flag_value converted to str in Click 8

[jwodder]

Consider the following code:

import click

@click.command()
@click.option("--answer", flag_value=42)
def main(answer):
    click.echo(repr(answer))

if __name__ == '__main__':
    main()

Under click 7, passing the --answer option to this script prints 42 (an int), as expected. Under click 8, it prints '42' (a str).

Environment:

• Python version: 3.9.5
• Click version: 7.1.2 vs. 8.0.0

[davidism]

The default type of parameters is str. You need to specify type=int if you want int values.

[jwodder]

@davidism OK, but in my actual use case, the flag_value is an instance of a class with a zero-argument constructor. How am I expected to get that to work? Trying @click.option("--answer", is_flag=True, type=Klass) (and also with flag_value=None) results in a Klass() takes no arguments TypeError.

[davidism]

Then it should use type=click.UNPROCESSED to pass the value through unchanged.

[davidism]

I think what's affecting this is that we now apply type casting consistently to any value coming through the pipeline. I wonder if setting the type to unprocessed automatically for flag values is safe.

[jwodder]

@davidism Using type=click.UNPROCESSED works, thanks.

[davidism]

Which is a callable, not a literal value.

[ThiefMaster]

A callable is dynamic...

[davidism]

@crashfrog sorry, it sounds like we're having trouble explaining the difference. You're going to have to trust us that there is, in fact, a difference, this tangent is derailing this issue.