typer/README.md
2022-07-12 16:45:43 +00:00

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<p align="center">
<a href="https://typer.tiangolo.com"><img src="https://typer.tiangolo.com/img/logo-margin/logo-margin-vector.svg" alt="Typer"></a>
</p>
<p align="center">
<em>Typer, build great CLIs. Easy to code. Based on Python type hints.</em>
</p>
<p align="center">
<a href="https://github.com/tiangolo/typer/actions?query=workflow%3ATest" target="_blank">
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<img src="https://github.com/tiangolo/typer/workflows/Publish/badge.svg" alt="Publish">
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---
**Documentation**: <a href="https://typer.tiangolo.com" target="_blank">https://typer.tiangolo.com</a>
**Source Code**: <a href="https://github.com/tiangolo/typer" target="_blank">https://github.com/tiangolo/typer</a>
---
Typer is a library for building <abbr title="command line interface, programs executed from a terminal">CLI</abbr> applications that users will **love using** and developers will **love creating**. Based on Python 3.6+ type hints.
The key features are:
* **Intuitive to write**: Great editor support. <abbr title="also known as auto-complete, autocompletion, IntelliSense">Completion</abbr> 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
<a href="https://fastapi.tiangolo.com" target="_blank"><img src="https://fastapi.tiangolo.com/img/logo-margin/logo-teal.png" style="width: 20%;"></a>
**Typer** is <a href="https://fastapi.tiangolo.com" class="external-link" target="_blank">FastAPI</a>'s little sibling.
And it's intended to be the FastAPI of CLIs.
## Requirements
Python 3.6+
**Typer** stands on the shoulders of a giant. Its only internal dependency is <a href="https://click.palletsprojects.com/" class="external-link" target="_blank">Click</a>.
## Installation
<div class="termy">
```console
$ pip install "typer[all]"
---> 100%
Successfully installed typer
```
</div>
**Note**: that will include <a href="https://rich.readthedocs.io/" class="external-link" target="_blank">Rich</a>. Rich is the recommended library to *display* information on the terminal, it is optional, but when installed, it's deeply integrated into **Typer** to display beautiful output.
## Example
### The absolute minimum
* Create a file `main.py` with:
```Python
import typer
def main(name: str):
print(f"Hello {name}")
if __name__ == "__main__":
typer.run(main)
```
### Run it
Run your application:
<div class="termy">
```console
// Run your application
$ python main.py
// You get a nice error, you are missing NAME
<font color="#F4BF75">Usage: </font>main.py [OPTIONS] NAME
<font color="#A5A5A1">Try </font><font color="#44919F">&apos;main.py </font><font color="#44919F"><b>--help</b></font><font color="#44919F">&apos;</font><font color="#A5A5A1"> for help.</font>
<font color="#F92672">╭─ Error ───────────────────────────────────────────╮</font>
<font color="#F92672">│</font> Missing argument &apos;NAME&apos;. <font color="#F92672">│</font>
<font color="#F92672">╰───────────────────────────────────────────────────╯</font>
// You get a --help for free
$ python main.py --help
<b> </b><font color="#F4BF75"><b>Usage: </b></font><b>main.py [OPTIONS] NAME </b>
<b> </b>
<font color="#A5A5A1">╭─ Arguments ───────────────────────────────────────╮</font>
<font color="#A5A5A1">│ </font><font color="#F92672">*</font> name <font color="#F4BF75"><b>TEXT</b></font> [default: None] <font color="#A6194C">[required]</font> │
<font color="#A5A5A1">╰───────────────────────────────────────────────────╯</font>
<font color="#A5A5A1">╭─ Options ─────────────────────────────────────────╮</font>
<font color="#A5A5A1">│ </font><font color="#A1EFE4"><b>--install-completion</b></font> Install completion │
<font color="#A5A5A1">│ for the current │</font>
<font color="#A5A5A1">│ shell. │</font>
<font color="#A5A5A1">│ </font><font color="#A1EFE4"><b>--show-completion</b></font> Show completion for │
<font color="#A5A5A1">│ the current shell, │</font>
<font color="#A5A5A1">│ to copy it or │</font>
<font color="#A5A5A1">│ customize the │</font>
<font color="#A5A5A1">│ installation. │</font>
<font color="#A5A5A1">│ </font><font color="#A1EFE4"><b>--help</b></font> Show this message │
<font color="#A5A5A1">│ and exit. │</font>
<font color="#A5A5A1">╰───────────────────────────────────────────────────╯</font>
// 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! 🎉
```
</div>
**Note**: auto-completion works when you create a Python package and run it with `--install-completion` or when you use <a href="https://typer.tiangolo.com/typer-cli/" class="internal-link" target="_blank">Typer CLI</a>.
## 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.
```Python hl_lines="3 6 11 20"
import typer
app = typer.Typer()
@app.command()
def hello(name: str):
print(f"Hello {name}")
@app.command()
def goodbye(name: str, formal: bool = False):
if formal:
print(f"Goodbye Ms. {name}. Have a good day.")
else:
print(f"Bye {name}!")
if __name__ == "__main__":
app()
```
And that will:
* Explicitly create a `typer.Typer` app.
* The previous `typer.run` actually creates one implicitly for you.
