Code Explainers

Code explainers tagged #decorators

typescript 
import { NestFactory } from '@nestjs/core';
import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger';
import { ValidationPipe } from '@nestjs/common';
import { ApiProperty } from '@nestjs/swagger';

Wiring validation and Swagger docs in NestJS

validation openapi decorators
Intermediate 8 steps
python 
from functools import wraps
import asyncio
 
from fastapi import APIRouter, FastAPI, Request

Per-route request timeouts in FastAPI

decorators async timeouts
Intermediate 6 steps
typescript 
import {
  CanActivate,
  ExecutionContext,
  Injectable,

Role-based access with a NestJS guard

authorization guards decorators
Intermediate 6 steps
typescript 
import { Exclude, Expose, Transform, Type } from 'class-transformer';
 
export class AddressEntity {
  street: string;

Shaping API responses with class-transformer in NestJS

serialization decorators dto
Intermediate 10 steps
typescript 
type AsyncMethod = (...args: any[]) => Promise<any>;
 
function LogExecutionTime(thresholdMs = 0) {
  return function <T extends AsyncMethod>(

A method decorator that times async calls

decorators higher-order-functions async
Advanced 9 steps
typescript 
import { Controller, Get, Param, Query, Redirect, NotFoundException } from '@nestjs/common';
import { LinksService } from './links.service';
 
@Controller('links')

Handling HTTP redirects in NestJS

redirects routing decorators
Intermediate 7 steps
python 
import threading
from functools import wraps
 
 

A thread-safe debounce decorator in Python

decorators debounce threading
Advanced 6 steps
python 
import time
import threading
from enum import Enum
from functools import wraps

Building a circuit breaker in Python

circuit-breaker resilience decorators
Advanced 7 steps
python 
from functools import wraps
 
import jwt
from flask import current_app, g, jsonify, request

How a JWT auth decorator works in Flask

decorators authentication jwt
Intermediate 6 steps
python 
import click
 
 
@click.command()

Building a typed CLI with Click

cli decorators validation
Intermediate 7 steps
python 
from functools import wraps
from flask import Blueprint, session, request, redirect, url_for, flash, render_template
from werkzeug.security import check_password_hash
 

Session-based auth with a Flask Blueprint

authentication decorators sessions
Intermediate 9 steps
python 
from functools import wraps
 
from django.core.cache import cache
from django.http import JsonResponse

Building a rate-limit decorator in Django

decorators rate limiting caching
Intermediate 7 steps
python 
from functools import lru_cache
import math
 
 

Memoizing number theory with lru_cache

memoization number-theory caching
Intermediate 8 steps
typescript 
import {
  createParamDecorator,
  ExecutionContext,
  UnauthorizedException,

Building a @CurrentUser decorator in NestJS

decorators authentication request-context
Intermediate 6 steps
typescript 
import {
  CanActivate,
  ExecutionContext,
  Injectable,

Role-based route guards in NestJS

authorization decorators metadata-reflection
Intermediate 8 steps
typescript 
import {
  CanActivate,
  ExecutionContext,
  Injectable,

A rate-limiting guard in NestJS

rate-limiting guards metadata
Intermediate 7 steps
python 
import random
import time
import logging
from functools import wraps

A retry decorator with exponential backoff

decorators retry exponential-backoff
Intermediate 6 steps
python 
from functools import wraps
 
 
def memoize(func):

Building a memoize decorator in Python

decorators closures memoization
Intermediate 5 steps