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
filepath.Walk — Recursive Tree Walk
`filepath.WalkDir` (Go 1.16+) is the modern, faster version. Visit every file/dir under a root; the callback decides whether to skip or process.
@admin
Go
select — Multiplex Channel Operations
`select` is like a switch for channels — runs whichever case is ready. Use `default` for non-blocking sends/receives; `case <-time.After(d)` for timeouts.
Bash
Generate UUID
Several portable ways to mint a v4 UUID from the shell — useful for request IDs, idempotency keys, temporary filenames.
Bash
Background Jobs + wait
Run several commands in parallel with `&`, then wait for all of them with `wait`. Collect exit codes via $! and check after wait returns.
HTML
HTML5 Document Boilerplate
Sensible HTML5 starting template: UTF-8 charset, responsive viewport, language attribute, semantic landmarks. Drop this in every new project before adding anything else.
Rust
From / Into Conversions
Implement `From` and you get `Into` for free. Then `.into()` and `T::from(x)` both work. The single most idiomatic way to express type conversions in Rust.
Kotlin
Jetpack Compose — Basic Composable
Compose is Android's modern declarative UI toolkit. A `@Composable` function describes UI; the runtime re-runs it when inputs change. Replaces XML layouts entirely.
Go
iota — Auto-Incrementing Constants (Enums)
Go has no `enum` keyword but `iota` inside a const block gives you the same effect. Each line is the previous expression with iota auto-incremented.
Go
Type Switches
When you have an `interface{}` (or any) and need to dispatch on its underlying type, use `switch v := x.(type)`. Cleaner than a chain of type-assertions.
Bash
Filter Lines by Regex
grep -E (extended regex) is the right tool 95% of the time. Combine -i (case-insensitive), -v (invert), -n (line numbers), -B/-A (context lines).
Bash
Count Occurrences of a Pattern
Several ways to count matches: lines containing X, total matches across a file, matches grouped by capture, etc.
Bash
Check Command Exists Before Using It
`command -v` is the portable, fast way to check whether a binary is on $PATH. Avoid `which` (its behavior varies between systems).
Bash
Recursive Directory Walker with Predicate
Use `find -print0` + `read -d ""` to safely iterate filenames that may contain spaces, newlines, or quotes. Standard bash for-loop over `find` output breaks on these.
Kotlin
async / await for Parallel Results
`async` returns a `Deferred<T>` — like a Future. Use it when you need a RESULT back, in parallel. Call `.await()` to get the value (suspends until ready).
SQL
LATERAL Join — Per-Row Subquery
PostgreSQL `LATERAL` lets a join's right-hand side reference the left-hand row — like a correlated subquery, but supplying multiple columns or rows. Perfect for "top-N per group".
Go
Signal Handling with signal.NotifyContext
Go 1.16+ `signal.NotifyContext` returns a context that's canceled on the listed signals. Cleaner than the legacy `signal.Notify(channel)` dance for graceful shutdown.
PHP
Recursive Directory Walker
Yield every file under a directory using a generator and SPL's RecursiveIteratorIterator. Filter by extension or any other predicate without slurping all paths into memory first.