boop | Object-oriented programming for bash 4.3+ — real classes, objects, inheritance, and a standard library, in pure bash.

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The framework file is called boop because fun is a feature — but it is not a toy. boop brings real object-oriented programming to bash 4.3+: real classes, real objects, single inheritance with mixins, a namespace system, and a growing standard library. All in pure bash, with no third-party tools and no subshells in the dispatch path.

Why boop

Bash is a glue language. It excels at wiring programs together, not at organizing large amounts of logic. Past a few hundred lines, the usual tools — functions, global variables, naming conventions — start to fight each other: prefixed globals, parallel arrays, subshells spawned just to return a value, state leaking everywhere.

boop gives bash the vocabulary it’s missing: objects with conventionally private state, classes with constructors and inherited methods, a return system that avoids subshells, and a namespace-aware loader that scales from a single script to a library of dozens of classes.

It is not a toy. The framework is ~2,500 lines of bash; the bundled classes are well-tested implementations; the suite runs 1,300+ tests across unit, integration, and property-based cases.

A taste

. boop Cube

into=c Cube size=5 unit=cm
into=vol $c.volume          # 125

$c.toString pretty
# Cube(_a1b2c3) {
#   size   = 5
#   unit   = cm
#   length = 5
#   width  = 5
#   height = 5
# }

Define your own class in a few lines:

. boop

Greeter.greet() {
  local _Class="${_Class:-Greeter}"
  local _Self="${_Self:-${_Class}}"
  local __Greeter_greet_name="I'm a Boop Class"
  [[ "$_Self" == "$_Class" ]] || into=__Greeter_greet_name $_Self.name
  boop.pass "Hello, ${__Greeter_greet_name:-World}!" ${into:-}
}

boopClass Greeter 'has:name public:greet'

into=g Greeter name="from Boop"
into=msg $g.greet
printf '%s\n' "$msg"          # Hello, from Boop!

What you get

Real objects and classes — constructors, properties, single inheritance, and mixins for shared behavior.
A subshell-free return system — into=var $obj.method writes results straight into the caller’s variable via namerefs. No $() fork, no global clobbering.
A namespace-aware loader — . boop List Map Config pulls in classes and their dependencies; :: and / are interchangeable; short names resolve when unambiguous.
A standard library — Collections (List, Map, Set, Stack, Queue, Map.Fast), arbitrary-precision Math, Config, Args, Data.JSON, DateTime, Text.String, SemVer, and more.
CLI tools built on the framework — lens (stream inspection), boson (jq-style JSON query), probe (plaintext HTTP), collider (single-file bundler).
errexit-safe by default — all framework code survives set -e.

Quick start

git clone https://github.com/ydbxmhc/bashClass boop
PATH+=":$PWD/boop"      # so `. boop` works anywhere

No build step. No package manager. Source the framework and start:

. boop List

into=fruits List
$fruits.push apple banana cherry
into=n $fruits.length         # 3
into=v $fruits.get -1         # cherry

Requirements: bash 4.3+ (associative arrays and namerefs); 5.0+ recommended. macOS ships bash 3.2 — brew install bash fixes that.

NUL bytes: bash variables cannot hold or detect NUL bytes; any value containing one is silently truncated at the first. This is a bash limitation that applies throughout the framework. See GOTCHAS.

Documentation

Document	Contents
boop	Full framework reference — return system, dispatch mechanics, naming rules, gotchas
comparison	boop idioms next to Python, Ruby, and Go equivalents
List · Map · Container	Collection API references
Math	Arbitrary-precision arithmetic internals
String	Text.String API — mutators, `-ed` forms, pipelines
DateTime	DateTime API — formatting, arithmetic, DST notes
JSON	Data.JSON parser/serializer
SemVer	Version constraints and the `require:` guard
tools	CLI tools overview — `lens`, `boson`, `probe`, `collider`
TODO	Roadmap and open design questions

boop — fun is a feature.