protocli

Signature-driven CLI dispatcher: typed function signatures become argparse parsers, modules become lazily-imported subcommands, with nested dispatch, --help-all and shell completions.

# mytool/__main__.py
from protocli import Dispatcher

Dispatcher(
    "mytool",
    {
        "greet": greet,          # a callable: its signature IS the parser
        "db": "mytool.db",       # a module path: lazy-imported on dispatch
    },
).run()

A callable (or a module's main) maps to CLI arguments by signature:

def greet(
    name: str,                        # required positional
    title: str | None = None,         # optional positional
    *rest: str,                       # variadic
    loud: bool = False,               # --loud   (keyword-only, default False)
    times: int = 1,                   # --times N
    lang: Literal["en", "hu"] = "en", # --lang restricted to choices
    tags: list[str] = [],             # --tags a,b,c  (comma-separated)
): ...

A module can instead expose its own nested _dispatcher = Dispatcher(...), or a get_completions(rest) hook for custom shell completion (return [FILE_COMPLETION] to request native pathname completion).

mytool --help-all prints every parser in the tree; mytool --complete <args…> emits completion candidates for shell integration.

Auto-discovery over a package's public modules:

Dispatcher.from_package("mytool").run()