You can define a companion object for your data class and overload its invoke operator to use default values when null is passed: data class Data private constructor( val name: String, val number: Long ) { companion object { operator fun invoke( name: String? = null, number: Long? = null ) = Data( name ?: … Read more
I’m just replying to the first part of the question to start with. (I suggest that the second part should be a separate question; it’s more likely to be a bug.) There’s only an explicit conversion from decimal to int, but that conversion is being implicitly called in your code. The conversion happens in this … Read more
The ? symbol after a type is only a shortcut to the Nullable type, bool? is equivalent to Nullable<bool>. bool is a value type, this means that it cannot be null, so the Nullable type basically allows you to wrap value types, and being able to assign null to them. bool? can contain three different … Read more
If you want be sure you need to check both SomeProperty == null || SomeProperty == Guid.Empty Because it can be null ‘Nullable’ and it can be an empty GUID something like this {00000000-0000-0000-0000-000000000000}
There’s plenty of options… decimal? x = … decimal a = (decimal)x; // works; throws if x was null decimal b = x ?? 123M; // works; defaults to 123M if x was null decimal c = x.Value; // works; throws if x was null decimal d = x.GetValueOrDefault(); // works; defaults to 0M if … Read more
EDIT: Important Note As Quentin C pointed out in the below comment, the behavior listed here is only when strict null checking is enabled: “strictNullChecks”: true in tsconfig.json. The types null and undefined are handled as separate types. The optional type is special, also allowing arguments to be left out of function calls. 1. Without … Read more
list?.Count > 0: Here you compare an int? to an int, yielding a bool, since lifted comparison operators return a bool, not a bool?. a?.B: Here, you have a bool?. if, however, requires a bool.
The problem occurs because the conditional operator doesn’t look at how the value is used (assigned in this case) to determine the type of the expression — just the true/false values. In this case, you have a null and an Int32, and the type can not be determined (there are real reasons it can’t just … Read more
In .NET 6, the NullabilityInfoContext APIs were added to handle this. See this answer. Prior to this, you need to read the attributes yourself. This appears to work, at least on the types I’ve tested it with. public static bool IsNullable(PropertyInfo property) => IsNullableHelper(property.PropertyType, property.DeclaringType, property.CustomAttributes); public static bool IsNullable(FieldInfo field) => IsNullableHelper(field.FieldType, field.DeclaringType, field.CustomAttributes); … Read more
You can’t. Struct are considered value types, and by definition can’t be null. The easiest way to make it nullable is to make it a reference type. The answer you need to ask yourself is “Why is this a struct?” and unless you can think of a really solid reason, don’t, and make it a … Read more