The first statement is false. It is not true
that because of pair programming, we need twice as many
developers. In fact that there is some evidence that even
though in pair programming we have two developers working together,
that the overall efficiency of the programmers is not really
affected by use of this practice. In XP, code is
rarely changed after being written. This is also definitely false.
In fact in XP there is a lot of emphasis
on change on the fact that the code can be changed,
it can be resigned, because of the fact when we do
that, we have a set of these cases that we can
use to check right away that the code still works as
expected. So again in XP, it's all about steering rather than
just driving down one fixed direction. And therefore, the code can
be changed. So this statement is false. It is definitely true
that XP follows the test driven development paradigm. In XP we first
write tests, and then we write the code, which is
exactly what TDD is about. It is not true that
the customer does not need to provide requirements in XP.
The customer does provide requirements in the form of user
stories, and the user stories are the starting point of
the development process. Finally, XP is definitely an iterative software
development process. In fact, we saw that XP is based
on subsequent iterations of the same cycle, in which we
select from a set of story cards, or user
stories, the stories that we want to implement in the
next iteration. Based on that we develop task cards,
and then we use the task cards to write this
case and then to write code. And we continue
this cycle in an iterative way until we are done
with all the story cards, and all the user
stories, so definitely XP is an iterative software development process.