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Automatically Detect Weak Passwords from Large Password Lists in Python
This Python script identifies weak passwords from a list by checking length, common patterns, sequential characters, and uniform characters, returning those that fail the security checks.
import re
COMMON_PASSWORDS_FILE = "common_passwords.txt"
def is_weak(password):
# Check length
if len(password) < 8:
return True
# Check for common patterns
if password.lower() in {"password", "123456", "qwerty", "letmein", "admin", "welcome"}:
return True
# Check for sequential c…How to Detect PII in Documents Using Python
Use regex patterns to automatically detect emails, phone numbers, SSNs, and credit card numbers in text documents.
import re
from typing import List, Dict
def detect_pii(text: str) -> Dict[str, List[str]]:
patterns = {
"email": r"[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}",
"phone": r"\(?\d{3}\)?[-.\s]?\d{3}[-.\s]?\d{4}",
"ssn": r"\b\d{3}-\d{2}-\d{4}\b",
"credit_card": r"\b\d{4}[- ]?\d{4}[-…How to Use Optional Return in Python Instead of Raising Exceptions
A Python function returns None for missing dictionary keys instead of raising KeyError, enabling graceful lookup handling with type hints.
from typing import Optional
def find_user(users: dict, user_id: int) -> Optional[dict]:
"""
Look up a user by ID. Returns the user dict if found,
otherwise returns None instead of raising KeyError.
"""
return users.get(user_id)
def main() -> None:
users = {
1: {"name": "Alice", "ema…Composition over Inheritance: How to Build a Wallet Account in Python
Demonstrates composition by wrapping a WalletAccount class in an AuditedWallet decorator-like class to add behavior without changing the original class.
class WalletAccount:
def __init__(self, owner, balance=0.0):
self.owner = owner
self.balance = balance
def deposit(self, amount):
if amount <= 0:
raise ValueError("Deposit must be positive")
self.balance += amount
return self.balance
def withdraw(self, …Python Factory Method: Create Shapes by Type String
A factory method that maps a type string to a concrete shape class and returns an instance, with runtime error handling.
class Shape:
def draw(self):
raise NotImplementedError
class Circle(Shape):
def draw(self):
return "Drawing a circle"
class Square(Shape):
def draw(self):
return "Drawing a square"
class Triangle(Shape):
def draw(self):
return "Drawing a triangle"
class ShapeFact…How to Generate Git LFS Extension Patterns in Python
This script builds mock Git LFS file patterns for common geospatial extensions and filters them based on compression suffixes.
import itertools
import re
LFS_EXTENSIONS = {".csv", ".geojson", ".tif", ".shp", ".gpkg"}
def build_mock_lfs_pattern(base_name="data_usgs_lidar"):
patterns = []
for ext in sorted(LFS_EXTENSIONS):
for variant in (("", ".lz4"), (".compressed",), (".b", ".a"), ("_v1", ".zip")):
full_pattern …How to detect secrets in git history with Python
Scan a git history export file for common secret patterns using regex and Python.
import re
from pathlib import Path
def scan_history_for_secrets(history_file: str) -> list:
"""Scan a git history export for potential secrets using regex patterns."""
patterns = {
"AWS Access Key": r"AKIA[0-9A-Z]{16}",
"GitHub Token": r"gh[pousr]_[0-9A-Za-z]{36,255}",
"Private Key": …How to Create a Mock STS AssumeRole Credentials Dict in Python
Build a realistic AWS STS AssumeRole response dict with temporary credentials, expiry time, and assumed role ARN for local testing.
import json
from datetime import datetime, timedelta, timezone
def mock_sts_credentials(role_arn, session_name, duration=3600):
now = datetime.now(timezone.utc)
expiration = now + timedelta(seconds=duration)
credentials = {
"Credentials": {
"AccessKeyId": "ASIAEXAMPLEACCESSKEY",
…Dependency Injection in Python for Testability
Inject a config dependency into a service so you can swap a real environment-based config for a fake one in tests.
import os
class Config:
"""Simple config loader that can be easily faked in tests."""
def get(self, key, default=None):
return os.environ.get(key, default)
class UserService:
def __init__(self, config):
self.config = config
def get_timeout(self):
return int(self.config.get(…How to Build an Append-Only Event Store in Python
Implement a simple append-only event store class that stores events in a list and supports retrieval by index range.
class EventStore:
def __init__(self):
self._events = []
def append(self, event):
"""Append an event to the store."""
self._events.append(event)
def get_events(self, start=0, end=None):
"""Return events from start index to end (exclusive)."""
return self._events[sta…How to Build an MVP Presenter View Mock in Python
A minimal MVP (Model-View-Presenter) mock showing a Presenter controlling a SlideDeck model with slide navigation and typed state via dataclasses.
