D.R.Y.is don't repeat yourself.W.E.T.is write everything twice.- Prefer dry code to wet code.
Dry code appears in the code base one and only one time. Code that appears more than once it is not dry, it is wet.
When code is repeated [2, 3, ...n] times, it creates two code liabilities:
- Maintainence - a change to dry code requires only one update; the change is isolated to one location in the code base. A change to wet code requires that all instances of the code snippet be updated, a tedious and potentially time consuming task when the repeated code is pervasive throughout the code base. A project-wide search and replace may help find all instances, but requires additional maintainence effort.
- Bugs - moreover, wet code can be highly error prone. A lurking instance of wet code that was not discovered when a maintainence update ocurred exposes the developer to risk code bugs stemming from unanticipated behavior.