spectre.console/src/Spectre.Console.Cli/FlagValue.cs

namespace Spectre.Console.Cli;

/// <summary>
/// Implementation of a flag with an optional value.
/// </summary>
/// <typeparam name="T">The flag's element type.</typeparam>
public sealed class FlagValue<T> : IFlagValue
{
    /// <summary>
    /// Gets or sets a value indicating whether or not the flag was set or not.
    /// </summary>
    public bool IsSet { get; set; }

#pragma warning disable CS8618 // Non-nullable field is uninitialized. Consider declaring as nullable.
    /// <summary>
    /// Gets or sets the flag's value.
    /// </summary>
    public T Value { get; set; }
#pragma warning restore CS8618 // Non-nullable field is uninitialized. Consider declaring as nullable.

    /// <inheritdoc/>
    Type IFlagValue.Type => typeof(T);

    /// <inheritdoc/>
    object? IFlagValue.Value
    {
        get => Value;
        set
        {
#pragma warning disable CS8601 // Possible null reference assignment.
#pragma warning disable CS8600 // Converting null literal or possible null value to non-nullable type.
            Value = (T)value;
#pragma warning restore CS8600 // Converting null literal or possible null value to non-nullable type.
#pragma warning restore CS8601 // Possible null reference assignment.
        }
    }

    /// <inheritdoc/>
    public override string ToString()
    {
        var flag = (IFlagValue)this;
        if (flag.Value != null)
        {
            return string.Format(
                CultureInfo.InvariantCulture,
                "Set={0}, Value={1}",
                IsSet,
                flag.Value.ToString());
        }

        return string.Format(
            CultureInfo.InvariantCulture,
            "Set={0}", IsSet);
    }
}