Every article tagged Python, in one place.
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FastAPI is a Python web framework built on type hints. You describe your inputs and outputs with types, and FastAPI validates requests, serialises responses and generates interactive API docs for you. Install and run pip install "fastapi[standard]" fastapi dev...
Python 3.14 was released in October 2025. Here are the changes most developers will notice. Template strings (t-strings) A t-string looks like an f-string but produces a Template object instead of a finished string. Libraries can then process the interpolated...
Tool use (also called function calling) lets a model request that your code run a function. The model never runs code itself; it returns a structured request and waits for your result. 1. Describe the tools tools = [ { "name": "search_products", "description":...
uv is a Python package and project manager written in Rust. It replaces pip, pip-tools, virtualenv, pyenv and pipx with one tool, and it's dramatically faster. Install curl -LsSf https://astral.sh/uv/install.sh | sh # or: pipx install uv, brew install uv Start...
The official Python SDK includes FastMCP , a high-level API where type hints and docstrings become the tool schema. A working server takes only a few lines. 1. Create the project uv init notes-mcp && cd notes-mcp uv add "mcp[cli]" 2. Write the server # server....
FastAPI's Depends lets endpoints declare what they need (a database session, the current user, pagination settings) and FastAPI provides it. Dependencies can depend on other dependencies, and they're easy to replace in tests. A simple dependency from typing im...
Type hints don't change how Python runs, but editors and type checkers use them to catch bugs and power autocomplete. Modern Python syntax makes them short and readable. The basics def greet(name: str, times: int = 1) -> str: return ", ".join([f"Hello {name}"]...
Both give you classes with typed fields and less boilerplate. The key difference: dataclasses store data, Pydantic validates and converts it. Dataclasses from dataclasses import dataclass, field @dataclass(frozen=True, slots=True) class Money: amount: int # pa...
asyncio lets one thread wait on many network operations at once. It shines for I/O-heavy work: calling APIs, scraping, chat servers, database queries. The basics import asyncio import httpx async def fetch_status(client: httpx.AsyncClient, url: str) -> int: re...
match looks like a switch statement, but it's more powerful: it can check the shape of data and pull values out of it in one step. Literals and alternatives def http_message(status: int) -> str: match status: case 200 | 201: return "OK" case 404: return "Not f...
Two common needs in API servers: running code once when the app starts or stops, and doing a bit of work after the response is sent. Lifespan: startup and shutdown from contextlib import asynccontextmanager import httpx from fastapi import FastAPI @asynccontex...
pytest is the standard testing tool for Python. Tests are plain functions using plain assert , and pytest's output shows exactly what differed. First tests # test_pricing.py import pytest from pricing import apply_discount def test_ten_percent_discount(): asse...
Ruff is a Python linter and formatter written in Rust. It implements rules from Flake8 and many of its plugins, sorts imports like isort, and formats code in a Black-compatible style, typically in a fraction of a second. Install and run uv add --dev ruff uv ru...
A list holds every item in memory. A generator produces items one at a time, on demand. For large files, streams or infinite sequences, that's the difference between working and running out of memory. yield def read_lines(path): with open(path) as f: for line...
A single main.py is perfect for a prototype. As the API grows, split it by feature so each area of the product lives together. A feature-based layout app/ main.py # creates the app, includes routers config.py # settings from environment db.py # engine, session...
For decades, CPython's Global Interpreter Lock (GIL) allowed only one thread to run Python bytecode at a time. Threads helped with I/O, but not with CPU-heavy work. Free-threaded builds of Python remove the GIL. The timeline Python 3.13 introduced an experimen...
