Question

我希望实现类似下面的内容。根据数组参数定义方法名称并调用它们。

arr = ['alpha', 'beta', 'gamma']

arr.each { |role|
  # If the method already exists don't define new
  if ! method_exist? "init_#{role}"
    define "init_#{role}"
      p "I am method init_#{role}"
    end
}

init_beta
init_gamma

编辑：如果这种方法已经存在，请不要定义新方法。

Answer 1

执行以下操作：

arr = ['alpha', 'beta', 'gamma']

arr.each do |role|
  # this code is defining all the methods at the top level. Thus call to 
  # `method_defined?` will check if any method named as the string argument 
  # is already defined in the top level already. If not, then define the method.
  unless self.class.private_method_defined?( "init_#{role}" )
    # this will define methods, if not exist as an instance methods on 
    # the top level.
    self.class.send(:define_method, "init_#{role}" ) do
      p "I am method init_#{role}"
    end
  end
end

init_beta # => "I am method init_beta"
init_gamma # => "I am method init_gamma"

查看private_method_defined和define_method的文档。

注意：我在顶层使用了private_method_defined?，您将定义的所有实例方法（在默认辅助功能级别使用def或define_method ），成为Object的私有实例方法。现在根据您的需要，您还可以相应地检查protected_method_defined?和public_method_defined?。

Ruby：基于变量值动态定义方法

1 个答案: