Support Lowercase Color Parsing or Provide Case-Insentive Suggestions

[starry48]

Currently, when setting colors in Textual, the color name must be provided in uppercase to be recognised. While using a lowercase color name (eg. "red") results in an error.

Some solutions I would suggest is:

1. Case-Insentive Parsing: The color parser is updated to recognize color namers regardless of case. In which "red", "Red" and "RED" would result in the same color.
2. Enhanced Error Suggestion: If implenting the full case-insentivity is complex, then an alternative would be to enhance the ColorParseError exception. So when an unrecognized color string is provided, the error message could check if it a lowercase version of the color matches a known uppercase color and suggests it.

For example instead of ColorParseError: "'red' is not a valid color" we could have ColorParseError: "'red' is not a valid color. Did you mean 'Red'"

This small improvement would make working with the amasing system of Textual even smoother. Thank you so much.

[TomJGooding]

Can you provide a code example to show what you mean?

For example, this code:

from textual.app import App, ComposeResult


class ExampleApp(App):
    CSS = """
    Screen{
        background: Red;
    }
    """


if __name__ == "__main__":
    ExampleApp().run()

Results in this error message:

Invalid value ('Red') for the background property. Did you mean 'red'?

[davep]

Curiously things like RED and rED result in a suggested correction, but reD and rEd do not (for example, I didn't check all the permutations).

[TomJGooding]

Strange, both reD and rEd result in the same suggestion for me in the above example?

Edit: Ah, did you mean RED and rED don't result in a suggestion? It looks like that might be due to the underlying difflib:

>>> import difflib
>>> colors = ["red", "green", "blue"]
>>> difflib.get_close_matches("RED", colors)
[]

[davep]

Arse, yeah, typed that the wrong way round (that's what you get for tinkering for 10 minutes before stepping out the door).