rfc:deprecate_dynamic_properties
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rfc:deprecate_dynamic_properties [2021/10/12 10:16] – nikic | rfc:deprecate_dynamic_properties [2021/11/26 13:59] (current) – nikic | ||
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* Date: 2021-08-23 | * Date: 2021-08-23 | ||
* Author: Nikita Popov < | * Author: Nikita Popov < | ||
- | * Status: | + | * Status: |
* Target Version: PHP 8.2 | * Target Version: PHP 8.2 | ||
* Implementation: | * Implementation: | ||
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" | " | ||
+ | |||
+ | ==== Motivation ==== | ||
+ | |||
+ | The motivation for this change is twofold: To prevent mistakes (due to typos or renames) in the common case, and to make intentional uses explicit. The core problem is that reading from a non-existing property issues a diagnostic that makes the issue immediately apparent, while writing to a non-existing property is entirely silent. PHP gives no indication whatsoever that the programmer has made a mistake. | ||
+ | |||
+ | A common counter-argument is that even if PHP itself does not detect the mistake, static analysis still can. While this is true to a degree, there are a number of problems: | ||
+ | |||
+ | - Static analysis in IDEs (probably the most widespread type of static analysis used in PHP) has to be conservative about diagnostics relating to dynamic properties. For example, PhpStorm treats creation of dynamic properties as only a weak warning (non-intrusive grey underline), because it cannot distinguish whether this dynamic property assignment is indeed a bug, or an intentional use. Treating dynamic property creation as a more severe error would result in false positives in cases where dynamic properties are used intentionally. The ''# | ||
+ | - Static analysis can only analyze assignments with a known object type and property name. This does not include any kind of dynamic assignments, | ||
+ | - On a more philosophical note, I believe that a programming language should be usable without external tooling. While IDE use is widespread among PHP programmers, | ||
+ | |||
+ | Finally, if classes using dynamic properties are explicitly declared, then we no longer need to reserve space for them on each object. This would reduce the size of all objects (that don't opt-in to dynamic properties) by 8 bytes. However, this is a fairly long-term benefit that will require additional technical work to realize. | ||
===== Proposal ===== | ===== Proposal ===== | ||
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The difference between these approaches is in the end goal: ''# | The difference between these approaches is in the end goal: ''# | ||
- | While completely removing dynamic properties is an worthwhile end goal, we also need to acknowledge that dynamic properties have played an important historical role in PHP, and legacy codebases in particular may be making heavy use of them. While adding an attribute provides a straightforward upgrade path, extending '' | + | While completely removing dynamic properties is a worthwhile end goal, we also need to acknowledge that dynamic properties have played an important historical role in PHP, and legacy codebases in particular may be making heavy use of them. While adding an attribute provides a straightforward upgrade path, extending '' |
We may still wish to remove dynamic properties entirely at some later point. Having the ''# | We may still wish to remove dynamic properties entirely at some later point. Having the ''# | ||
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===== Vote ===== | ===== Vote ===== | ||
- | Yes/No. | + | Voting started 2021-11-12 and ended 2021-11-26. |
+ | |||
+ | <doodle title=" | ||
+ | | ||
+ | | ||
+ | </ |
rfc/deprecate_dynamic_properties.txt · Last modified: 2021/11/26 13:59 by nikic