We Reinvented OOP by Making a Sandwich (Before Writing Any Code)

The author recounts a unique approach to teaching Object-Oriented Programming (OOP) that eschews code in favor of conceptual understanding. By removing syntax and focusing on the problem-solving foundation first, a software apprentice named John crafted an algorithm to guide an autonomous robot in assembling a cheese sandwich using only basic objects: bread, butter, a knife, a plate, and cheese. This exercise highlighted several key concepts in OOP:

First, it illustrated the importance of precise verbs and the dangers of ambiguity—when the apprentice's robot "takes" butter, it's unclear whether this means slicing, scooping, or stabbing. This led to the realization that software requirements must be unambiguous to avoid defects. The author also pointed out the fallacy of assuming mathematical properties like commutativity apply to physical assembly, a lesson that prevents issues in real-world code.

Next, they introduced the idea of state transitions, comparing bread becoming buttered to a software object undergoing a state change. This concept is crucial for understanding how actions affect objects in computer science. The apprentice then applied this to a banking scenario, discovering Command-Query Separation (CQS), where some actions, like checking an account balance, return information without changing the object's state—akin to a method that simply reads data.

Finally, the author addressed scalability with a scenario involving 100 cars in a racing simulation. The apprentice grasped the necessity of a class as a template, defining shared characteristics and behaviors for multiple instances, or objects. This insight led to the realization of object-oriented principles: classes are blueprints for objects, with properties (state) and methods (behaviors).

The apprentice's mental model, culminating in C# syntax, demonstrated that true OOP comprehension comes from first grasping concepts before translating them into code.