Why I Like Interfaces

Our interactions with systems can all be described and/or defined by their interfaces. We’ve all found interfaces that are pleasantly intuitive (gumball machines) or frustratingly painfully (push doors that pull doors in disguise, Norman Doors). When developing software we take on the role of the interface designer and we have the chance to at least avoid making Norman Doors.

Guidelines

• Well defined behavior
• Avoid side effects
• Inputs are well specified
• Don’t change inputs
• Don’t change outputs
• Guides users to best outcomes
• Protects users from sharp edges and negative outcomes