some ruby language exercise

exp.rb

def call_block
  puts "before call"
  yield
  yield
  puts "after call"
end

call_block{ puts "call" } #before call\ncall\ncall\nafter call


def args(*args)
  puts *args.join("-")
end

args "12","123","1234" #=> 12-123-1234


def block_args
  if block_given?
    puts yield 3
  end
end

block_args{ |x| x+3 } #=> 6


def block_args0(&block)
  puts block.call(3)
end

block_args0{ |x| x+4 } #=> 7

class Array
	
  def each0		
    if block_given?
      for x in self
        yield x
      end
    end
  end
	
  def each1(&block)
    self.each do |x|
      if x.class == Array
        x.each &block
      else 
      	block.call x
      end
    end
  end
	
  def sum0
    @sum = 0
    if block_given?
      for x in self
        @sum += yield x
      end
    end
    @sum
  end
end

[1,2,3].each0{|x| puts "x: #{x}"} #=> x: 1\nx: 2\nx: 3
[1,2,[3,3],4].each1{ |x| puts "x: #{x}"} #=> x: 1\nx: 2\nx: 3\nx: 3\nx: 4
puts [1,2,4].sum0{ |x| x%2==0 ? x : 0  } #=> 6


module Mix_thing
  def shut_up
    puts "mix mix mix"
  end
end
	
class Mix
  include Mix_thing
end

mix = Mix.new
mix.shut_up #=> mix mix mix


class Object
  define_method(:meta) do |*args|
    args.each{|c| puts c} #=> com\nnet
  end
end

class MetaO
  meta :com, :net 
end