switch Expression as a replacement for "if" statements

[TonyValenti]

The switch expression is a really nice replacement for some if statements, however, sometimes it can be verbose when you do things like this:

                var Status = false switch {
                    _ when Input.MatterStage.AsText().Equals("Intake") => PacketStatus.Prospective,
                    _ when Input.MatterStage.AsText().Equals("Closed") => PacketStatus.Archived,
                    _ => PacketStatus.Active,
                };

It would be nice if you could switch on _ and then omit the _ when in the expression:

                var Status = _ switch {
                    Input.MatterStage.AsText().Equals("Intake") => PacketStatus.Prospective,
                    Input.MatterStage.AsText().Equals("Closed") => PacketStatus.Archived,
                    _ => PacketStatus.Active,
                };

[mburbea]

I assume you find the already existing terse syntax unappealing?

var status = Input.MatterStage.AsText().Equals("Intake") ? PacketStatus.Prospective
    : Input.MatterStage.AsText().Equals("Closed") ? PacketStatus.Archived
    : PacketStatus.Active;

[TonyValenti]

Correct. I don't like that syntax at all.

[CyrusNajmabadi]

the ternary expression form seems equally readable (and nice and concise):

 var Status = _ switch
{
    Input.MatterStage.AsText().Equals("Intake") => PacketStatus.Prospective,
    Input.MatterStage.AsText().Equals("Closed") => PacketStatus.Archived,
    _ => PacketStatus.Active,
};

vs

var status =
    Input.MatterStage.AsText().Equals("Intake") ? PacketStatus.Prospective :
    Input.MatterStage.AsText().Equals("Closed") ? PacketStatus.Archived :
    PacketStatus.Active;

each case and each result is easy to make out. i don't see much value in => over ? here.

[huoyaoyuan]

Rust-like block expression is also useful here:

var status = if (Input.MatterStage.AsText().Equals("Intake"))
{
    PacketStatus.Prospective
}
else if (Input.MatterStage.AsText().Equals("Closed"))
{
    PacketStatus.Archived
}
else
{
    PacketStatus.Active
};

[spydacarnage]

Can't you use this?

var Status = Input.MatterStage.AsText() switch {
    "Intake" => PacketStatus.Prospective,
    "Closed" => PacketStatus.Archived,
    _ => PacketStatus.Active,
};

[tacosontitan]

Personally, I'd use a dictionary for such matters to promote scalability while improving debugability and making the concern of my code being terse an obsolete thought:

private static readonly Dictionary<string, PacketStatus> _mappings = new(capacity: 2)
{
    { "Intake", PacketStatus.Prospective },
    { "Closed", PacketStatus.Archived }
};

...
var matterStage = Input.MatterStage.AsText();
if (_mappings.TryGetValue(matterStage, out var status))
    return status;

return PacketStatus.Active;

[nathan130200]

If you know all the values you will receive, definitely a Dictionary mapping or a readonly struct can be convenient in this context.

[DebuggerDisplay("{Name,nq}")] // show nice in debugger.
public readonly struct LogLevel 
{
	// .NET don't allow us seal struct, so parameterless constructor must exists unfortunately.
	public LogLevel()
	{
	}
	
	// Only specific values are allowed
	LogLevel(char shortName, string fullName) 
	{
		ShortName = shortName;
		Name = fullName;
	}
	
	public char ShortName { get; }
	public string Name {get; }
	
	public static LogLevel Information { get; } = new ('I', nameof(Information));
	// ...other values...
	public static LogLevel Verbose { get; } = new ('V', nameof(Verbose));

        // add comparation, if ShortName == (char)0 then its invalid LogLevel value.
        // or create separated field to handle all Unknown values.
        // IEnumerable<LogLevel> Values to map all values.
}

Something like i did in my lobby server emulation for an game. The player class must have both ID 0~4 and Flags (combined: 1 << ID) instead seaparate in to two enums i just created an struct that holds both, ID and Flag value from that player class only. And created an method called HasFlag(int value) that simulates flag checking in int value. Also i've added bitwise operators to that struct, that always return int for OR and AND operations.