Introduction One of the first code smells we encounter when working with an object-oriented language where everything is an object, or everything subclasses a common base class, or there are no static methods, is how OOP typically handles equality of objects. For value types such as integers and floating point numbers, it’s not controversial that we should be able to compare them and decide if they’re equal or not. Integers can be compared by bits, and data structures can be compared by descending into the structure and comparing elements.

Introduction If you are gainfully employed as a programmer, you have probably been forced to accept object-oriented programming into your life. When working with a language like Swift or C++ which doesn’t have garbage collection, you will end up in the debugger, trying to locate a strong reference cycle which has resulted in a memory leak. Or, you’re reviewing a Pull Request and notice that there is a cyclic relationship between some classes.

Introduction An object maintains a reference/pointer to another object so it can call a method or access a property. References are called strong if the relationship between the objects is one of ownership, and weak or unowned if it the object containing the reference does not own the object being referred to. In languages like Swift, Objective-C, and C++, it’s required that we don’t create cycles of strong references, or we get memory leaks.