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#php
#kotlin
#bash
#go
#sql
#rust
#typescript
#html
#java
#python
#files
#utils
#strings
#http
#concurrency
#async
#json
#arrays
#security
#types
#crypto
#database
#dates
#format
TypeScript
Generic Constraints with `extends`
Generics start unbounded — you can't access any properties of `T`. `T extends { … }` adds a constraint so the body can safely use known shape, while callers can still pass in narrower types.
@admin
Bash
Read Single Keystroke Without Enter
For menus and confirm prompts where you want one-key response (no need to press Enter). -n 1 reads exactly one character, -s silences the echo.
Python
ThreadPoolExecutor for I/O-Bound Work
Parallelize I/O-bound tasks (HTTP requests, file reads, DB queries) without writing thread management code. The default thread count is min(32, os.cpu_count() + 4) — usually the right call.
JavaScript
Calculate Reading Time
Estimates the reading time of a block of text based on an average adult reading speed (default 200 words per minute). Strips HTML tags before counting to handle rich-text content. Returns the result in minutes, rounded up, so a short article always shows at least "1 min read".
Go
UUID Generation (google/uuid)
`github.com/google/uuid` is the standard UUID library. v4 (random) for IDs, v7 (time-ordered) when you want UUIDs that sort chronologically and play nicely with B-tree indexes.
Go
Error Wrapping with %w
`fmt.Errorf` with `%w` wraps an inner error inside an outer one, preserving the chain. Callers can use `errors.Is` / `errors.As` to inspect any level of the chain.
Rust
match with Guards, Ranges, and Bindings
`match` arms can have `if` guards, range patterns (`1..=5`), bindings (`x @ pattern`), and ORs (`A | B`). Combine them for very expressive dispatch.
SQL
INSERT … SELECT — Bulk Copy
Copy/transform rows from a SELECT into another table — the cheapest way to move data within the database. Skip column lists at your peril; positional matching is fragile.
Python
Retry Decorator with Exponential Backoff
Generic retry decorator: attempts × base delay, exponential ramp, random jitter. Filter retryable exceptions via the `on` tuple so logical errors aren't retried.
PHP
Compound Interest Calculator
Compute the future value of an investment compounded n times per year for t years. Returns both the final value and the interest earned.
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.
Go
Sentinel Errors (var ErrFoo = errors.New)
Sentinel errors are package-level singletons you can compare against with `errors.Is`. Use sparingly — they're part of your package's API surface and changing them is a breaking change.
PHP
Smart Title Case
Convert a string to title case while keeping common short words (a, an, the, of, etc.) lowercase — unless they appear at the start or end of the title.
Go
Static File Server
`http.FileServer` serves a directory; combine with `http.StripPrefix` to mount it at a URL path. One line for the most common static-asset use case.
Go
JSON Marshal / Unmarshal
`encoding/json` is the standard library JSON parser. `Marshal` produces compact JSON; `MarshalIndent` produces pretty-printed. `Unmarshal` decodes into a typed value (struct, map, or any).
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.
TypeScript
Retry with Exponential Backoff + Jitter
Retry an async operation up to N times, doubling the delay each attempt with random jitter to avoid thundering herd. Decide retryability via an optional predicate so 4xx errors stop immediately.