Vinz

C# Language Tips 2

Մι∩z•thedev · Follow Published in Coding · 6 min read · 1 day ago __ 👏65k 💬321 🔖 ⤴️ __

While investigating CQRS, I angled a couple of nice tips.

primary constructors

less typing, very convenient for dependency injection

public class QueryRoomAvailabilityService
{
    private readonly IQueryable<RoomAvailability> _roomAvailabilities;

    public QueryRoomAvailabilityService(IQueryable<RoomAvailability> roomAvailabilities)
    {
        _roomAvailabilities = roomAvailabilities;
    }
}

becomes

public class QueryRoomAvailabilityService(IQueryable<RoomAvailability> roomAvailabilities)
{

}

but unhandy when the class inherits a base constructor.

compare strings insensitive to case and diacritics

public int? FindHotel(string hotelName, bool approx)
{
	var exactMatch = back.Hotels

		.FirstOrDefault(hotel => 0 == string.Compare(
			hotel.HotelName,
			hotelName,
			CultureInfo.CurrentCulture, 
			CompareOptions.IgnoreCase | CompareOptions.IgnoreNonSpace | CompareOptions.IgnoreSymbols))

		?.HotelId;

	if (exactMatch != default)
	{
		return exactMatch;
	}

	if (!approx)
	{
		return default;
	}

	var approxMatch = back.Hotels

		.FirstOrDefault(hotel => -1 != CultureInfo.InvariantCulture.CompareInfo.IndexOf(
			hotel.HotelName,
			hotelName,
			CompareOptions.IgnoreCase | CompareOptions.IgnoreNonSpace | CompareOptions.IgnoreSymbols))

		?.HotelId;

	return approxMatch;
}

Emptyness

T[] array = Array.Empty<T>();

string a = string.Empty;

Denullabilization (var!)

//assume array of nullable
Foo?[] nullableFooArray;

//filter null values and cast to non nullable, aka base type of Nullable<T>
Foo[] fooArray = nullableFooArray
	.Where(nullableFoo => nullableFoo != null)
	.Select(nullableFoo => nullableFoo!) // here ! means : believe me it is non null, indeed I took care to filter at previous statement
	.ToArray();

Path %/\ jungle: normalize it!

//1.Environment.ExpandEnvironmentVariables to resolve environment variables
//2.Path.GetFullPath to normalize path separator characters
var rootDir =
  Path.GetFullPath(Environment.ExpandEnvironmentVariables(Path.Combine(
	  "%ProgramData%", "Vendor", "Product", "subfolder"
  )));