Here are some very useful tips for Emacs, regarding swapping.
If you have a text like the following and you want to change the order of the parameters for the foo function:
foo(First, Second) ->;
Just put the cursor on the comma or on the space between First and Second and press:
You will get the following:
foo(Second, First) ->;
Put the cursor at the beginning of the second line and press:
You will get: