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require 'reek/smells/smell'

module Reek
  module Smells

    #
    # Control Coupling occurs when a method or block checks the value of
    # a parameter in order to decide which execution path to take. The
    # offending parameter is often called a Control Couple.
    # 
    # A simple example would be the <tt>quoted</tt> parameter
    # in the following method:
    # 
    #  def write(quoted)
    #    if quoted
    #      write_quoted(@value)
    #    else
    #      puts @value
    #    end
    #  end
    # 
    # Control Coupling is a kind of duplication, because the calling method
    # already knows which path should be taken.
    # 
    # Control Coupling reduces the code's flexibility by creating a
    # dependency between the caller and callee:
    # any change to the possible values of the controlling parameter must
    # be reflected on both sides of the call.
    # 
    # A Control Couple also reveals a loss of simplicity: the called
    # method probably has more than one responsibility,
    # because it includes at least two different code paths.
    #
    class ControlCouple < Smell
      def initialize(context, args)
        super
        @args = args
      end

      def recognise?(cond)
        @couple = cond
        cond[0] == :lvar and @args.include?(@couple[1])
      end

      def detailed_report
        "#{@context} is controlled by argument #{Printer.print(@couple)}"
      end
    end

  end
end

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
reek-0.3.1	lib/reek/smells/control_couple.rb