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| rfc:php-namespace-in-core [2020/03/25 18:29] – created brzuchal | rfc:php-namespace-in-core [2020/04/15 20:37] – Use must instead of may, Changelog section, small nits girgias |
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| ====== PHP RFC: PHP Namespace in core ====== | ====== PHP RFC: PHP Namespace in core ====== |
| * Version: 0.9 | * Version: 1.1.0 |
| * Date: 2020-03-25 | * Date: 2020-03-25 |
| * Author: Michał Brzuchalski <brzuchal@php.net> | * Author: Michał Brzuchalski <brzuchal@php.net>, George Peter Banyard <girgias@php.net> |
| * Status: Draft | * Status: Under Discussion |
| * First Published at: http://wiki.php.net/rfc/php-namespace-in-core | * First Published at: http://wiki.php.net/rfc/php-namespace-in-core |
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| ===== Introduction ===== | ===== Introduction ===== |
| Introduce PHP namespace to core symbols which cannot be unbundled and are strictly language/parser/interpreter related as a way to fix some mistakes, clean up global namespace and to avoid collisions with user-defined symbols. | The PHP project has reserved the right to use the ''\PHP'' namespace but has never acted upon starting to use it. We therefore propose that core symbols which cannot be unbundled such as those related to the language/parser/interpreter must use ''\PHP'' namespace. |
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| Introduction of PHP namespace also as a way for gradual migration over renamed and marked as deprecated symbols reducing breaking changes. | This would provide a way to reduce the usage of the global namespace as "PHP"'s namespace and also provide a way to fix some fundamental misnaming. |
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| There is no concrete proposal on how to structure the namespaces and the only agreement is that core classes which are tightly coupled with the core can start using `PHP` namespace for type prefixes. | This is not a concrete proposal on how to structure the namespace or a proposal on realiasing classes to use the ''\PHP'' namespace. This is only an agreement that core classes or newly introduced symbols which are tightly coupled to the PHP engine must start using the ''\PHP'' namespace, e.g. for type prefixes. |
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| ===== Proposal ===== | ===== Features which could benefit from the PHP namespace ===== |
| This RFC proposes to introduce PHP namespace for internal symbols by utilizing the reserved PHP namespace as the root for the symbols that are tightly coupled with PHP interpreter. | |
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| ==== New symbols tightly coupled to the core ==== | * The recently accepted [[rfc:token_as_object|PHP RFC: Object-based token_get_all() alternative]] uses the <php>\PhpToken</php> class but under this proposal it could be <php>\PHP\PhpToken</php> |
| We can either have `PhpToken` and `PhpAttribute` classes of which the second one is a future RFC proposal. | * The currently under discussion [[rfc:attributes_v2|PHP RFC: Attributes v2]] could use the ''\PHP'' namespace for engine/internal related attributes. |
| But with the PHP namespace, those names can be clean like `PHP\Token` and `PHP\Attribute`. | |
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| That kind of symbols belongs only to the core. Therefore they will newer be unbundled and moved to PECL. | As these sort of symbols are tied to the engine there is no risk that they will get unbundled from PHP core and moved to PECL. We note this as we are aware that if a non core extension would use the ''\PHP'' namespace and gets unbundled and moved to PECL we would find ourselves in a situation where symbols under the ''\PHP'' namespace are not always available in PHP. |
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| In hypothetically new RFC for small refactor like was done for [[https://wiki.php.net/rfc/token_as_object|Object-based token_get_all() alternative]] | ==== A small toy-example ==== |
| for eg. `debug_backtrace()` which currently produces an array of arrays and introduction of a sort of `Frame` would be proposed for object-based alternative then `PHP` namespace is the natural owner of for eg. `PHP\Frame` without that we may cause some BC breaks in userland which is not likely to happen with `PHP` namespace prefix. | Currently <php>debug_backtrace()</php> produces and array of arrays. An object oriented API could introduce the <php>Frame</php> class to hold details about each frame in the backtrace. As this would be an internal API using the ''\PHP'' namespace this signals clear ownership and possibly limit the BC breaks for users which don't use the namespace feature of PHP. |
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| ==== Renaming to fix some mistakes ==== | ===== A chance to clean up poor design/naming decisions ===== |