* Add two subcommands with `@app.command()`.
* Execute the `app()` itself, as if it was a function (instead of `typer.run`).
### Run the upgraded example
Check the new help:
<div class="termy">
```console
$ python main.py --help
<b> </b><font color="#F4BF75"><b>Usage: </b></font><b>main.py [OPTIONS] COMMAND [ARGS]... </b>
<b> </b>
<font color="#A5A5A1">╭─ Options ─────────────────────────────────────────╮</font>
<font color="#A5A5A1">│ </font><font color="#A1EFE4"><b>--install-completion</b></font> Install completion │
<font color="#A5A5A1">│ for the current │</font>
<font color="#A5A5A1">│ shell. │</font>
<font color="#A5A5A1">│ </font><font color="#A1EFE4"><b>--show-completion</b></font> Show completion for │
<font color="#A5A5A1">│ the current shell, │</font>
<font color="#A5A5A1">│ to copy it or │</font>
<font color="#A5A5A1">│ customize the │</font>
<font color="#A5A5A1">│ installation. │</font>
<font color="#A5A5A1">│ </font><font color="#A1EFE4"><b>--help</b></font> Show this message │
<font color="#A5A5A1">│ and exit. │</font>
<font color="#A5A5A1">╰───────────────────────────────────────────────────╯</font>
<font color="#A5A5A1">╭─ Commands ────────────────────────────────────────╮</font>
<font color="#A5A5A1">│ </font><font color="#A1EFE4"><b>goodbye </b></font> │
<font color="#A5A5A1">│ </font><font color="#A1EFE4"><b>hello </b></font> │
<font color="#A5A5A1">╰───────────────────────────────────────────────────╯</font>
// You have 2 subcommands (the 2 functions): goodbye and hello
```
</div>
Now check the help for the `hello` command:
<div class="termy">
```console
$ python main.py hello --help
<b> </b><font color="#F4BF75"><b>Usage: </b></font><b>main.py hello [OPTIONS] NAME </b>
<b> </b>
<font color="#A5A5A1">╭─ Arguments ───────────────────────────────────────╮</font>
<font color="#A5A5A1">│ </font><font color="#F92672">*</font> name <font color="#F4BF75"><b>TEXT</b></font> [default: None] <font color="#A6194C">[required]</font> │
<font color="#A5A5A1">╰───────────────────────────────────────────────────╯</font>
<font color="#A5A5A1">╭─ Options ─────────────────────────────────────────╮</font>
<font color="#A5A5A1">│ </font><font color="#A1EFE4"><b>--help</b></font> Show this message and exit. │
<font color="#A5A5A1">╰───────────────────────────────────────────────────╯</font>
```
</div>
And now check the help for the `goodbye` command:
<div class="termy">
```console
$ python main.py goodbye --help
<b> </b><font color="#F4BF75"><b>Usage: </b></font><b>main.py goodbye [OPTIONS] NAME </b>
<b> </b>
<font color="#A5A5A1">╭─ Arguments ───────────────────────────────────────╮</font>
<font color="#A5A5A1">│ </font><font color="#F92672">*</font> name <font color="#F4BF75"><b>TEXT</b></font> [default: None] <font color="#A6194C">[required]</font> │
<font color="#A5A5A1">╰───────────────────────────────────────────────────╯</font>
<font color="#A5A5A1">╭─ Options ─────────────────────────────────────────╮</font>
<font color="#A5A5A1">│ </font><font color="#A1EFE4"><b>--formal</b></font> <font color="#AE81FF"><b>--no-formal</b></font> [default: no-formal] │
<font color="#A5A5A1">│ </font><font color="#A1EFE4"><b>--help</b></font> Show this message │
<font color="#A5A5A1">│ and exit. │</font>
<font color="#A5A5A1">╰───────────────────────────────────────────────────╯</font>
// Automatic --formal and --no-formal for the bool option 🎉
```
</div>
Now you can try out the new command line application:
<div class="termy">
```console
// 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.
```
</div>
### 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 3.6+**.
For example, for an `int`:
```Python
total: int
```
or for a `bool` flag:
```Python
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, PowerShell) when they install your package or when using <a href="https://typer.tiangolo.com/typer-cli/" class="internal-link" target="_blank">Typer CLI</a>.
For a more complete example including more features, see the <a href="https://typer.tiangolo.com/tutorial/">Tutorial - User Guide</a>.
## Optional Dependencies
Typer uses <a href="https://click.palletsprojects.com/" class="external-link" target="_blank">Click</a> internally. That's the only dependency.
But you can also install extras:
* <a href="https://rich.readthedocs.io/en/stable/index.html" class="external-link" target="_blank"><code>rich</code></a>: and Typer will show nicely formatted errors automatically.
* <a href="https://github.com/sarugaku/shellingham" class="external-link" target="_blank"><code>shellingham</code></a>: and Typer will automatically detect the current shell when installing completion.
* With `shellingham` you can just use `--install-completion`.
* Without `shellingham`, you have to pass the name of the shell to install completion for, e.g. `--install-completion bash`.
You can install `typer` with `rich` and `shellingham` with `pip install typer[all]`.
## License
This project is licensed under the terms of the MIT license.