Updated get_group and get_group_from_info to return a Click Group object

[csr]

This PR seeks to solve tiangolo#96 [BUG] typer.main.get_group should return a click.Group by having typer.main.get_group and typer.main.get_group_from_info return a click.Group instead of a click.Command. There may be some issues with this solution - I'll add some comments to the changes using the review tools here.

I tested the code with this script using Typer:

import typer

app = typer.Typer()


@app.callback()
def callback():
    """ My partially-upgraded-to-Typer app """

# insert some fancy new Typer commands here


click_group = typer.main.get_group(app)


@click_group.command()
def some_old_click_function():
      """ I need to rewrite this somday """

All tests pass locally with 100% coverage. Running mypy on this script with mypy main.py returns

Success: no issues found in 1 source file

Once again, this PR is just looking for initial feedback (criticism on code, styling, logic is especially appreciated).

Does Typer have a standard template for PR? Also, we may want to add codecov-io to this repository if it's possible to check for code coverage. I'm also curious as to why the initial tests didn't catch the bug - maybe we could write an additional test with something similar to the script above?

[csr]

I've renamed from click_command to click_group mainly because otherwise it would return Incompatible types in assignment (expression has type "Command", variable has type "Group"). Seems to be a scope issue?

[juped]

It's a type error! My understanding is that Group is more specific than Command, and this function returns a Command. So you'd probably want to cast the result of get_group.

[csr]

@juped Thank you.

Do you suggest making so that main.get_group returns a click.Group (I believe this is a requirement for mypy to run successfully)? By looking at the example code in the issue page, the user was calling get_group from their script, so I'm assuming for mypy to run successfully we need main.get_group to return a click.Group?

If yes, then I'm trying to figure out how to cast the result of main.get_group_from_info (which is what main.get_group is calling) from click.Command to click.Group. Is this how you do it in Python:

def get_group(typer_instance: Typer) -> click.Group:
    group = click.Group(get_group_from_info(TyperInfo(typer_instance)))
    return group

Thank you!

[juped]

This is at the type hinting level, where I believe it's cast().

[csr]

I tried using return cast(click.Group, group) in main.get_group (this requires an import of cast from the typing module), like this:

def get_group(typer_instance: Typer) -> click.Command:
    group = get_group_from_info(TyperInfo(typer_instance))
    return cast(click.Group, group)

However when I run mypy on the sample script in the issue I get

main.py:16: error: "Command" has no attribute "command"
Found 1 error in 1 file (checked 1 source file)

which isn't that helpful as line 16 is just a series of imports. Mmm...

[csr]

So from the Click docs cls is the the argument class to instantiate (which, from my understanding, that could be a Command or a Group). I believe this change will basically create groups of single commands instead of creating a group or a command depending on what you need. If you need just a command, then it may not make sense to create a group (extra information in memory), but I'm not too sure.

[juped]

I'm not sure of this one (don't know enough about the Click internals).