Reusing Code
All developers write code (or should write code) with reuse in mind. The many reasons this is a good idea include:
Saving time—
If it is written once, don't write it again.
Easier maintenance—
Make a change in one place and any code that uses it gets that change automatically.
Easier debugging—
Fewer copies exist out there that will need to be fixed.
Group development—
Developers can share code more easily.