Using Annotated on Lists leads to crash

[secretrobotron]

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Example Code

import typer
from typing import List
from typing_extensions import Annotated

app = typer.Typer()

@app.command()
def test1(test_list: List[int] = typer.Option(default=[1, 2, 3, 4])) -> None:
    for i in test_list:
        print(i)

@app.command()
def test2(test_list: Annotated[List[int], typer.Option(default=[1, 2, 3, 4])]) -> None:
     for i in test_list:
         print(i)

app()

Description

While trying to work around this problem, I ran into a new one. I have (I think) used Annotated correctly, but when I run the example code, I get this error:

AttributeError: 'list' object has no attribute 'isidentifier'

If I comment out test2, it works fine.

The traceback suggests the problem might be within Click, but I'm unsure:

 site-packages/click/core.py:2651 in _parse_decls  

Operating System

macOS

Operating System Details

No response

Typer Version

0.9.4

Python Version

3.11.7

Additional Context

Similar issues:

• TypeError - <argument/option name> is defined twice #834
• Weird behavior when wrongly combining `Annotated` with `List` #713

[svlandeg]

Hi!

You have to declare the default value slightly differently with Annotated. This should work as expected:

import typer
from typing import List
from typing_extensions import Annotated

app = typer.Typer()


@app.command()
def test2(test_list: Annotated[List[int], typer.Option()] = [1, 2, 3, 4]) -> None:
    for i in test_list:
        print(i)


if __name__ == "__main__":
    typer.run(test2)

[ShihaoXu]

Hi, the line

def test2(test_list: Annotated[List[int], typer.Option()] = [1, 2, 3, 4]) -> None:

isn't a perfect solution for the question.
I have two follow up questions:

1. [1, 2, 3, 4] is only initialized once and the same list would be used whenever test2 is called. How can we defined a default_factory for the annotated function parameter?
2. It seems that var: Annotated[X, typer.Option(default=Y)] behaves differently than var: Annotated[X, typer.Option()] = Y in some situations. Is it a desired behavior?

[YuriiMotov]

How can we defined a default_factory for the annotated function parameter?

You can specify default factory as:

def test2(test_list: Annotated[List[int], typer.Option(default_factory=lambda: [1, 2, 3, 4])]) -> None:

It seems that var: Annotated[X, typer.Option(default=Y)] behaves differently than var: Annotated[X, typer.Option()] = Y in some situations.

Could you please clarify what situations you are talking about?

[thht]

I think I have a similar situation here. The following code runs fine when using typer 0.16 and pinning click to <8.2 but fails with TypeError: Secondary flag is not valid for non-boolean flag. on click >=8.2. I hunted it down a bit: Apparently, typer just forwards the default_factory as the default value so the type for click ends up being STRING, which then leads to the confusion.

def get_hashed_default() -> bool:
    config = Config.from_cmdargs()  # This needs typer initialized to work. So we need the default to be a callable.
    return config.hash_subject_ids

@app.command
def foo(hash_subject_ids: Annotated[bool, typer.Option(
        help='Whether to hash the subject IDs. Overrides the `hash_subject_ids` setting.',
        default_factory=get_hashed_default,
        show_default=False,
        ),
    ]
)

[svlandeg]

@thht : that sounds like a different issue, thanks for the report! We'll look into it.

[svlandeg]

@thht : I can't immediately replicate, can you give a full code file that works, the command you ran and the exact output you're getting?

[saandaar]

Install dependencies:

pip install typer==0.16.1 click==8.2.2

Example script:

import typer
from typing_extensions import Annotated

app = typer.Typer()

def get_default_bool() -> bool:
    """A simple default factory that returns a boolean."""
    return True

@app.command()
def test_command(
    flag: Annotated[bool, typer.Option(
        "--flag/--no-flag",
        help="A boolean flag with default_factory",
        default_factory=get_default_bool,
        show_default=False,
    )]
):
    """Test command that reproduces the Click/Typer compatibility issue."""
    print(f"Flag value: {flag}")

if __name__ == "__main__":
    app()

Run script:

python test.py test-command --help

# Output
# ...
# TypeError: Secondary flag is not valid for non-boolean flag.

[svlandeg]

@saandaar: thanks! This code snippet runs fine for me with both Click 8.1.8 and 8.2.1 and indeed crashes with 8.2.2. You should update your click version, as 8.2.2 has actually been yanked due to "Unintended change in behavior of boolean options and None".

[thht]

Ok, thanks for looking into it!