class - Modules and classes in Ruby. Contradictions? -

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according rubymonk section 8.1 modules hold behavior , not state , classes can hold behavior , state.

yet modules super-class of classes in ruby. how can be?

oh brother, , if forget module/class instance variables , module/class methods, can't classes hold state--because it's instances of classes hold state. classes hold list of instance methods. whole section on classes technically wrong too.

the bottom line 99.99% of things in ruby objects, , object can hold state. class object(as producer of objects), module object(but not producer of objects), , instances of classes objects.

i suggest not worry state. concentrate on fact modules can used 2 things:

1) namespace:

module myfunctions   def myfunctions.puts(str)  #...or: def self.puts(str)     kernel.puts "***" + str    end end  puts 'hello' myfunctions.puts 'hello'  --output:-- hello ***hello

2) package of methods included, e.g. in class:

module animaltricks   def speak     puts @noise   end end  class dog   include animaltricks    def initialize     @noise = "woof"   end  end   class mouse   include animaltricks    def initialize     @noise = "sqeak"   end  end  dog.new.speak mouse.new.speak  --output:-- woof sqeak

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