Methods in ruby dont change variables -

i'm new ruby , new programming in general. have piece of code in standalone ruby script reads data yaml file , assigns data variable in method. done in method. outside definition of method, call method , print value of variable assigned. but, uh oh, value of variable assigned in method nil... why? has object oriented programming assume. can elaborate?

below code. thank in advance.

#!/usr/bin/env ruby  require 'pg' require 'yaml'  source_connection=nil  def load_configurations     file_name = nil      argv.each do|a|       file_name = "#{a}"     end     dest_options = yaml.load_file(file_name)     source_connection = dest_options['dest_name'] end  load_configurations()  puts source_connection  #####  returns nothing. why? ##### 

in ruby, in languages (all know @ least, javascript may exception) there concept called visibility scopes.

there 4 scopes in ruby:

• global scope
• class scope
• method scope
• block scope

what means in practice local variable defined ex. in method visible in method unless explicitly pass in (with method/block call param) or down (with return) call stack.

in case happens outside method assign source_connection nil, refer same var name in different scope assigned there. ruby way of solving either define instance variable (@source_connection) or explicitly pass variable method , return it.

pro tip: in ruby last evaluation gets returned default don't need explicitly write return source_connection.

edit:
class instance , instance variables things little more complicated best if point in direction of metaprogramming ruby book lays out topics.

edit2:
rewrite suggestion (with little style change - method definition it's add parentheres no matter of there params or not. call on other hand may omit if there's none or single param - depends on personal taste ;) changed indent 2 spaces - think it's commonly used.

#!/usr/bin/env ruby  require 'pg' require 'yaml'  def load_configurations()   file_name = nil    argv.each do|a|     file_name = "#{a}"   end   dest_options = yaml.load_file(file_name)   dest_options['dest_name'] # ruby return last evaluation end  source_connection = load_configurations  puts source_connection # print expect