Syntactic support for PHP enums#23
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Enums are by design a closed list, which inheritance would violate. Interfaces are allowed, but not parent classes.
thekid
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Mar 8, 2021
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| $decl= new EnumDeclaration([], $name, $implements, [], [], $comment, $token->line); | ||
| $parse->expecting('{', 'enum'); | ||
| $decl->body= $this->typeBody($parse, $decl->name); |
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This is not completely correct, as typeBody() allows properties, which PHP enums do not. The RFC states this:
Specifically, the following features of objects are not allowed on enumerations: [...] Enum/Case properties - Properties are a form of state, and enum cases are stateless singletons. Metadata about an enum or case can always be exposed via methods.
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We'll leave this as-is, the compiler may chose to raise errors about this; or we simply leave it to the PHP runtime.
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Mar 10, 2021
thekid
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Mar 12, 2021
https://wiki.php.net/rfc/enumerations#grouped_syntax states that this "may cause syntactic issues with the planned addition of tagged unions", which are defined in https://wiki.php.net/rfc/tagged_unions and may be one of the following: case None { } case Some(private mixed $value) { ... } ...in addition to the existing declarations: case ASC; case DESC = "desc"; In none of these case would a comma be ambiguous, therefore I think we might as well have it, thus allowing more concise syntax for enum declarations
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See xp-framework/compiler#100
Unit enums
Backed enums
Grouped syntax
https://wiki.php.net/rfc/enumerations#grouped_syntax states that this "may cause syntactic issues with the planned addition of tagged unions", which are defined in https://wiki.php.net/rfc/tagged_unions and may be one of the following:
case None { }case Some(private mixed $value) { ... }...in addition to the existing declarations:
case ASCcase DESC = 'desc'In none of these cases would a comma be ambiguous, therefore I think we might as well have it, thus allowing more concise syntax for enum declarations