我有一个 C# 开关，我需要在每个案例返回之前调用一个方法。 有什么办法可以简化这个吗？

Question

I have this code which I refactored to use a switch but it still looks very clumsy. Now I am looking for a way to simplify it.

    public async Task CheckAvailability()
    {
        switch (Settings.Mode)
        {
            case Enums.MO.Learn:
                if (await IsLearn())
                {
                    await ShowFirstMessageAsync();
                    return;
                }
                break;
            case Enums.MO.Practice:
                if (await IsPractice())
                {
                    await ShowFirstMessageAsync();
                    return;
                }
                break;
            case Enums.MO.Quiz:
                if (await IsQuiz())
                {
                    await ShowFirstMessageAsync();
                    return;
                }
                break;
            default:
                break;
        }

        await PickCard();
    }

Is there anyone that can think of a simpler way to implement this without the need for multiple calls to await ShowFirstMessageAsync?

Answer 1

This is a good opportunity to use switch expressions in C# 8:

var shouldShowFirstMessage = Settings.Mode switch
{
    Enums.MO.Learn => await IsLearn(),
    Enums.MO.Practice => await IsPractice(),
    Enums.MO.Quiz => await IsQuiz(),
    _ => false
}
if (shouldShowFirstMessage) {
    await ShowFirstMessageAsync();
} else {
    await PickCard();
}

Answer 2

Maybe this:

public async Task CheckAvailability()
{
    bool showFirstMessage = false;
    switch (Settings.Mode)
    {
        case Enums.MO.Learn:
            showFirstMessage = await IsLearn();
            break;
        case Enums.MO.Practice:
            showFirstMessage = await IsPractice();
            break;
        case Enums.MO.Quiz:
            showFirstMessage = await IsQuiz();
            break;
        default:
            break;
    }

    if (showFirstMessage)
    {
        await ShowFirstMessageAsync();
        return;
    }

    await PickCard();
}