Should methods be inside classes? in Ruby

Question

I have coded more in Python but I am learning Ruby now. So I am trying to write a solution to create a family_tree and add and get relationships. The code below is of the file that contains the main function which is called from the command line. The below code works and solves the problem but I have written methods without classes. In python it is acceptable. Is is acceptable in ruby? Even though the code works is this how it is written in Ruby? Or does this need refactoring? If yes then please tell how?

#main_file.rb

require_relative 'family'
require_relative 'family_tree'
include FamilyTree
require_relative 'constants'
require_relative 'errors'
def is_valid_input(command)
 #User input Validation
 commands = command.split(' ')
 return false unless (commands && INPUT_FUNCTION_MAPPER.key?(commands[0]))
 return false if (commands[0] == "ADD_CHILD" && commands.length != 4)
 return true
end
def create_family_tree(family_tree)
 #Initializing the family
 family_name = family_tree[:name]
 members = family_tree[:members]
 family = Family.new(family_name)
 members.each do |name, gender, mother_name|
 family.add_member(name, gender, mother_name)
 end
 family
end
def execute_command(command, family)
 result = nil
 unless is_valid_input(command)
 raise InvalidParametersError, "Command is not valid"
 end
 command = command.split(" ")
 if command[0] == "ADD_CHILD"
 mother, name, gender = command[1..]
 result = family.add_member(name, gender, mother)
 end
 result
end
def main_method
 if ARGV.length != 1
 raise InvalidParametersError, "Please provide an input file"
 end
 input_file = ARGV[0]
 unless File.file?(input_file)
 raise InvalidParametersError, "Input file does not exist"
 end
 family = create_family_tree(FAMILYTREE)
 File.readlines(input_file).each do |line|
 line = line.strip
 puts execute_command(line, family)
 end
end
main_method()

This is executed as below:

ruby main_file.rb input.txt

• Cary Swoveland: A small thing caught my eye: the last three lines of the body of is_valid_input? would normally be written commands && INPUT_FUNCTION_MAPPER.key?(commands[0])) && (commands[0] != "ADD_CHILD" || commands.length == 4) (or the logical equivalent).

Answer 1

This "global function" style works for small scripts but isn't reusable.

A more practical problem with it is if you want to have state that is shared between functions, you don't have anywhere to store it (well, you could use global variables ($var), but that's prone to conflicts).

For a more encapsulated design, create a class that does the work and move the methods into the class. See for example definition and usage.