SE (M) 2017-2018 Lab 5: Design Principles
Revision: v20180502a
We recommend collaborating in pairs.
Overview
You’ve been hired by the startup ExamMarkr to refactor their existing code base. They shipped
their product for enrollment season, but in the rush to get the product shipped the code is
terrible to work on. Now they’re struggling to add features that let you add a student’s mark for
a particular course. You’ll first identify the poor choices made by the existing developers,
refactor the code so that it is easier to maintain, then add in this missing functionality.
Identify coupling and cohesion
Read through and analyze the code. Try to identify where there are examples of coupling and
cohesion. In particular, note which type of coupling and cohesion is present in the existing
code. You may find it useful at this stage to quickly sketch out a UML diagram, but don’t spend
time making this look pretty.
Plan the solution
Now that you’ve noticed some problems with the existing code, plan out what needs to be
changed in order to reduce coupling and increase cohesion. Again, drawing out a quick UML
diagram is useful. Are your planned changes invoking a particular design pattern?
Refactor the code
Now refactor the code to your design. This may take quite some time, so don’t get too bothered
if you don’t finish it in the lab.