As a backend developer, I sometimes help companies evaluate candidates by reviewing their recorded technical interviews. However, over time, I’ve noticed a deeply ingrained misconception. When discussing memory management or data streaming, many developers explicitly state:
"Iterators in Python are inherently eager. If you want true lazy loading or lazy evaluation, you have to use generators and the yield keyword."
This misconception is common. Many popular bootcamps and online courses introduce lazy evaluation exclusively through generators. Custom class-based iterators are usually skipped or dismissed as boilerplate-heavy OOP theory rarely used in production Python.
This confusion is further reinforced by two common educational simplifications:
The List vs. Generator Expression Analogy: Beginners are taught that square brackets [...] (list comprehensions) are eager and take up memory, while parentheses (...) (generator expressions) are lazy. This often creates a false binary mental model: "generators = lazy, everything else = eager."
