output¶

Structured, themeable output formatting for CLI tools.

output gives a command-line tool one configured Renderer that speaks both languages a CLI needs at once — human-readable text for a terminal and machine-readable JSON/YAML for a pipeline — plus tables, spinners, progress bars and live status lines. It degrades gracefully to plain output when it is not attached to a terminal.

r := output.New(output.WithWriter(os.Stdout), output.WithFormat(format))

_ = r.Write(result, func(w io.Writer) {
    fmt.Fprintf(w, "%s is up to date (%s)\n", result.Name, result.Version)
})

Highlights¶

• Configure once, render anywhere. The writer, format, theme and interactivity are fixed on the Renderer; every method reads them. No globals — trivially testable with a bytes.Buffer.
• One façade, six formats. Write, Table, Render, Emit/EmitError, Status, Progress and Spin share the same configured destination and format.
• Unicode-correct. Widths and truncation use display width, so CJK, emoji and combining characters never corrupt a table or a status line.
• Framework-free core. Importing output never pulls cobra or pflag; the cobra wiring is the opt-in output/cobra subpackage.

Where next¶

• Tutorial — getting started, then build a CLI that speaks text and JSON end to end.
• How-to guides — emit JSON, render tables, progress & spinners, theming, cobra wiring.
• Reference — formats & options, behaviour by format, errors & failure modes, what this does not do, and the full API on pkg.go.dev.
• Explanation — the Renderer façade, interactive vs plain rendering, framework-free core.

Part of the phpboyscout Go toolkit — small, framework-free Go modules extracted from go-tool-base.

Further reading¶

The blog carries a curated route through this subject: Building a command-line tool in Go collects everything written about it, ordered so you can start at the beginning rather than newest-first.