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
Kotlin
apply — Configure Object, Return Itself
`x.apply { ... }` runs the block with `x` as `this` (so you call methods/set properties directly) and returns `x`. The canonical builder-style configuration.
@admin
Python
AES-GCM Encrypt / Decrypt (cryptography)
Authenticated symmetric encryption using AES-256-GCM from the `cryptography` package. Stores nonce + ciphertext + tag together as base64 so storage is a single column.
TypeScript
Promise.allSettled — Typed Results
`Promise.all` rejects on the first failure; `allSettled` waits for every promise and gives you per-promise status. Pair with a type guard to split fulfilled from rejected.
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.
Kotlin
inline Functions — Zero-Cost Lambdas
`inline fun` copies the body (including lambda bodies) into the call site at compile time. Result: no `Function` object allocated for the lambda; `return` from inside the lambda exits the enclosing function.
Kotlin
Generic Class and Function
`<T>` declares a type parameter. Use it on classes (`Box<T>`) and functions (`fun <T> identity(x: T) = x`). Type bounds (`T : Comparable<T>`) constrain what T can be.
Bash
Tail Last N Lines (no `tail` shortcuts)
`tail -n 20` works for any case where tail is available. The pure-bash version below is useful inside containers or rescue shells where coreutils is missing.
Java
Singleton via enum
`enum` with a single value is the simplest correct singleton implementation: lazy, thread-safe, serialization-safe, reflection-safe. Joshua Bloch's recommendation in Effective Java.
Java
flatMap — Flatten Nested Streams
Map each element to a Stream, then concatenate all of them into one. Used everywhere from "all words from a list of sentences" to "all permissions from a list of roles".
SQL
SELECT DISTINCT and Counting Uniques
`DISTINCT` removes duplicate rows. Combine with `COUNT(DISTINCT col)` to count uniques in aggregations — different from `COUNT(*)`.
PHP
Recursive Deep Merge
Merge two associative arrays at any nesting depth — like array_merge_recursive, but later values OVERWRITE earlier ones at the leaf level instead of combining them into arrays. Perfect for config-file overrides.
PHP
Sort by Multiple Keys
Stable multi-column sort for arrays of associative rows. Each column can be sorted ASC or DESC independently. Wraps usort with a chained comparator.
Java
ExecutorService — Thread Pools
`ExecutorService` is the modern way to manage threads. Submit Callables/Runnables, get Futures back. Always shutdown the executor — and prefer try-with-resources on Java 19+ where ExecutorService is AutoCloseable.
JavaScript
IndexedDB Wrapper
A Promise-based wrapper for the IndexedDB API — simplifies the verbose request/onsuccess/onerror pattern into clean async/await calls. Supports get, set, delete, and getAll operations on a named object store. Ideal for storing large client-side datasets, offline data, and blobs that exceed localStorage limits.