class Fred
        @@tags_connection = {
             :adapter  => "mysql",
             :username => "root",
             :password => "",
             :database => "INTERVIEW",
             :socket => "/var/run/mysqld/mysqld.sock"
          }
          def foo
            puts @@tags_connection[:database]
          end
        end

def Fred.foo
    class_variable_set(:@@tags_connection[:database], 'toto')
end
Fred.foo
Fred.new.foo