Typer
Typer, build great CLIs. Easy to code. Based on Python type hints.
Documentation: https://typer-cloup.netlify.app
Source Code: https://github.com/alexreg/typer-cloup
NOTE: This project is a fork of the original Typer project, building upon Cloup rather than Click (of which Cloup is an extension). typer-cloup is largely but not entirely backward compatible with typer 0.4.2, and also includes some changes to typer made since then.
Typer is a library for building CLI applications that users will love using and developers will love creating. Based on Python 3.7+ type hints.
The key features are:
- Intuitive to write: Great editor support. Completion everywhere. Less time debugging. Designed to be easy to use and learn. Less time reading docs.
- Easy to use: It's easy to use for the final users. Automatic help, and automatic completion for all shells.
- Short: Minimize code duplication. Multiple features from each parameter declaration. Fewer bugs.
- Start simple: The simplest example adds only 2 lines of code to your app: 1 import, 1 function call.
- Grow large: Grow in complexity as much as you want, create arbitrarily complex trees of commands and groups of subcommands, with options and arguments.
FastAPI of CLIs¶
Typer is FastAPI's little sibling.
And it's intended to be the FastAPI of CLIs.
Requirements¶
Python 3.7+
Typer stands on the shoulders of a giant. Its only internal dependency is Cloup, which is itself based on Click.
Installation¶
$ pip install typer-cloup
---> 100%
Successfully installed typer-cloup
Example¶
The absolute minimum¶
- Create a file
main.pywith:
import typer_cloup as typer
def main(name: str):
typer.echo(f"Hello {name}")
if __name__ == "__main__":
typer.run(main)
Run it¶
Run your application:
// Run your application
$ python main.py
// You get a nice error, you are missing NAME
Usage: main.py [OPTIONS] NAME
Try "main.py --help" for help.
Error: Missing argument 'NAME'.
// You get a --help for free
$ python main.py --help
Usage: main.py [OPTIONS] NAME
Arguments:
NAME [required]
Options:
--help Show this message and exit.
// When you create a package you get ✨ auto-completion ✨ for free, installed with --install-completion
// Now pass the NAME argument
$ python main.py Camila
Hello Camila
// It works! 🎉
Note: auto-completion works when you create a Python package and run it with --install-completion or when you use Typer CLI.
Example upgrade¶
This was the simplest example possible.
Now let's see one a bit more complex.
An example with two subcommands¶
Modify the file main.py.
Create a typer.Typer() app, and create two subcommands with their parameters.
import typer_cloup as typer
app = typer.Typer()
@app.command()
def hello(name: str):
typer.echo(f"Hello {name}")
@app.command()
def goodbye(name: str, formal: bool = False):
if formal:
typer.echo(f"Goodbye Ms. {name}. Have a good day.")
else:
typer.echo(f"Bye {name}!")
if __name__ == "__main__":
app()
And that will:
- Explicitly create a
typer.Typerapp.- The previous
typer.runactually creates one implicitly for you.
- The previous
- Add two subcommands with
@app.command(). - Execute the
app()itself, as if it was a function (instead oftyper.run).
Run the upgraded example¶
// Check the --help
$ python main.py --help
Usage: main.py [OPTIONS] COMMAND [ARGS]...
Options:
--help Show this message and exit.
Commands:
goodbye
hello
// You have 2 subcommands (the 2 functions): goodbye and hello
// Now get the --help for hello
$ python main.py hello --help
Usage: main.py hello [OPTIONS] NAME
Arguments:
NAME [required]
Options:
--help Show this message and exit.
// And now get the --help for goodbye
$ python main.py goodbye --help
Usage: main.py goodbye [OPTIONS] NAME
Arguments:
NAME [required]
Options:
--formal / --no-formal [default: no-formal]
--help Show this message and exit.
// Automatic --formal and --no-formal for the bool option 🎉
// And if you use it with the hello command
$ python main.py hello Camila
Hello Camila
// And with the goodbye command
$ python main.py goodbye Camila
Bye Camila!
// And with --formal
$ python main.py goodbye --formal Camila
Goodbye Ms. Camila. Have a good day.
Recap¶
In summary, you declare once the types of parameters (CLI arguments and CLI options) as function parameters.
You do that with standard modern Python types.
You don't have to learn a new syntax, the methods or classes of a specific library, etc.
Just standard Python 3.7+.
For example, for an int:
total: int
or for a bool flag:
force: bool
And similarly for files, paths, enums (choices), etc. And there are tools to create groups of subcommands, add metadata, extra validation, etc.
You get: great editor support, including completion and type checks everywhere.
Your users get: automatic --help, auto-completion in their terminal (Bash, Zsh, Fish) when they install your package or when using Typer CLI.
For a more complete example including more features, see the Tutorial - User Guide.
Optional Dependencies¶
Typer uses Cloup internally, which is based on Click. That's the only dependency.
But you can also install extras:
colorama: and Click will automatically use it to make sure your terminal's colors always work correctly, even in Windows.docstring_parser: and Typer will automatically use it to parse help text for parameters from docstrings of functions.
You can install typer-cloup with all optional dependencies by running pip install typer-cloup[all].
Other tools and plug-ins¶
Click has many plug-ins available that you can use. And there are many tools that help with command-line applications that you can use as well, even if they are not related to Typer or Click.
For example:
click-spinner: to show the user that you are loading data. A Click plug-in.- There are several other Click plug-ins at click-contrib that you can explore.
tabulate: to automatically display tabular data nicely. Independent of Click or Typer.tqdm: a fast, extensible progress bar, alternative to Typer's owntyper.progressbar().
License¶
This project is licensed under the terms of the MIT license.