Staticmethod vs Classmethod

Choosing the Right Method Type

• instance method: uses self and instance state
• @classmethod: uses cls, often as alternate constructor
• @staticmethod: utility scoped to a class, no self/cls

Alternate Constructor

class RetryPolicy:
    def __init__(self, retries: int) -> None:
        self.retries = retries

    @classmethod
    def from_env(cls, env: dict) -> "RetryPolicy":
        value = int(env.get("RETRIES", "2"))
        return cls(retries=value)

Static Utility

class Urls:
    @staticmethod
    def join(base: str, path: str) -> str:
        return base.rstrip("/") + "/" + path.lstrip("/")

Operational Checklist

• Use @classmethod for factories and alternate constructors.
• Use @staticmethod sparingly; prefer module-level functions if no class context is needed.
• Keep method types consistent across similar classes.

Failure Modes

• Factory confusion: mixing constructors and factories inconsistently complicates usage.
• Overusing staticmethods: classes become namespaces without clear responsibility.