Ruby 元编程 方法

1.动态方法 （send && fine_method） --  动态派发 ， 动态创建，  动态内省 缩减代码

2.0.0p247 :071 >   class Computer
2.0.0p247 :072?>    def initialize(computer_id, data_source)
2.0.0p247 :073?>     @id = computer_id
2.0.0p247 :074?>     @data_source = data_source
2.0.0p247 :075?>     data_source.methods.grep(/^get_(.)_info$/) {
2.0.0p247 :076 >         Computer.define_component $1
2.0.0p247 :077?>       end
2.0.0p247 :078?>     
2.0.0p247 :079 >       def
2.0.0p247 :080 >         self.define_component(name)
2.0.0p247 :081?>       define_method(name)
2.0.0p247 :082?>        info = @data_source.send "get_#{name}_info", @id
2.0.0p247 :083?>        price = @data_source.send "get_#{name}_price", @id
2.0.0p247 :084?>       result = "#{name.capitalize} : #{info} ($#{price})"
2.0.0p247 :085?>       return "* {result}" if price >= 100
2.0.0p247 :086?>       result
2.0.0p247 :087?>       end
2.0.0p247 :088?>     end

2.0.0p247 :481 >   class SubClass
2.0.0p247 :482?>    define_method :method_added do |name|
2.0.0p247 :483 >        puts "# added a method #{name}"
2.0.0p247 :484?>     end
2.0.0p247 :485?>   end

2.0.0p247 :492 > SubClass.new.method_added "niaho"
# added a method niaho
 => nil 
2.0.0p247 :493 > 

2.method_missing() 方法

覆写 method_missing

2.0.0p247 :107 > 'to_aaaa'.to_s =~ /^to_(.*)/; p $1
"aaaa"
 => "aaaa" 
2.0.0p247 :108 > "aaaa".to_sym
 => :aaaa 
2.0.0p247 :109 >

2.0.0p247 :130 > p="aasfasfs.asfsa.asf".gsub('.','_')
 => "aasfasfs_asfsa_asf" 
2.0.0p247 :131 >  

幽灵方法

class Table
  def method_missing(id,*args,&block)
    return as($1.to_sym, *args,&block) if id.to_s =~ /^to_(.*)/
    return rows_with($1.to_sym => args[0]) if id.to_s =~ /^rows_with_(.*)/
    super  
  end
end

class MyOpneStruct
  def initialize
    @attributes = {}
  end

  def method_missing(name,*args)
    attribute = name.to_s
    if attribute =~ /=$/
      @attributes[attribute.chop] = args[0]
    else
      @attributes[attribute]
    end
  end
end

icecream = MyOpneStruct.new
icecream.flavor = "vanilla"
icecream.flavor