I have a C# switch and I need to call a method before each case returns. Is there any way I could simplify this?

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?

There is not even one call to "await NoSelected" in your Code. — Holger, Nov 21 '19 at 13:33
By `await NoSelected` do you mean `await ShowFirstMessageAsync`? — Sweeper, Nov 21 '19 at 13:35
Sorry I did a copy / paste and it looks like the copy didn't work. Blame my MacBook Air keyboard for that ;-( — Alan2, Nov 21 '19 at 13:35

score 11 · Accepted Answer · answered Nov 21 '19 at 13:38

11

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();
}

answered Nov 21 '19 at 13:38

Sweeper

213,210
22
193
313

Very impressive ! – Alan2 Nov 21 '19 at 13:43
Just upgraded to C# 8 and testing this out now. I will try to use expressions more often and hopefully your answer will be a good help to others who have been wondering how they could be used. – Alan2 Nov 21 '19 at 13:54

score 2 · Answer 2 · answered Nov 21 '19 at 13:35

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();
}

answered Nov 21 '19 at 13:35

Johnathan Barclay

18,599
1
22
35

This looks good. Is it needed to set showFirstMessage = false; as I think the default would be false? – Alan2 Nov 21 '19 at 13:38
you could use c# switch expression to set the showFirstMessage :) – Bambuk Nov 21 '19 at 13:39
@Bambuk - can you give an example of what you mean – Alan2 Nov 21 '19 at 13:42
@Alan2 no, it would be unassigned otherwise. Sweeper's answer is better though if you can use C#8. – Johnathan Barclay Nov 21 '19 at 13:49

I have a C# switch and I need to call a method before each case returns. Is there any way I could simplify this?

2 Answers2