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Build a Case-Insensitive Dict with a Wrapper Class in Python
Create a custom dict subclass that treats keys as case-insensitive by normalizing them to lowercase, with a full set of common dict methods.
class CaseInsensitiveDict:
def __init__(self, data=None):
self._data = {}
if data:
self.update(data)
def __setitem__(self, key, value):
self._data[str(key).lower()] = value
def __getitem__(self, key):
return self._data[str(key).lower()]
def __delitem__(sel…How to Test Properties with Random Inputs in Python
Write a simple property-based test in Python using random string generation to verify that string invariants like reverse-twice identity and uppercase idempotence always hold.
import random
import string
def generate_random_string(length: int) -> str:
"""Generate a random alphanumeric string of given length."""
chars = string.ascii_letters + string.digits
return "".join(random.choice(chars) for _ in range(length))
def reverse_twice_is_identity(s: str) -> bool:
"""Propert…How to Apply the Clean Architecture Dependency Rule in Python
Demonstrates the dependency rule with a Protocol repository, a use case, and a presenter wired together at a composition root.
from dataclasses import dataclass
from typing import List, Protocol
class Repository(Protocol):
def get_items(self) -> List[str]:
...
@dataclass
class InMemoryRepository:
items: List[str]
def get_items(self) -> List[str]:
return self.items
class UseCase:
"""Application layer depends…How to Build a Pipe and Filter Text Processing Chain in Python
A functional pipe-and-filter chain that transforms text through uppercase, whitespace normalization, number removal, stopword filtering, and file export.
import re
import sys
def pipe_filter_chain(stream):
def uppercase(text):
return text.upper()
def strip_whitespace(text):
return " ".join(text.split())
def remove_numbers(text):
return re.sub(r"\d+", "", text)
def remove_stopwords(text, stopwords={"the", "and", "of", "in"}):…How to Mock Service Call Timeouts in Python
Simulate service calls with configurable timeouts using Mock to patch sleep and randomness, covering success and timeout cases.
import time
from unittest.mock import Mock, patch
# Simulate a service call with configurable timeout
def call_service(service_name, timeout=5):
"""Mock a service call that may time out."""
start = time.time()
print(f"Calling {service_name}...")
# Simulate service latency (randomized for realism)…Browse by section
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Guide: free Python code samples library
Copy-ready Python snippets for learners and developers
PythonSkillset code samples are short, focused examples organised by topic and difficulty. Every snippet is server-rendered HTML — readable by search engines and easy to copy. Open any sample, read the notes, copy the code, then press Try in editor to run it in the browser with Pyodide.
How to use this library
- Pick a topic section — strings, lists, files, functions, and more
- Open a sample, read How it works, and copy the code block
- Run it in the IDE, tweak values, then take a related quiz or tutorial lesson
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.