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How to parse a traceback to get the last frame in Python
Extracts the innermost frame's file, line, and function name from a Python traceback object.
import sys
import traceback
def parse_traceback_last_frame(exc_info):
"""Return the file, line, and function of the last (innermost) frame."""
_, _, tb = exc_info
last_tb = tb
while last_tb.tb_next is not None:
last_tb = last_tb.tb_next
filename = last_tb.tb_frame.f_code.co_filename
l…How to Generate Beautiful QR Codes with Embedded Logos in Python
Generate a high-error-correction QR code and paste a logo image in the center to create a branded, scannable QR code.
import qrcode
from PIL import Image
def generate_qr_with_logo(data, logo_path, output_path):
qr = qrcode.QRCode(
version=1,
error_correction=qrcode.constants.ERROR_CORRECT_H,
box_size=10,
border=4,
)
qr.add_data(data)
qr.make(fit=True)
qr_img = qr.make_image(fill_c…Tail last N lines of growing log file in Python
Prints the last n lines of a log file and follows new content appended to it, polling for size changes.
import time
from pathlib import Path
def tail_log(file_path, n=10, poll_interval=1.0, timeout=10):
"""
Print the last n lines and follow new lines appended to a growing log file.
"""
path = Path(file_path)
# Read the last n lines from the current file
with path.open("r", encoding="utf-8") as f…LRU Cache with OrderedDict in Python
Implement an LRU cache using collections.OrderedDict to track insertion order and evict the least-recently-used item when capacity is exceeded.
from collections import OrderedDict
class LRUCache:
def __init__(self, capacity):
self.capacity = capacity
self.cache = OrderedDict()
def get(self, key):
if key not in self.cache:
return -1
self.cache.move_to_end(key)
return self.cache[key]
def put(sel…Circuit Breaker Pattern in Python for LLM API Calls
Implements a circuit breaker class that wraps LLM client calls to fail fast when the service is degrading, then recover automatically after a timeout.
import time
class CircuitBreaker:
def __init__(self, failure_threshold=3, recovery_timeout=5):
self.failure_threshold = failure_threshold
self.recovery_timeout = recovery_timeout
self.failure_count = 0
self.state = "closed"
self.last_failure_time = None
def call(self, …Detect Circular Imports Across Python Projects Automatically
This script walks through all .py files in a directory, builds an import graph, and uses depth-first search to find cycles—printing each circular dependency chain.
import ast
import sys
from pathlib import Path
from collections import defaultdict, deque
def find_imports(filepath):
"""Return set of module names imported by a Python file."""
imports = set()
try:
with open(filepath) as f:
tree = ast.parse(f.read())
except (SyntaxError, UnicodeDe…Find Dead Code in a Python Project Using AST
Walk a project tree, parse every Python file with ast, and list defined functions that are never called anywhere.
import ast
import os
import sys
def find_dead_code(project_path):
defined_functions = {}
called_functions = set()
for root, dirs, files in os.walk(project_path):
for file in files:
if file.endswith('.py'):
filepath = os.path.join(root, file)
with open(f…Find Unused Python Packages Automatically
Scan a Python project's source files for imports and list installed packages not imported anywhere.
import pkg_resources
import ast
import os
import sys
from pathlib import Path
def find_imports_in_project(project_dir="."):
imports = set()
for py_file in Path(project_dir).rglob("*.py"):
try:
with open(py_file, "r") as f:
tree = ast.parse(f.read())
for node in …Generate Beautiful Project Documentation from Python Source Code Automatically
Automatically generate a markdown summary of function docstrings from any Python source file using the AST module.
import ast
import inspect
from pathlib import Path
def extract_docstrings_from_file(filepath):
"""Parse a Python file and collect function docstrings."""
source = Path(filepath).read_text()
tree = ast.parse(source)
docs = []
for node in ast.walk(tree):
if isinstance(node, (ast.FunctionDef…How to Build a Python Tool That Finds Trending Open Source Projects Daily
A Python script that queries the GitHub Search API to fetch the top 5 trending repositories created in the last day, sorted by stars, with optional language filtering.
import requests
import json
import datetime
def fetch_trending_projects(language: str = "", since: str = "daily"):
url = "https://api.github.com/search/repositories"
date_limit = (datetime.date.today() - datetime.timedelta(days=1)).isoformat()
query = f"created:>{date_limit} language:{language}" if langua…How to Generate a Dependency Graph for Python Projects
This script walks through a Python project directory, parses each .py file's imports, and prints a dependency graph showing which modules depend on which other modules.
import os
import ast
from pathlib import Path
from collections import defaultdict
def get_imports(filepath):
with open(filepath) as f:
try:
tree = ast.parse(f.read())
except SyntaxError:
return []
imports = []
for node in ast.walk(tree):
if isinstance(node, …How to Monitor Website Content Changes in Python
This script fetches a webpage's content, computes its SHA-256 hash, and compares it with the last stored hash to detect and alert on changes.
import time
import hashlib
import requests
from pathlib import Path
def fetch_content_hash(url: str) -> str:
response = requests.get(url, timeout=10)
response.raise_for_status()
return hashlib.sha256(response.text.encode()).hexdigest()
def monitor_website(url: str, check_interval: int = 60):
hash_fil…How to check Python files for common coding mistakes
Walks a directory tree parsing each .py file with ast, reporting empty functions, bare try blocks, too many parameters, and empty classes.
