Renaming variables in vim

If I have a method definition like this:

def foo_bar(string)
  puts old_variable_name
end

foo_bar('hello')
foo_bar('goodbye')
foo_bar('au revoir)
foo_bar('auf Wiedersehen')
foo_bar('ciao')

To change all instances of foo_bar:

1. Put my cursor over the first instance
2. gd (or gD for global replacement)
3. c (change)
4. gn (new name)
5. ESC key
6. . to repeat the changes one by one.

Alternatively:

1. Put my cursor over the first instance
2. gd (or gD for global replacement)
3. c (change)
4. gn (new name)
5. ESC key
6. :%norm. to rename all occurences in the buffer.

Thus…

def bar_foo(string)
  puts old_variable_name
end

bar_foo('hello')
bar_foo('goodbye')
bar_foo('au revoir)
bar_foo('auf Wiedersehen')
bar_foo('ciao')