trogon do not supports python3.9 due to the use of '|' Union operator

[juguerre]

Just doing some initial integration with a typer command line using python 3.9 and I get this error:

Traceback (most recent call last):
  File "/home/juguerre/.local/share/uv/python/cpython-3.9.21-linux-x86_64-gnu/lib/python3.9/runpy.py", line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/home/juguerre/.local/share/uv/python/cpython-3.9.21-linux-x86_64-gnu/lib/python3.9/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/home/juguerre/dev/repos/elasticcsv/elasticcsv/csv2es.py", line 8, in <module>
    from trogon.typer import init_tui
  File "/home/juguerre/dev/repos/elasticcsv/.venv/lib/python3.9/site-packages/trogon/typer.py", line 13, in <module>
    def init_tui(app: typer.Typer, name: str | None = None):
TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'

Documentation claims that python 3.9 is supported and it seems that is not the case.

Tested on kubuntu 24.04
trogon v0.6.0

Thanks

[martinhoyer]

To be fair, the pipe expression for Union has been introduced in Python 3.10. Your code probably uses future

[JLowe-N]

It looks like the current state of main branch adds

from __future__ import annotations

to typer.py

Otherwise in Python versions below 3.10.0, the type annotation for init_tui fails due to using the Union operator.

https://github.com/Textualize/trogon/blob/v0.6.0/trogon/typer.py#L13

def init_tui(app: typer.Typer, name: str | None = None):

In Trogon tag 0.6.0, this is still unresolved. In Trogon main, this looks to be resolved.

This worked for me as a workaround:

### -- snip --- app defined above here ###
from trogon.trogon import Trogon
import click

def init_tui(app: typer.Typer, name = None):
    def wrapped_tui():
        Trogon(
            typer.main.get_group(app),
            app_name=name,
            click_context=click.get_current_context(),
        ).run()

    app.command("tui", help="Open Textual TUI.")(wrapped_tui)

    return app

init_tui(app)

This is a redefinition of init_tui from trogon.typer, without the Python 3.10 style type hints.
Adding from __future__ import annotations was not enough to resolve the issue.