Errors & debugging
Handle failures gracefully, raise helpful errors, and debug with confidence.
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.
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)
…How to Use a Fallback Path with FileNotFoundError in Python
Read a primary file and fall back to a backup file when the first is missing, returning an empty string if both fail.
import pathlib
def read_config(path):
primary = pathlib.Path(path)
fallback = pathlib.Path("config_backup.json")
try:
with primary.open("r") as f:
return f.read()
except FileNotFoundError:
try:
with fallback.open("r") as f:
return f.read()
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Errors & debugging — Python code examples
What you will find here
This page collects errors & debugging snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
Samples vs tutorials and challenges
Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.