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
Python
Stream Large CSV with DictReader
Iterate over a CSV row-by-row as a dict — never loading the whole file. Tolerant of UTF-8 BOMs (utf-8-sig). Generator wrapper makes consumers naturally use for/break.
@admin
SQL
CASE WHEN — Conditional Values
Inline if/else inside a SELECT, ORDER BY, or aggregation. The Swiss-army knife for converting raw column values into labels or buckets.
Kotlin
reified Type Parameters
In an `inline` function, a `reified` type parameter survives erasure — you can use `T::class`, `is T`, `as T` at runtime. The killer use-case for JSON parsers ("give me a List<User>").
Rust
Generic Function with Trait Bounds
Use `T: Trait` to require a capability on a generic parameter. The `where` clause is the more readable variant when bounds get long.
SQL
UPSERT — MySQL ON DUPLICATE KEY UPDATE
MySQL's flavor of upsert. Triggers when an INSERT would violate a PRIMARY KEY or UNIQUE constraint. Use `VALUES()` (or `NEW.col` in MySQL 8.0.20+) to reference the would-be-inserted row.
Bash
ANSI Color Output Helpers
Wrap printf with ANSI escape codes for color and bold. Auto-disable if stdout isn't a TTY (so piping to a file doesn't pollute it with escape sequences).
Go
sync.Pool — Reuse Allocations
`sync.Pool` keeps a pool of reusable objects to reduce allocator pressure in hot paths. Good for byte buffers, JSON encoders, or anything you allocate frequently and only need briefly.
Go
json.RawMessage — Deferred Decoding
`json.RawMessage` is a `[]byte` that survives a decode pass. Use it for envelope-style JSON where one field's type depends on another (e.g. `{"type":"X","payload":{...}}`).
Java
JUnit 5 — Basic Test
JUnit 5 is the modern standard. `@Test` marks a method as a test; `Assertions.*` provides the assertion API. `@BeforeEach` runs setup before every test.
HTML
Iframe with Sandbox + lazy loading
Embed third-party content (YouTube, Stripe, maps) safely. `sandbox` restricts what the embedded page can do. `loading="lazy"` defers offscreen iframes — huge perf win for blog posts with multiple embeds.
Java
Semaphore — Bounded Concurrency
Limit how many threads can enter a critical section. `acquire()` blocks until a permit is available; `release()` returns one. Use for rate limits, connection pools, or any "max N at a time" pattern.
Kotlin
kotlin.time — Duration and measureTime
`kotlin.time.Duration` is a typesafe time amount with friendly literal syntax (`5.seconds`, `2.minutes`). `measureTime { }` benchmarks a block.
Go
Worker Pool with Channels
Spawn N worker goroutines, feed them tasks over a jobs channel, collect results on a results channel. Idiomatic Go pattern for bounded concurrency.
Rust
anyhow for Application Errors
`anyhow::Result<T>` is `Result<T, anyhow::Error>` — a type-erased error that captures any other error AND adds context via `.context()`. The app-author's pick (use thiserror for libraries).
Python
Slugify (unicodedata, zero deps)
Convert any string to a URL-safe slug using only stdlib. Normalizes Unicode (NFKD), strips combining marks, lowercases, replaces non-alphanumerics with a separator.
Kotlin
zip and zipWithIndex
`zip` pairs elements positionally; the result is the length of the shorter list. `withIndex()` gives you `(index, value)` pairs without the manual `forEachIndexed`.
PHP
Resize Image to Max Dimension
Shrink an uploaded image so its longest side is no more than $maxDim pixels, preserving aspect ratio. Re-encodes to JPEG at the given quality. Uses the GD extension.