class Service: def __init__(self, logger): self.logger = logger # Injected dependency def perform_action(self): self.logger.log("Action performed") Use code with caution. Conclusion
Python resolves method lookups in multiple inheritance hierarchies using the C3 Linearization algorithm.
The following high-quality topics are central to the course and can serve as the foundation for study notes or a research summary:
If you implement __repr__ but not __str__ , Python falls back to __repr__ . Always implement __repr__ first. python 3 deep dive part 4 oop high quality
super() does not just call the parent class. It calls the next class in the MRO chain . This allows cooperative multiple inheritance to work.
The dynamic nature of __dict__ consumes significant memory. If you are creating millions of instances, you can optimize memory by using __slots__ . This tells Python to use a static array for attributes instead of a dynamic dictionary.
bundles data and methods within a single unit (a class) and protects internal state from unintended interference. class Service: def __init__(self, logger): self
__init__(self, ...) is an instance method responsible for that instance once it has been created. Practical Applications: Singletons and Immutability
Fred Baptiste, a PhD in mathematics with over 25 years of professional programming experience .
: Distinguishing between instance, class, and static methods, and when to use each effectively. Always implement __repr__ first
Introduced in Python 3.7, dataclasses provide a decorator and functions for automatically adding generated special methods like __init__() and __repr__() to user-defined classes. They are not a replacement for full-featured classes but are a massive productivity boost for classes that primarily store data.
Subtypes must be substitutable for their base types without altering program correctness. If a function expects a Rectangle , passing a Square (which inherits from Rectangle ) should work correctly. The classic "Square-Rectangle problem" illustrates how violating LSP—by overriding set_width and set_height inappropriately—leads to subtle bugs.
class Validator(ABC): @abstractmethod def validate(self, value): pass