Unexpected locale-aware string conversions cause problems when calling commands with float variables as arguments in some locales

[fmoo]

What is the current behavior?

When using custom commands that expect float parameters in yarn, e.g., <<sleep>> float literals (e.g., <<sleep 0.5>>) behave as expected. However, when using variables (such as <<sleep {$delay}>> in a locale that uses "." as a thousands separator, such as de-AT, the float is converted to a locale aware string (e.g., "0,5") but then back to a float using an InvariantCulture when calling the custom command.

Please provide the steps to reproduce, and if possible a minimal demo of the problem:

Run the following in an OnAwake() somewhere to force the system locale to German (AT).

using System.Globalization;
// ...
        void Awake() {
            Thread.CurrentThread.CurrentCulture = new CultureInfo("de-AT");
            Thread.CurrentThread.CurrentUICulture = new CultureInfo("de-AT");
        }

Then in a yarn script:

<<declare $delay = 0.5>>
Let's wait for a half-second...
<<wait {$delay}>>
Done!

The "Done" dialogue will take 5 seconds to appear instead of 0.5 seconds.

What is the expected behavior?

Since we are using a properly typed float variable, and passing it to a command that expects a float, I expect there to be no unnecessary computations of string formatting or parsing to happen, and the "Done" dialogue to appear after a half-second delay instead of five seconds.

Locale aware string formatting would still be expected when using {$value} to format a float var into user-visible dialogue, as well as commands that expect strings/text but a float was passed.

Please tell us about your environment:

• Yarn Spinner Version: 2.2.1+ (0d39162)
• Unity Version: 2019.4.36f1

Other information
Link to discord discussion in #help

[McJones]

This was partially fixed as referenced in YarnSpinnerTool/YarnSpinner#369 but the long term issue persists.
For now the format_invariant method provides a workaround until we can come to some long term solution.