| Currently we do have `ReflectionType` and `ReflectionNamedType` but their purpose isn't exactly to present a type. | Currently within the Reflection extension we have the following classes ''ReflectionType'' and ''ReflectionNamedType'' however their purpose isn't exactly to present a type. |
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| From type perspective, a class is a type therefore why `ReflectionClass` doesn't in its hierarchy extend `ReflectionType`? | From PHP's type system perspective, a class is a type. Therefore, ''ReflectionClass'' not extending from ''ReflectionType'' could be seen as questionable. Thus the ''ReflectionType'' class acts more as a type constraint and renaming it to ''ReflectionTypeConstraint'' may be a good way to clarify it's concern. |
| Current `ReflectionType` functions as a type constraint in general therefore renaming it to `ReflectionTypeConstraint` could be a good way to resolve those issues and concerns. | |
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| This RFC is not about renaming those classes but presents some mistakes taken in the past which cannot be changed between the PHP releases without a huge BC break. | This RFC could allow us to redesign, with the benefit of hindsight, some of the core APIs provided by PHP. |
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| What this RFC opens is a way to make some cleanups and in this specific example opens a way to alias `ReflectionType` as a `PHP\ReflectionTypeConstraint` (technically in the opposite direction) so then `PHP\ReflectionType` can be used as a top reflector for all kind of types which can be introduced in a future, like enums generics etc. | Continuing from the previous example we could alias ''ReflectionType'' to the more accurate ''PHP\ReflectionTypeConstraint'' class name, and possibly in the future introduce ''PHP\ReflectionType'' as the top reflector for all kinds of types which may be introduced in the future, e.g. Enums, Generics, etc. |
| Those kind of changes are not BC breaking changes allows to mark old classes as deprecated for a long period and use new class names in the meantime. | |
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| ===== Backward Incompatible Changes ===== | Another infamous example would be some of the data structures provides by the SPL extension. Indeed as <php> SplQueue extends SplDoublyLinkedList</php> this means that <php>SplQueue</php> inherits the <php>push()</php> and <php>pop()</php> methods from <php>SplDoublyLinkedList</php> meaning that if you decide to use these functions instead of the designated <php>enqueue()</php> and <php>dequeue()</php> methods you get something which behave like a stack instead of a queue. |
| No incompatible changes | |
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| ===== Proposed PHP Version(s) ===== | Although some of these concerns may be fixed with the introduction of the [[https://github.com/nikic/php-rfcs/blob/language-evolution/rfcs/0000-language-evolution.md|Language evolution]] RFC as this aspect of the proposal is a redesign once, live with it's imperfection forever. We still believe this may have some valid use cases which are not easily achieved with the fore-mentioned RFC. |
| Next PHP 8.x. | |
| | ===== Proposal ===== |
| | New features or symbols which are tightly coupled to the internals/engine of the PHP interpreter must use the ''\PHP'' namespace starting from PHP 8. |
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| ===== RFC Impact ===== | ===== Backward Incompatible Changes ===== |
| ==== To SAPIs ==== | No backwards incompatible changes as only new classes/symbols would be introduces under the ''\PHP'' namespace. |
| None. | |
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| ==== To Existing Extensions ==== | ===== Proposed PHP Version ===== |
| None. | PHP 8.0. |
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| ==== To Opcache ==== | |
| None. | |
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| ==== New Constants ==== | |
| None. | |
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| ===== Proposed Voting Choices ===== | ===== Proposed Voting Choices ===== |
| As this is a language change, a 2/3 majority is required. | The vote is a straight Yes/No vote requiring a 2/3 majority to accept the RFC. |
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| The vote is a straight Yes/No vote for accepting the RFC. | |
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| ===== Patches and Tests ===== | ===== Patches and Tests ===== |
| This RFC doesn't provide any changes. | This RFC doesn't provide any changes. |
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| | ===== Changelog ===== |
| | 1.0.0: Initial version \\ |
| | 1.1.0: New features must use the PHP engine, before this was merely a suggestion \\ |
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