class Object # Returns true if this object is included in the argument. Argument must be # any object which responds to +#include?+. Usage: # # characters = ["Konata", "Kagami", "Tsukasa"] # "Konata".in?(characters) # => true # # This will throw an +ArgumentError+ if the argument doesn't respond # to +#include?+. def in?(another_object) another_object.include?(self) rescue NoMethodError raise ArgumentError.new("The parameter passed to #in? must respond to #include?") end # Returns the receiver if it's included in the argument otherwise returns +nil+. # Argument must be any object which responds to +#include?+. Usage: # # params[:bucket_type].presence_in %w( project calendar ) # # This will throw an +ArgumentError+ if the argument doesn't respond to +#include?+. # # @return [Object] def presence_in(another_object) self.in?(another_object) ? self : nil end end