Skip to content

Shell completion

duho generates static completion scripts for bash, zsh, fish, and PowerShell. Static means the script is a plain shell function you install once — there's no runtime dependency and, unlike argcomplete, your program is not re-invoked on every keypress.

Adding the flag

Set _completion_ = True to add a --print-completion {bash,zsh,fish,powershell} option:

import duho

class App(duho.Args):
    """My tool."""

    _completion_ = True
    _subcommands_ = [Serve, Build]

# bash
app --print-completion bash > ~/.local/share/bash-completion/completions/app

# zsh (somewhere on your $fpath)
app --print-completion zsh > ~/.zfunc/_app

# fish
app --print-completion fish > ~/.config/fish/completions/app.fish

# PowerShell — emit and evaluate (add to your $PROFILE to persist)
app --print-completion powershell | Out-String | Invoke-Expression

The PowerShell emitter registers a Register-ArgumentCompleter -Native script block that resolves the current subcommand path to its flags, subcommand names, and choice values; a command taking a free/path value offers nothing, so PowerShell's own file completion takes over.

_completion_ is off by default — the same opt-in precedent as _version_ — so the flag doesn't clutter --help for tools that don't want it.

Without the flag

Generate a script without exposing the option at all:

import sys
import duho

duho.print_completion(App, "bash", file=sys.stdout)

What gets completed

The generator walks the built parser tree, so it knows everything duho knows:

  • Subcommands, including nested _subcommands_ trees.
  • Option flags for the command and for whichever subcommand is being typed.
  • Choices — a Literal or enum.Enum field offers its values as completion candidates.
  • Paths — a pathlib.Path-typed field gets the shell's native file and directory completion.

Regenerating

The script is a snapshot of your CLI's shape. Regenerate it when you add or rename commands or options — typically as a release step, or from a make target, so the shipped completions never drift from the actual interface.