PHP Dynamic Properties

Introduction for the mob programming session of December 17, 2021, with as the topic: scoping out the impact of the PHP 8.2 deprecation of dynamic properties.

Slides set forth the problem outline and review tasks.

Missed it ? The recording is (will be) available as video on demand at https://www.youtube.com/c/hellofromtonya/videos

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Links:
* PHP 8.2 RFC
* Results of initial test run of WP Core against PHP 8.2
* Exakat plugin scan results
* Spreadsheet to record findings

Transcript

1. PHP Dynamic Properties
   Scoping the impact of the PHP 8.2 deprecation
   Juliette Reinders Folmer Tweet about it: @jrf_nl
   

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2. Why are we talking
   about this ?
   ▪ Dynamic properties will be
   deprecated in PHP 8.2 (most likely)
   ▪ … and will become Error Exceptions
   (fatal errors) in PHP 9.0
   Full details:
   https://wiki.php.net/rfc/deprecate_
   dynamic_properties
   

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3. Why are we talking
   about this NOW ?
   ▪ Scope of problem is unknown
   ▪ Plugins often not actively maintained
   ▪ If not mitigated in time, could cause
   absolute havoc once PHP 9.0 comes
   round
   

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4. What Are Dynamic Properties ?
   class Foo {
   public $id;
   public function __construct( $id, $field_name ) {
   $this->id = $id;
   $this->field_name = $field_name;
   }
   }
   

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5. What Are Dynamic Properties ?
   class Foo_Parent {
   protected $field_name;
   }
   class Foo extends Foo_Parent {
   public $id;
   public function __construct( $id, $field_name ) {
   $this->id = $id;
   $this->field_name = $field_name;
   }
   }
   ✔
   

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6. What Are Dynamic Properties ?
   class Foo {
   private $fields = [];
   public function __construct($field_name ) {
   $this->field_name = $field_name;
   }
   public function __set( $name, $value ) {
   $this->fields[ $name ] = $value;
   }
   public function __get( $name ) { ... }
   public function __isset( $name ) { ... }
   public function __unset( $name ) { ... }
   }
   ✔
   

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7. What Are Dynamic Properties ?
   class Foo {
   public $id;
   public function __construct( $id, $field_name ) {
   $this->Id = $id;
   }
   }
   Typo
   

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8. Mitigation
   Options
   Typo Fix it
   Known dynamic
   properties
   Declare the properties on
   the (parent) class
   Unknown
   dynamic
   properties
   Add magic methods to the
   (parent) class
   Unknown use of
   dynamic
   properties
   Add
   #[AllowDynamicProperties]
   attribute to (parent) class
   

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9. Action Plan
   ❑Get insight into the scope of the problem
   ❑ Evaluate results of initial test run WP Core on PHP 8.2
   ❑ Validate Exakat analysis results for a sampling of plugins
   ❑Give feedback to PHP Core
   ❑Future livestream:
   Discuss proposal on how to handle this in WP
   Core and warn plugin authors and users in time
   

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10. Property
    Assignment
    Is there a property
    declared with a
    very similar
    name?
    Are the magic
    methods
    available?
    … in a potential
    parent class?
    Is the property
    declared in the
    class?
    … in a potential
    parent class?
    Not a Problematic
    Dynamic Property
    (false positive)
    Typo
    Problematic
    Dynamic
    Property
    Yes
    No
    No
    No
    No
    No Yes
    Yes
    

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11. Relevant links
    ▪ WP Core test run results
    https://github.com/jrfnl/wordpress-develop-official/actions
    ▪ Exakat plugin scan results
    https://is.gd/wpplugin_dynprop_review_input
    ▪ Spreadsheet to record findings
    https://is.gd/wpplugin_dynprop_review
    ▪ PHP 8.2 dynamic properties RFC
    https://wiki.php.net/rfc/deprecate_dynamic_properties
    

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12. Thanks!
    Any
    questions ?
    @jrf_nl @jrfnl
    

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