Tags
#php
#kotlin
#bash
#go
#sql
#rust
#typescript
#html
#java
#python
#files
#utils
#strings
#http
#concurrency
#async
#json
#arrays
#security
#types
#crypto
#database
#dates
#format
Go
database/sql — Open + Query
`database/sql` is driver-agnostic — pick a driver (`pgx/stdlib`, `go-sql-driver/mysql`, `mattn/sqlite3`). Always `defer db.Close()` only on app exit; the pool is meant to be long-lived.
@admin
Java
Generic Method + Bounded Type Parameters
A method can have its own type parameter independent of the class. `<T extends Comparable<T>>` constrains T to types that can be compared.
PHP
Build & Sign a JWT (HS256)
Generate a JWT manually using only base64-url and hash_hmac — no library required. Demonstrates header/payload/signature concatenation and the exp claim.
Python
Word-Safe Truncate
Cap a string at `max_len` chars without splitting a word; append an ellipsis when truncated. Backs off to the last space if cutting mid-word would happen.
PHP
Validate IP Address (v4 + v6)
Distinguish IPv4 from IPv6, optionally reject private/reserved/loopback ranges. Useful for hardening server-side fetchers against SSRF.
Rust
axum — Hello World HTTP Server
axum is the tokio-team's web framework — composable, type-safe handlers built on tower middleware. The hello-world is small enough to read in one screen.
PHP
Date Range Iterator
Yield each date in a [start, end] interval as a DateTimeImmutable, with a configurable step. Builds on DatePeriod under the hood — but exposes a generator so you can break out early.
PHP
Rotating Log Writer
Append to a single log file but auto-rotate to .1/.2/.3 once the file exceeds a configurable size. No external dependencies — just rename + size check.
Python
asyncio.wait_for — Timeout Wrapper
Cancel a coroutine if it takes longer than `timeout` seconds. Raises asyncio.TimeoutError when fired so the caller can fall back. Python 3.11+ has asyncio.timeout() as a context-manager alternative.
TypeScript
Sum / Mean / Median (numeric arrays)
The descriptive-stat trio for number[]. Median sorts a copy so the input is left alone. Empty input returns 0 / 0 / 0 rather than NaN — opinionated, but predictable.
SQL
Recursive CTE — Walk a Hierarchy
`WITH RECURSIVE` lets a CTE refer to itself. The standard way to walk parent/child trees (org charts, comment threads, category nestings) in a single query.
Python
Dataclass with frozen + slots + defaults
Modern dataclass essentials: immutable instances (frozen=True), tighter memory + faster attribute access (slots=True), and default_factory for mutable defaults so every instance gets its own list.
JavaScript
Unique Array Values
Returns a new array with duplicate values removed. The fast version uses a Set for primitives. The deep version supports deduplicating objects by a specific key, making it suitable for deduplicating API results or merged data sets.
Bash
Generate SSH Keypair Non-Interactively
ssh-keygen normally prompts. Pass -N "" for empty passphrase, -f for the path, -t ed25519 for modern key type. Idempotent — skip if a key already exists.
Kotlin
Ktor Client — POST JSON with Serialization
Combine Ktor + kotlinx.serialization: register the JSON plugin, declare `@Serializable` data classes, the client (de)serializes automatically.
Bash
URL-Encode and URL-Decode
Encode and decode URL-safe strings entirely in bash — no python or external tool required. Useful in pure-shell deployment scripts that need to build query strings.
PHP
Parse Link Header for Pagination
Parse the standard HTTP Link header (RFC 5988) into a relation → URL map. Lets you follow rel="next" pagination in APIs like GitHub without manually building URLs.