Public and Private interfaces

Sandi Metz in “Practical Object-Oriented Design in Ruby” has a great bullet list on what our methods communicate in our code.

Public interfaces

• expected to be invoked by others
• are safe for others to depend on
• have tests
• reveal primary responsibility

Private interfaces

• handle implementation details
• can change for some reason
• aren’t safe for others to depend on
• aren’t expected to be send by other objects