xclif 0.4.0

Xliner's CLI Framework

Xclif

Xliner's CLI Framework

Read the Manifesto to understand why Xclif exists and how it compares to Click, Typer, and argparse.

Installation

pip install xclif

Or with uv:

uv add xclif

Quick Start

Your directory structure is your command tree:

myapp/
├── __init__.py
├── __main__.py
└── routes/
    ├── __init__.py       →  myapp
    ├── greet.py          →  myapp greet
    └── server/
        ├── __init__.py   →  myapp server
        ├── start.py      →  myapp server start
        └── stop.py       →  myapp server stop

# routes/greet.py
from xclif import command

@command()
def _(name: str, template: str = "Hello, {}!") -> None:
    """Greet someone by name."""
    print(template.format(name))

# __main__.py
from xclif import Cli
from . import routes

cli = Cli.from_routes(routes)
if __name__ == "__main__":
    cli()

No default → positional argument. Has default → --template option. Docstring → help text. Drop a file in the right folder and the command exists.

Features

• File-based routing — directory structure is the command tree
• Decorator + type-hint API — function signatures define the CLI contract
• Rich integration — beautiful help pages, formatted errors, progress indicators
• Built-in logging and verbosity — --verbose / -v wired up automatically
• Config management — WithConfig[T] reads from config files or environment variables (CLI flag > env var > config file > default)
• Agent-optimized help — auto-detects non-TTY output and emits a compact, token-efficient format for LLM agents and scripts
• Autogenerated shell completions — bash, zsh, fish
• Minimal overhead — custom parser built from scratch for fast startup; xclif compile pre-builds a static manifest to eliminate route-walking cost
• Plugin discovery (planned) — third-party subcommands via entry points (like Git or cargo)
• Easy testing — command.execute(["greet", "Alice"]) with explicit arg lists, no mocking needed

Performance

Performance is not a primary focus of Xclif. If startup latency is a hard constraint, Python is probably the wrong tool for the job. These numbers are here for fun. That being said, we do recommend switching to a manifest-based setup for large codebases.

Startup time

Benchmarked on macOS (Apple Silicon, Python 3.12, 30 iterations + 3 warmup, wall-clock subprocess time):

Scenario	Click	Typer	Xclif (from_routes)	Xclif (flat)	Xclif (manifest)
greet World	28.0	39.8	41.0	27.2	26.9 ✅
greet + options	27.9	37.8	40.9	26.3 ✅	26.7
config set	27.6	38.0	40.5	26.1 ✅	26.9
config get	27.9	38.1	40.3	26.2 ✅	26.8
--help	29.2 ✅	82.2	59.6	46.6	47.2
greet --help	29.7 ✅	83.8	59.3	46.8	47.6

Xclif (flat) uses the decorator API (Command.command() / Command.group()) instead of from_routes, and is the fastest framework for command execution — edging out Click by ~1–2 ms. The --help gap (~20 ms vs Click) is Rich's lazy-import cost. If better scaling is desirable for large codebases, the manifest compiler pre-builds a static manifest that matches flat API performance without requiring manual command registration.

Typer is the slowest overall: it wraps Click with extra overhead, and its Rich-based help rendering adds ~52–53 ms on --help scenarios.

from_routes adds ~13–15 ms for the package walker on top of Xclif (flat) — the trade-off for zero-registration file-based routing.

from_manifest eliminates that cost. Running xclif compile myapp.routes once generates a _xclif_manifest.py next to your routes package; loading it with Cli.from_manifest() skips the filesystem walk entirely, matching flat API performance.

# __main__.py — manifest variant
from xclif import Cli
from myapp import _xclif_manifest

cli = Cli.from_manifest(_xclif_manifest)
if __name__ == "__main__":
    cli()

# regenerate after adding or removing routes
xclif compile myapp.routes

To reproduce (requires hyperfine — brew install hyperfine on macOS):

bash benchmarks/bench_frameworks.sh

Parse and dispatch latency

Measured in-process (no subprocess, no import cost) on the same machine, 5 000 iterations:

Scenario	Click	Typer	Xclif
greet World	72 µs	496 µs	2.7 µs ✅
greet + options	77 µs	490 µs	4.0 µs ✅
config set	82 µs	578 µs	3.4 µs ✅
config get	79 µs	553 µs	3.2 µs ✅
--help	131 µs ✅	1 879 µs	483 µs
greet --help	142 µs ✅	2 281 µs	553 µs

Xclif's custom parser is ~25× faster than Click and ~170× faster than Typer for command dispatch. The --help cases are slower than Click because Rich is doing real formatting work; Typer is dramatically slower there due to its reflective help generation.

uv run python benchmarks/bench_parsing.py

Contributing

See CONTRIBUTING.md.

License

This project is licensed under the MIT license.