Namespaces and Mixins | 易学教程

问题

I'm trying to clean up our namespaces. Basically our setup is somewhat like

class myClass
 include myModule1
 include myModule2

 @important_var   #critical instance variable

Basically @important_var is a telnet handler that almost all methods need to get at. This works fine with the way it is setup right now. Unfortunately myModule1 & myModule2 are getting huge. So I keep running into namespace collisions for the methods.

I'd love to access methods with a module wrapper eg:

myClass_instance.myModule1.a_method

But I can't figure out how to do this or some other cleaner name spacing idea?

回答1:

Based on the idea to build a naming convention for the methods inside the modules I prepared a automated version:

module MyModule1
  def m;  "M1#m  <#{@important_var }>";  end
  #method according naming convention
  def m1_action;  "M1#m1 <#{@important_var }>";  end
end

module MyModule2
  def m;  "M2#m  <#{@important_var }>";  end
  #method according naming convention
  def m2_action;  "M2#m2 <#{@important_var }>";  end
end

class MyClass
  #add prefix to each method of the included module.
  def self.myinclude( mod, prefix )
    include mod
    #alias each method with selected prefix
    mod.instance_methods.each{|meth|      
      if meth.to_s[0..prefix.size-1] == prefix
        #ok, method follows naming convention
      else #store method as alias
        rename = "#{prefix}#{meth}".to_sym
        alias_method(rename, meth)
        puts "Wrong name for #{mod}##{meth} -> #{rename}" 
      end
    }
    #define a method '<<prefix>> to call the methods
    define_method(prefix){ |meth, *args, &block | send "#{prefix}#{meth}".to_sym *args, &block }
  end
  myinclude MyModule1, 'm1_'
  myinclude MyModule2, 'm2_'
  def initialize
    @important_var   = 'important variable' #critical instance variable
  end
end

###################
puts "-------Test method calls--------"

m = MyClass.new
p m.m1_action
p m.m2_action

p m.m #last include wins

puts "Use renamed methods"
p m.m1_m
p m.m2_m
puts "Use 'moduled' methods"
p m.m1_(:m)
p m.m2_(:m)

myinclude includes the module and checks, if each method begins with a defined prefix. If not the method is defined (via alias). In addition you get a method called like the prefix. This method forwards the call to the original module-method. See example in the code end.

来源：https://stackoverflow.com/questions/7574445/namespaces-and-mixins

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ruby

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namespaces

mixins