Ruby中delegate的一些用法

classs Admin < activeRecord::Base
 
  delegate :firstname, :to => :user
  # 等价于
  # firstname => user.firstname

  # delegate :firstname, :to => :user, :prefix => true
  # 等价于 
  # user_firstname => user.firstname

  # delegate :firstname, :to => :user, :allow_nil => true, :prefix => true
  # 等价于 
  #  user_firstname => user.try(:firstname)


  # delegate :name, :to => "user.try(:editor)", :prefix => :editor
  # 等价于 
  # editor_name => user.try(:editor).name  #注意空异常

  # delegate :name, :to => "user.try(:editor)", :prefix => :editor, :allow_nil => true
  # 等价于 
  # editor_name => user.try(:editor).try(:name) 

end