CLI Options with Help¶
You already saw how to add a help text for CLI arguments with the help parameter.
Let's now do the same for CLI options:
import typer
from typing_extensions import Annotated
def main(
name: str,
lastname: Annotated[str, typer.Option(help="Last name of person to greet.")] = "",
formal: Annotated[bool, typer.Option(help="Say hi formally.")] = False,
):
"""
Say hi to NAME, optionally with a --lastname.
If --formal is used, say hi very formally.
"""
if formal:
print(f"Good day Ms. {name} {lastname}.")
else:
print(f"Hello {name} {lastname}")
if __name__ == "__main__":
typer.run(main)
Tip
Prefer to use the Annotated version if possible.
import typer
def main(
name: str,
lastname: str = typer.Option("", help="Last name of person to greet."),
formal: bool = typer.Option(False, help="Say hi formally."),
):
"""
Say hi to NAME, optionally with a --lastname.
If --formal is used, say hi very formally.
"""
if formal:
print(f"Good day Ms. {name} {lastname}.")
else:
print(f"Hello {name} {lastname}")
if __name__ == "__main__":
typer.run(main)
The same way as with typer.Argument(), we can put typer.Option() inside of Annotated.
We can then pass the help keyword parameter:
lastname: Annotated[str, typer.Option(help="this option does this and that")] = ""
...to create the help for that CLI option.
The same way as with typer.Argument(), Typer also supports the old style using the function parameter default value:
lastname: str = typer.Option(default="", help="this option does this and that")
Copy that example from above to a file main.py.
Test it:
CLI Options help panels¶
The same as with CLI arguments, you can put the help for some CLI options in different panels to be shown with the --help option.
If you have installed Rich as described in the docs for Printing and Colors, you can set the rich_help_panel parameter to the name of the panel you want for each CLI option:
import typer
from typing_extensions import Annotated
def main(
name: str,
lastname: Annotated[str, typer.Option(help="Last name of person to greet.")] = "",
formal: Annotated[
bool,
typer.Option(
help="Say hi formally.", rich_help_panel="Customization and Utils"
),
] = False,
debug: Annotated[
bool,
typer.Option(
help="Enable debugging.", rich_help_panel="Customization and Utils"
),
] = False,
):
"""
Say hi to NAME, optionally with a --lastname.
If --formal is used, say hi very formally.
"""
if formal:
print(f"Good day Ms. {name} {lastname}.")
else:
print(f"Hello {name} {lastname}")
if __name__ == "__main__":
typer.run(main)
Tip
Prefer to use the Annotated version if possible.
import typer
def main(
name: str,
lastname: str = typer.Option("", help="Last name of person to greet."),
formal: bool = typer.Option(
False, help="Say hi formally.", rich_help_panel="Customization and Utils"
),
debug: bool = typer.Option(
False, help="Enable debugging.", rich_help_panel="Customization and Utils"
),
):
"""
Say hi to NAME, optionally with a --lastname.
If --formal is used, say hi very formally.
"""
if formal:
print(f"Good day Ms. {name} {lastname}.")
else:
print(f"Hello {name} {lastname}")
if __name__ == "__main__":
typer.run(main)
Now, when you check the --help option, you will see a default panel named "Options" for the CLI options that don't have a custom rich_help_panel.
And below you will see other panels for the CLI options that have a custom panel set in the rich_help_panel parameter:
Here we have a custom CLI options panel named "Customization and Utils".
Help with style using Rich¶
In a future section you will see how to use custom markup in the help for CLI options when reading about Commands - Command Help.
If you are in a hurry you can jump there, but otherwise, it would be better to continue reading here and following the tutorial in order.
Hide default from help¶
You can tell Typer to not show the default value in the help text with show_default=False:
import typer
from typing_extensions import Annotated
def main(fullname: Annotated[str, typer.Option(show_default=False)] = "Wade Wilson"):
print(f"Hello {fullname}")
if __name__ == "__main__":
typer.run(main)
Tip
Prefer to use the Annotated version if possible.
import typer
def main(fullname: str = typer.Option("Wade Wilson", show_default=False)):
print(f"Hello {fullname}")
if __name__ == "__main__":
typer.run(main)
And it will no longer show the default value in the help text:
Technical Details
In Click applications the default values are hidden by default. 🙈
In Typer these default values are shown by default. 👀
Custom default string¶
You can use the same show_default to pass a custom string (instead of a bool) to customize the default value to be shown in the help text:
import typer
from typing_extensions import Annotated
def main(
fullname: Annotated[
str, typer.Option(show_default="Deadpoolio the amazing's name")
] = "Wade Wilson",
):
print(f"Hello {fullname}")
if __name__ == "__main__":
typer.run(main)
Tip
Prefer to use the Annotated version if possible.
import typer
def main(
fullname: str = typer.Option(
"Wade Wilson", show_default="Deadpoolio the amazing's name"
),
):
print(f"Hello {fullname}")
if __name__ == "__main__":
typer.run(main)
And it will be used in the help text: