This mental castle is a walk through Onni, SLU, from the Pickleball Gym to the Fairview Postboxes.

Design Principles

• Pickleball Gym Complexity is incremental: you have to sweat the small stuff.
• You need players Working code isn’t enough.
• Shitty net Make continual small investments to improve system design.
• Serve deep Modules should be deep.
• Couch area Interfaces should be designed to make the most common usage as simple as possible.
• Music/Toilet/Main Door Different layers should have different abstractions.
• Hallway -1 Outside Gym Pull complexity downward.
• Non-closing door under Stairs Define errors (and special cases) out of existence.
• Stairs Design it twice.
• Token Comments should describe things that are not obvious from the code.

Red Flags

• Onni Hallway Shallow Module: the interface for a class or method isn’t much simpler than its implementation.
• Renters Office Information Leakage: a design decision is reflected in multiple modules.
• Seattle Times Temporal Decomposition: the code structure is based on the order in which operations are executed, not on information hiding.
• Hotel Lobby Overexposure: An API forces callers to be aware of rarely used features in order to use commonly used features.
• Cycle Room Repetition: a nontrivial piece of code is repeated over and over.
• Gym Room Pass-Through Method: a method does almost nothing except pass its arguments to another method with a similar signature.
• Swimming Pool Special-General Mixture: special-purpose code is not cleanly separated from general purpose code.
• Conference Rooms Conjoined Methods: two methods have so many dependencies that its hard to understand the implementation of one without understanding the implementation of the other.
• Tapping Token Twice to get to Fairview Comment Repeats Code: all of the information in a comment is immediately obvious from the code next to the comment.
• Front Desk Lady Vague Name: the name of a variable or method is so imprecise that it doesn’t convey much useful information.
• Entrance to Fairview Hard to Describe: in order to be complete, the documentation for a variable or method must be long.
• Postbox Name Tag Trick Nonobvious Code: the behavior or meaning of a piece of code cannot be understood easily.