Class Attributes and Method Kinds

Scenario: Every service shares the same category label but keeps its own status.

New words, in plain English

• Class attribute - data shared through the class
• Instance method - a method receiving self
• Class method - a method receiving cls, often an alternate constructor
• Static method - a namespaced function receiving neither automatically

Put shared constants on the class and per-object state on instances. @classmethod can construct from another representation. Use @staticmethod sparingly when a helper belongs conceptually to the class.

Analogy: A Python program is like a clear set of instructions for a careful helper: names label things, indentation groups steps, and errors explain where the helper became confused.

A small, real example

class Service:
    kind = "network"
    def __init__(self, name): self.name = name
    @classmethod
    def from_url(cls, url): return cls(url.split("//")[-1])

Tip: A mutable class attribute is shared by every instance, often accidentally.

Goal: Practice this idea in the py-small-class challenge at /labs/python. Fix the broken program, run it yourself, then use check to prove the real end state.