Code Explainers
Intermediate code explainers
php
<?php declare(strict_types=1);
Counting business days in PHP
dates
immutability
hash-lookup
Intermediate
7 steps
java
@Configuration public class PaymentGatewayClientConfig { @Bean
Building a resilient RestClient in Spring
retry
http-client
backoff
Intermediate
9 steps
go
package handlers import ( "net/http"
Custom struct-level validation in Gin
validation
struct-tags
cross-field
Intermediate
7 steps
python
from django.db import models from django.db.models import F, Sum, DecimalField from django.db.models.functions import Coalesce
Recomputing order totals in Django
annotations
aggregation
custom-manager
Intermediate
9 steps
rust
use axum::{ body::Body, extract::Request, http::{header::SET_COOKIE, HeaderValue},
Flash messages via Axum middleware
middleware
shared-state
cookies
Intermediate
8 steps
typescript
type ToastVariant = "info" | "success" | "warning" | "error"; interface Toast { id: string;
A self-dismissing toast store with dedup
observer-pattern
deduplication
timers
Intermediate
10 steps
php
<?php namespace App\Services;
A cached settings service in Laravel
caching
memoization
cache-invalidation
Intermediate
8 steps
go
package config import ( "os"
Layered config resolution in Go
configuration
closures
higher-order-functions
Intermediate
8 steps
rust
use std::collections::HashSet; use std::fs; use std::path::{Path, PathBuf}; use std::thread;
Polling a directory for new files in Rust
polling
filesystem
callbacks
Intermediate
6 steps
ruby
require "erb" class TemplateRenderer class MissingVariableError < StandardError; end
A safe ERB template renderer in Ruby
metaprogramming
method_missing
binding
Intermediate
10 steps
java
public final class RetryExecutor { private final int maxAttempts; private final Duration baseDelay;
Retry with exponential backoff in Java
retry
exponential-backoff
jitter
Intermediate
7 steps
ruby
class ReverseGeocodeSignupJob < ApplicationJob queue_as :default retry_on Geocoder::OverQueryLimitError, wait: 5.minutes, attempts: 3
How Rails jobs handle reverse geocoding
background-jobs
error-handling
geocoding
Intermediate
7 steps
java
@Service public class ProductLookupService { private final ProductRepository productRepository;
How Spring caching layers a product lookup
caching
cache-eviction
fallback
Intermediate
8 steps
javascript
import type { MetadataRoute } from 'next' import { db } from '@/lib/db' const URLS_PER_SITEMAP = 50_000
Sharding a large sitemap in Next.js
sitemap
pagination
seo
Intermediate
6 steps
typescript
type RGB = readonly [number, number, number]; interface ColorStop { offset: number;
Interpolating a color gradient in TypeScript
interpolation
data-visualization
color
Intermediate
8 steps
php
final class FormEditorHistory { private SplStack $undoStack; private SplStack $redoStack;
Undo/redo with two stacks in PHP
undo-redo
stack
state-management
Intermediate
9 steps
go
package api import ( "encoding/json"
Safely decoding JSON in a Go HTTP handler
http
json-decoding
input-validation
Intermediate
8 steps
php
<?php namespace App\Reports;
Bucketing spending by time period in Laravel
aggregation
date-bucketing
collections
Intermediate
9 steps