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Errors & debugging

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

3 matches

How to Print an Exception Chain in Python for Debugging

A helper that walks an exception's __cause__ and __context__ chain, printing each level with indentation to make debugging nested errors clearer.

exception-chain debugging traceback

Python

import sys
import traceback

def pretty_exception_chain(exc):
    """Print the full exception chain with cause/context details."""
    chain = []
    current = exc
    seen = set()
    
    while current is not None and id(current) not in seen:
        seen.add(id(current))
        chain.append(current)
        curren…

11 0 Open

Errors & debugging medium

How to Re-raise Exceptions with 'raise from' in Python

Shows how to re-raise an exception with explicit context chaining using the 'raise ... from ...' syntax, so the original cause is preserved for debugging.

exceptions raise-from error-handling

Python

def divide_with_chain(a, b):
    try:
        result = a / b
        return result
    except ZeroDivisionError as original_error:
        # Re-raise with explicit chaining context
        raise ValueError("Cannot divide by zero") from original_error

def explain_chain():
    try:
        divide_with_chain(10, 0)
    …

12 0 Open

Errors & debugging medium

How to attach a request ID to exception messages in Python

This code shows how to enrich exception messages with contextual request IDs using context variables, making error logs more traceable across concurrent requests.

contextvars exception-handling logging

Python

import logging
from contextvars import ContextVar

request_id_var = ContextVar("request_id", default="unknown")

def add_request_id(exc: Exception) -> Exception:
    exc.args = (f"request_id={request_id_var.get()} | {exc.args[0]}" if exc.args else f"request_id={request_id_var.get()}",) + exc.args[1:]
    return exc

d…

12 0 Open

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