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Errors & debugging

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

3 matches

How to Assert Preconditions with Descriptive Messages in Python

Use Python's assert statement with a custom message to validate function preconditions and fail fast with clear diagnostics.

assert debugging preconditions

Python

def divide(dividend, divisor):
    assert divisor != 0, f"Divisor must be non-zero, got {divisor!r}"
    return dividend / divisor


if __name__ == "__main__":
    print(divide(10, 2))
    try:
        divide(10, 0)
    except AssertionError as e:
        print(f"AssertionError: {e}")

16 0 Open

Errors & debugging easy

How to Record Last N Errors with a Ring Buffer in Python

Use collections.deque with maxlen to keep only the most recent N error messages while discarding older entries automatically.

ring-buffer deque error-handling

Python

import collections

class ErrorRecorder:
    def __init__(self, size):
        self.buffer = collections.deque(maxlen=size)

    def record_error(self, message):
        self.buffer.append(message)

    def get_errors(self):
        return list(self.buffer)

if __name__ == "__main__":
    recorder = ErrorRecorder(3)
 …

13 0 Open

Errors & debugging easy

How to Serialize an Exception to a JSON-Safe Dict in Python

Convert any Python exception into a JSON-safe dictionary with type, message, and the last few traceback lines for logging.

exceptions json logging

Python

import json
import traceback
from typing import Any


def exception_to_dict(exc: Exception) -> dict[str, Any]:
    """Convert an exception into a JSON-safe dictionary."""
    return {
        "type": type(exc).__name__,
        "message": str(exc),
        "traceback": traceback.format_exc().strip().split("\n")[-3:],
…

15 0 Open

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