CLI Option names are not checked for duplicates #1167

slavos1 · 2025-03-01T00:41:28Z

slavos1
Mar 1, 2025

First Check

I added a very descriptive title here.
I used the GitHub search to find a similar question and didn't find it.
I searched the Typer documentation, with the integrated search.
I already searched in Google "How to X in Typer" and didn't find any information.
I already read and followed all the tutorials in the docs and didn't find an answer.
I already checked if it is not related to Typer but to Click.

Commit to Help

I commit to help with one of those options 👆

Example Code

from typing import Annotated

import typer

app = typer.Typer(
    no_args_is_help=True,
    add_completion=False,
)


@app.command()
def _main(
    first_name: Annotated[
        str,
        typer.Option(
            "-n",
            "--first-name",
            help="First name",
        ),
    ] = "John",
    surname: Annotated[
        str,
        typer.Option(
            "-n",
            # "--first-name",
            "--surname",
            help="Surname",
        ),
    ] = "Doe",
    title: Annotated[
        str,
        typer.Option(
            "--first-name",
            "-c",
            help="Title",
        ),
    ] = "X.",
):
    typer.echo(f"{title} {first_name} {surname}")


if __name__ == "__main__":
    app()

Description

If I could I would have raised this as a bug.

It seems Typer does not check duplicate short or long Option names.

Considering the code above, this output can be seen:

python dupe-options.py --help
                                                                        
 Usage: dupe-options.py [OPTIONS]                                       
                                    
8000
                                    
╭─ Options ────────────────────────────────────────────────────────────╮
│ --first-name  -n      TEXT  First name [default: John]               │
│ --surname     -n      TEXT  Surname [default: Doe]                   │
│ --first-name  -c      TEXT  Title [default: X.]                      │
│ --help                      Show this message and exit.              │
╰──────────────────────────────────────────────────────────────────────╯

# 🆗 default values, works as expected
python dupe-options.py
X. John Doe

# 🆗 using long name, works as expected
python dupe-options.py --surname Smith
X. John Smith

# ⚠️ oops, using short name, sets "surname" instead of
# "first name" as `surname...Option('-n') is defined last
python dupe-options.py -n Murphy
X. John Murphy

# 🆗 using short name sets the "title"
python dupe-options.py -c Hon.
Hon. John Doe

# ⚠️ oops, using "--first-name" sets "title" not "first name"
# as title...Option("--first-name") is defined last
cmd [7] | python dupe-options.py --first-name Hon.
Hon. John Doe

Typer takes the last-defined option name (short or long) as the corresponding key for each Annotated function argument.

This bit me today where I had many options with defaults and had a short-name defined twice by accident but Typer did not complain.
Then I was surprised my first-defined option did not get set as expected.

Operating System

Linux

Operating System Details

No response

Typer Version

0.15.2

Python Version

Python 3.10.12

Additional Context

No response

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slavos1 Mar 1, 2025

First Check

Commit to Help

Example Code

Description

Operating System

Operating System Details

Typer Version

Python Version

Additional Context

Replies: 0 comments

slavos1
Mar 1, 2025