mirror of
https://github.com/mruby/mruby
synced 2026-06-08 16:11:16 +00:00
Yukihiro "Matz" Matsumoto
82 lines
2.9 KiB
Markdown
82 lines
2.9 KiB
Markdown
# mruby-class-ext
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This mrbgem extends the `Module` and `Class` classes in mruby, providing additional methods for reflection and class manipulation.
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## Module Methods
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### `mod < other`
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Returns `true` if `mod` is a subclass of `other`. Returns `nil` if there's no relationship between the two. (Think of the relationship in terms of the class definition: "class A < B" implies "A < B".)
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### `mod <= other`
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Returns `true` if `mod` is a subclass of `other` or is the same as `other`. Returns `nil` if there's no relationship between the two. (Think of the relationship in terms of the class definition: "class A < B" implies "A < B".)
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### `mod > other`
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Returns `true` if `mod` is an ancestor of `other`. Returns `nil` if there's no relationship between the two. (Think of the relationship in terms of the class definition: "class A < B" implies "B > A".)
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### `mod >= other`
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Returns `true` if `mod` is an ancestor of `other`, or the two modules are the same. Returns `nil` if there's no relationship between the two. (Think of the relationship in terms of the class definition: "class A < B" implies "B > A".)
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### `module <=> other_module`
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Comparison---Returns -1, 0, +1 or `nil` depending on whether `module` includes `other_module`, they are the same, or if `module` is included by `other_module`.
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Returns `nil` if `module` has no relationship with `other_module`, if `other_module` is not a module, or if the two values are incomparable.
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### `name`
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Returns the name of the module.
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### `singleton_class?`
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Returns `true` if the module is a singleton class.
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### `module_exec(arg...) {|var...| block } -> obj`
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### `class_exec(arg...) {|var...| block } -> obj`
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Evaluates the given block in the context of the class/module. The method defined in the block will belong to the receiver. Any arguments passed to the method will be passed to the block. This can be used if the block needs to access instance variables.
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```ruby
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class Thing
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end
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Thing.class_exec{
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def hello() "Hello there!" end
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}
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puts Thing.new.hello()
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```
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## Class Methods
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### `subclasses -> array`
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Returns an array of classes where the receiver is the direct superclass of the class, excluding singleton classes. The order of the returned array is not defined.
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```ruby
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class A; end
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class B < A; end
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class C < B; end
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class D < A; end
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A.subclasses #=> [D, B]
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B.subclasses #=> [C]
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C.subclasses #=> []
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```
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### `attached_object -> object`
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Returns the object for which the receiver is the singleton class. Raises a `TypeError` if the class is not a singleton class.
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```ruby
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class Foo; end
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Foo.singleton_class.attached_object #=> Foo
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Foo.attached_object #=> TypeError: not a singleton class
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Foo.new.singleton_class.attached_object #=> #<Foo:0x000000010491a370>
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TrueClass.attached_object #=> TypeError: not a singleton class
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NilClass.attached_object #=> TypeError: not a singleton class
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```
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