import ast
import os
import sys
def check_file(filepath):
try:
with open(filepath) as f:
code = f.read()
tree = ast.parse(code, filename=filepath)
except SyntaxError as e:
print(f"{filepath}: SyntaxError: {e.msg}")
return
issues = []
for node in ast.wal…Normalize Timestamps to UTC DateTime in Python
Convert timestamps in multiple formats to UTC-aware datetime objects using datetime.strptime and astimezone.
from datetime import datetime, timezone
raw_timestamps = [
"2024-01-15 14:30:00+02:00",
"17/05/2024 09:15:00 -0500",
"2024-03-01T22:45:00Z",
"2024-06-20 08:00:00+09:30"
]
def parse_and_convert(ts: str) -> datetime:
normalized_ts = ts.strip().replace("Z", "+00:00")
formats = [
"%Y-%m-%…Mock Google Pub/Sub publish and pull in Python
A lightweight in-memory mock of Google Pub/Sub with publisher/subscriber classes to test topic-based fan-out and message pulling without real infrastructure.
import json
import time
from collections import deque
from dataclasses import dataclass, field
from typing import Any, Callable
@dataclass
class Message:
data: str
attributes: dict[str, str] = field(default_factory=dict)
message_id: str | None = None
ack_id: str | None = None
class MockPublisher:
…Mock Route53 change_resource_record_sets in Python
This code demonstrates how to mock AWS Route53 change_resource_record_sets API calls using the botocore Stubber, allowing you to test DNS update logic without touching real infrastructure.
import boto3
from botocore.exceptions import ClientError
def mock_change_resource_record_sets():
"""Demonstrates Route53 change_resource_record_sets with a mock client."""
# Create a mock Route53 client
route53 = boto3.client('route53', region_name='us-east-1',
aws_access_key_id…How to Parse JSON Files in Parallel with Python ThreadPoolExecutor
Load and transform JSON records from multiple files concurrently using ThreadPoolExecutor for faster I/O-bound parsing.
import time
from concurrent.futures import ThreadPoolExecutor
import json
def load_json_file(path):
with open(path, 'r') as f:
return json.load(f)
def transform_record(record):
record['full_name'] = f"{record.pop('first_name', '')} {record.pop('last_name', '')}".strip()
record['score'] = int(reco…How to Encode and Decode Avro Data in Python (Roundtrip)
Serialize a Python dict to Avro binary bytes and decode it back using the fastavro-compatible avro library.
import io
import json
from avro.schema import parse
from avro.io import DatumWriter, DatumReader, BinaryEncoder, BinaryDecoder
def avro_roundtrip(schema_json, data):
schema = parse(json.dumps(schema_json))
bytes_writer = io.BytesIO()
encoder = BinaryEncoder(bytes_writer)
writer = DatumWriter(schema)
…How to Implement At-Least-Once Delivery with Acknowledgment in Python
This code demonstrates a mock message broker with at-least-once delivery, including retry logic and acknowledgment after successful processing.
import time
import uuid
from collections import deque
class MockMessageBroker:
def __init__(self):
self.queue = deque()
self.acked = set()
def publish(self, payload: str) -> str:
msg_id = str(uuid.uuid4())
self.queue.append((msg_id, payload))
return msg_id
def po…How to Implement an LFU Cache in Python
Implement a Least Frequently Used (LFU) cache with frequency tracking dictionaries to evict the least accessed items when capacity is reached.
class LFUCache:
def __init__(self, capacity: int):
self.capacity = capacity
self.data = {}
self.freq = {}
self.min_freq = 0
def get(self, key: int) -> int:
if key not in self.data:
return -1
self._increment_freq(key)
return self.data[key]
…At Least Once with Idempotent Consumer in Python
Implements a thread-safe idempotent consumer that processes each unique message exactly once, even when a producer sends duplicates under an at-least-once delivery model.
import threading
import time
import uuid
from collections import Counter
class IdempotentConsumer:
def __init__(self):
self.processed = set()
self._lock = threading.Lock()
def consume(self, message_id, payload):
with self._lock:
if message_id in self.processed:
…How to Cap Retry Attempts in Python with a Decorator
Build a reusable retry decorator that caps attempts, adds delays, and lets flaky services fail fast instead of hanging.
import random
from functools import wraps
from time import sleep
def retry(max_attempts, delay=0.1):
def decorator(func):
@wraps(func)
def wrapper(*args, **kwargs):
attempts = 0
while attempts < max_attempts:
try:
return func(*args, **kw…How to Implement a Circuit Breaker in Python
A Python dataclass that provides circuit breaker logic with closed, open, and half-open states to fail fast on repeated errors.
from dataclasses import dataclass
from datetime import datetime, timedelta
import time
@dataclass
class CircuitBreaker:
failure_threshold: int = 3
timeout_seconds: float = 5.0
failures: int = 0
state: str = "closed"
last_failure: datetime = None
def call(self, func):
if self.state ==…Implement a Circuit Breaker Pattern in Python
This code implements a simple circuit breaker that opens after a threshold of consecutive failures, causing subsequent calls to fail fast without invoking the underlying function.
class CircuitBreaker:
def __init__(self, failure_threshold=3):
self.failure_threshold = failure_threshold
self.failure_count = 0
self.open = False
def call(self, func, *args, **kwargs):
if self.open:
raise RuntimeError("Circuit is open - failing fast")
try:
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