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Errors & debugging

Handle failures gracefully, raise helpful errors, and debug with confidence.

3 matches

How to Dump a Debugging Repr for Unknown Types in Python

Build a fallback repr that shows dataclass fields or object attributes for any value, handy when debugging unknown types.

debugging repr dataclasses

Python

import dataclasses
from typing import Any


@dataclasses.dataclass
class Sample:
    name: str
    values: list[int]


def dump_repr(obj: Any) -> str:
    """Return a concise but complete repr for debugging unknown types."""
    if dataclasses.is_dataclass(obj):
        fields = ", ".join(
            f"{field.name}={…

12 0 Open

Errors & debugging easy

How to Emit Deprecation Warnings in Python

Use the warnings module to mark legacy classes and methods as deprecated, letting users know to switch to newer APIs.

warnings deprecation debugging

Python

import warnings


class OldAPI:
    def __init__(self):
        warnings.warn(
            "OldAPI is deprecated; use NewAPI instead.",
            DeprecationWarning,
            stacklevel=2,
        )
        self.data = []

    def add(self, item):
        warnings.warn(
            "OldAPI.add() is deprecated; us…

14 0 Open

Errors & debugging easy

How to define an exception hierarchy for domain errors in Python

Create a custom exception hierarchy with a base DomainError class and specific subclasses to handle validation, not-found, permission, and concurrency errors cleanly in Python apps.

exceptions domain-errors error-handling

Python

class DomainError(Exception):
    """Base class for all domain errors."""
    pass

class ValidationError(DomainError):
    """Raised when input data fails validation rules."""
    pass

class NotFoundError(DomainError):
    """Raised when a requested entity does not exist."""
    pass

class PermissionDeniedError(Dom…

14 0 Open

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