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go-ruby-optparse documentation

Ruby's OptionParser argv-parsing engine in pure Go — MRI-compatible, no cgo.

go-ruby-optparse/optparse is a faithful, pure-Go (zero cgo) reimplementation of Ruby's OptionParser, matching reference Ruby (MRI) byte-for-byte. The module path is github.com/go-ruby-optparse/optparse.

It was extracted from rbgo's prelude/internals into a reusable standalone library: the module is standalone and importable by any Go program, and it is the backend bound into go-embedded-ruby by rbgo as a native module — just like go-ruby-regexp and go-ruby-erb. The dependency runs the other way: this library has no dependency on the Ruby runtime.

Status: engine complete — MRI byte-exact

Faithful port of MRI's lib/optparse.rb matching engine: long / short / abbreviated / bundled options, the --[no-]opt form, type coercion, the parse! / order! / permute! / getopts modes, and the full error taxonomy. The per-option callbacks stay in the host. Validated by a differential oracle against the system ruby — residual argv and error classes compared — at 100% coverage, gofmt + go vet clean, CI green across the six 64-bit Go targets and three OSes.

Quick taste

p := optparse.New()
p.On(optparse.Spec{Long: "verbose", Short: "v"})
p.On(optparse.Spec{Long: "level", Arg: optparse.Required, Type: optparse.Int})

m, rest, err := p.ParseBang([]string{"-v", "--lev=3", "file"})
// m matches -v and the abbreviated --level=3 (coerced to int 3)
// rest == []string{"file"}; the host runs each Spec's callback

Repositories

Repo What it is
optparse the library — Ruby's OptionParser in pure Go
docs this documentation site (MkDocs Material, versioned with mike)
go-ruby-optparse.github.io the organization landing page (Hugo)
brand logo and brand assets

Principles

  • Pure Go, CGO_ENABLED=0 — trivial cross-compilation, a single static binary, no C toolchain.
  • MRI byte-exact. Output matches reference Ruby exactly, not approximately, validated by a differential oracle against the ruby binary.
  • Standalone & reusable. Extracted from rbgo's internals; no dependency on the Ruby runtime — the dependency runs the other way.
  • 100% test coverage is the target, enforced as a CI gate, across 6 arches and 3 OSes.

Where to go next

  • Why pure Go — why this slice of Ruby is deterministic enough to live as a standalone, interpreter-independent Go library.
  • Usage & API — the public surface and worked examples.
  • Roadmap — what is done and what is downstream by design.

Source lives at github.com/go-ruby-optparse/optparse.