotion [2022/03/28 17:52] (current) – marandall
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   * Date: 2022-02-17   * Date: 2022-02-17
   * Author: Mark Randall marandall@php.net   * Author: Mark Randall marandall@php.net
-  * Status: Under Discussion+  * Status: Accepted
   * Target: PHP 9.0   * Target: PHP 9.0
   * First Published at: https://wiki.php.net/rfc/undefined_variable_error_promotion   * First Published at: https://wiki.php.net/rfc/undefined_variable_error_promotion
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 Undefined variables are those that have not yet been initialised with a value prior to being read. Accessing an undefined variable currently emits an E_WARNING "Warning: Undefined variable $varname" and treats the variable as if it were a null, but does not otherwise interrupt execution, allowing code execution to continue unabated, but likely in an unintended state. Undefined variables are those that have not yet been initialised with a value prior to being read. Accessing an undefined variable currently emits an E_WARNING "Warning: Undefined variable $varname" and treats the variable as if it were a null, but does not otherwise interrupt execution, allowing code execution to continue unabated, but likely in an unintended state.
  
-Although a custom error handler can already be used to raise an Error exception, this requires additional userland code to configure, when instead we should be aiming to provide a safer experience by default. The need to support calling a custom error handler does itself also introduce additional complexity into the engine, leading  to "increasingly complex games" to keep it working.+Although a custom error handler can already be used to raise an Error exception, this requires additional userland code to configure, when instead we should be aiming to provide a safer experience by default. The need to support calling a custom error handler does itself also introduce additional complexity into the engine, leading  to "increasingly complex games" to keep it working (see "Benefits"). 
 + 
 +**RFC History / Previous Votes**
  
 This change was last discussed during the Engine Warnings RFC (https://wiki.php.net/rfc/engine_warnings) where it received 56% in favour of making this behaviour an Error exception. It is likely that the only reason this vote failed to reach a supermajority at the time was because the condition was previously a notice, and some felt the jump from notice to error was too great for one version. Accessing undefined variables will have been a warning for 5+ years by the time this RFC would come into effect. This change was last discussed during the Engine Warnings RFC (https://wiki.php.net/rfc/engine_warnings) where it received 56% in favour of making this behaviour an Error exception. It is likely that the only reason this vote failed to reach a supermajority at the time was because the condition was previously a notice, and some felt the jump from notice to error was too great for one version. Accessing undefined variables will have been a warning for 5+ years by the time this RFC would come into effect.
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 Although the target version is mandated by our traditional breaking changes policy, it is also the intent of this RFC to give multiple years of notice that this change will be coming, affording the greatest opportunity for developers to modify their code in anticipation of this change. Although the target version is mandated by our traditional breaking changes policy, it is also the intent of this RFC to give multiple years of notice that this change will be coming, affording the greatest opportunity for developers to modify their code in anticipation of this change.
  
-A minor change may be included in the next minor version to change the existing warning message to indicate the warning will become an error in 9.0.+A minor change will be included in the next minor version to alter the existing warning message to indicate the warning will become an error in 9.0. 
 + 
 + 
 +===== Unaffected Functionality ===== 
 +If the code does not currently emit a "Warning: Undefined variable $varname" then it is out of scope for this RFC. This RFC does NOT apply to array indexes. 
 + 
 +===== Vote ===== 
 +Vote opened 2022-03-14, vote closes 2022-03-28 
 + 
 +<doodle title="Promote Undefined Variables to Throw an Error" auth="marandall" voteType="single" closed="true"> 
 +   * Yes 
 +   * No 
 +</doodle> 
 + 
 +Meta vote for reasoning of voting against:
  
-===== Proposed Voting Choices ===== +<doodle title="Main reason for voting against if you did?" auth="marandall" voteType="single" closed="true"> 
-Yes / No to promote to Error.+   * Using undefined variables is a legitimate coding style 
 +   * Backwards compatibility breaks 
 +   * Would be in favour, but not in 9.0 
 +   * Something else 
 +</doodle>
  
 ===== References ===== ===== References =====
rfc/undefined_variable_error_promotion.1645657243.txt.gz · Last modified: 2022/02/23 23:00 by marandall

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