Open minds leads to freedom

Some weeks ago I started doing pair programming with some co-workers basically for two things:

1. code some tasks of an user story
2. get familiar with a new software code base

I haven’t had an opportunity to put this technique in practice a lot before, but I can say it was extremely important and benefit for the project. Sometimes I was the driver and sometimes I was the observer. The driver is the person who starts coding and the observer is who starts doing the code review. That point is important: code review.

Pair programming encourages the review of the code. Perhaps you won’t have an opportunity to refactor some code as you have when you are pairing with someone. I think code reviews are important because:

• Reviews increase code quality, because there are 2 people thinking at the same task at the same time.
• Refactoring areas arise in the design where improvements are needed
• When you have the strong support of an IDE (as Eclipse), some refactorings (extract method, extract class, introduce parameter) are highly automated
• Code is more read than written, two people reading the code can understand a lot more about the code base
• New ideas arise because of different point of views
• Questions can be solved by the sum of knowledge of the code base

And you? What’s your experience with pair programming?

Reading Michael Feathers’ ‘Working Effectively With LegacyCode’, I found quite interesting his heuristics to trace propagation of effects to code:

1. Identify a method that will change.
2. If the method has a return value, look at its callers.
3. See if the method modifies any values. If it does, look at the method that use those values, and the methods that use those methods.
4. Make sure you look for superclasses and subclasses that might be users of these instance variables and methods also.
5. Look at parameters to the methods. See if they or any objects that their methods return are used by the code that you want to change.
6. Look for global variables and static data that is modified in any of the methods you’ve identified.