Refactoring: Improving the Design of Existing Code (Addison-Wesley Signature Series (Fowler))

by Martin Fowler

When we modularize a program, we are trying to separate the code into zones to maximize the interaction inside a zone and minimize interaction between zones. A classic case of Feature Envy occurs when a function in one module spends more time communicating with functions or data inside another module than it does within its own module. We’ve lost count of the times we’ve seen a function invoking half-a-dozen getter methods on another object to calculate some value. Fortunately, the cure for that case is obvious: The function clearly wants to be with the data, so use Move Function (198) to get it there. Sometimes, only a part of a function suffers from envy, in which case use Extract Function (106) on the jealous bit, and Move Function (198) to give it a dream home.