from dataclasses import dataclass, field
from typing import List
@dataclass
class SlideDeck:
title: str
slides: List[str] = field(default_factory=list)
current_index: int = 0
def next_slide(self) -> str:
if self.current_index < len(self.slides) - 1:
self.current_index += 1
…How to Implement a Data Helper Class in Python
Build a beginner-friendly DataHelper class using dataclasses and key system design patterns like Command, Strategy, and Map.
from __future__ import annotations
from dataclasses import dataclass, field
from typing import Any, Dict, List, Optional
@dataclass
class DataHelper:
"""A beginner-friendly data utility with common system design patterns."""
data: List[Dict[str, Any]] = field(default_factory=list)
def add_record(self, r…How to Implement a Factory Method by Type String in Python
A factory method maps a type string to a class, creating and returning the appropriate object instance while handling unknown types gracefully.
class Animal:
def speak(self):
raise NotImplementedError
class Dog(Animal):
def speak(self):
return "Woof!"
class Cat(Animal):
def speak(self):
return "Meow!"
class AnimalFactory:
@staticmethod
def create(animal_type: str) -> Animal:
animal_types = {
…How to Implement a Simple Event Bus in Python
Create a publish-subscribe event bus using dataclasses and defaultdict to decouple event producers from consumers.
from collections import defaultdict
from dataclasses import dataclass, field
from typing import Callable, Dict, List, Set
@dataclass
class EventBus:
_subscribers: Dict[str, List[Callable]] = field(
default_factory=lambda: defaultdict(list)
)
def subscribe(self, event_type: str, handler: Callable…How to Implement the Prototype Pattern with Deep Copy in Python
Implements the Prototype design pattern using copy.deepcopy to clone complex objects without sharing mutable state.
import copy
from dataclasses import dataclass, field
from typing import List
@dataclass
class Engine:
horsepower: int
@dataclass
class Car:
brand: str
engine: Engine
accessories: List[str] = field(default_factory=list)
def clone_prototype(car: Car) -> Car:
return copy.deepcopy(car)
if __name__ …How to Implement the Repository Pattern in Python with an In-Memory Dict
Stores, retrieves, updates, and deletes user records in memory using a Repository abstraction over a plain dict, isolating data access from business logic.
class UserRepository:
def __init__(self):
self._storage = {}
self._next_id = 1
def create(self, name, email):
user_id = self._next_id
self._next_id += 1
self._storage[user_id] = {"id": user_id, "name": name, "email": email}
return self._storage[user_id]
def…How to Build a Simple Filter Helper in Python for API Design
Create a reusable data filter service with dataclasses that mimics gRPC request/response patterns for filtering dataset records.
from dataclasses import dataclass, field
from typing import List, Optional, Dict, Any
@dataclass
class FilterRequest:
"""A simple filter request mirroring a gRPC message structure."""
field_name: str
operator: str # eq, ne, gt, lt, contains
value: Any
page_size: int = 10
page_token: Optional…How to Build a Microservice Helper in Python
A beginner-friendly Python helper that validates input, normalizes service responses, and simulates user management—showing clean patterns for microservice development.
import json
from typing import Any, Dict, List
class DataValidator:
"""Simple validator for common data patterns."""
@staticmethod
def is_valid_email(value: str) -> bool:
"""Check if value looks like an email."""
return "@" in value and "." in value.split("@")[-1]
@staticmethod
…How to Demonstrate the Shared Database Antipattern in Python
This code simulates a shared database where multiple services write and read the same SQLite table, illustrating tight coupling and its pitfalls.
import sqlite3
from pathlib import Path
def create_shared_db(db_path: Path) -> None:
"""Mock demonstrating the shared database antipattern where multiple
services access the same database, causing tight coupling."""
conn = sqlite3.connect(db_path)
cur = conn.cursor()
cur.execute("""
CREATE…How to Use the Adapter Pattern to Mock a Legacy System in Python
This code demonstrates the Adapter pattern, allowing a modern interface to interact with a legacy system by wrapping its outdated method.
class LegacySystem:
def legacy_method(self, data):
return f"Legacy processed: {data}"
class ModernInterface:
def process(self, data):
raise NotImplementedError
class Adapter(ModernInterface):
def __init__(self, legacy):
self.legacy = legacy
def process(self, data):
re…How to Mock a File Source Watch Directory in Python
Poll a directory for new files and log changes, simulating a watch directory for data ingestion patterns.
import os
import time
from pathlib import Path
def watch_directory(dir_path: str, poll_interval: float = 1.0, max_iterations: int = 5):
"""
Mock a file-source watch directory by polling for changes.
Returns new files detected during each poll cycle.
"""
directory = Path(dir_path)
directory.mk…Browse by section
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