::MyClass Ruby 作用域运算符有什么作用? [英] What does ::MyClass Ruby scope operator do?

问题描述

::MyClass/MyModule 作用域运算符在 Ruby 中有什么作用，它的用途是什么?

What does the ::MyClass/MyModule scope operator do in Ruby, what is its purpose?

推荐答案

这在全局范围内显式引用 MyClass.如果全局作用域中有MyClass，SomeModule内部也有MyClass，则SomeModule内部引用MyClass会引用模块内部的MyClass，而不是全局MyClass.说 ::MyClass 明确引用全局范围内的 MyClass.

This explicitly refers to the MyClass in the global scope. If there is a MyClass in the global scope, but also a MyClass inside of SomeModule, referring to MyClass from inside of SomeModule will refer to MyClass inside of the module, not the global MyClass. Saying ::MyClass explicitly refers to the MyClass in the global scope.

class MyClass
  def self.something
    puts "Global MyClass"
  end
end

module SomeModule
  class MyClass
    def self.something
      puts "SomeModule::MyClass"
    end
  end

  print "From the module: "
  MyClass.something

  print "Explicitly using global scope: "
  ::MyClass.something
end

print "From the global scope: "
MyClass.something

print "Explicitly using module scope: "
SomeModule::MyClass.something

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