Honestly, I’ve always thought NOT NULL should be the default. NULL is the odd special case, and you should make a case for it whenever you use it. Plus it’s much easier to change a column from NOT NULL to nullable than it is to go the other way.
Explanation Although I can’t reproduce this on AbstractItemCountingItemStreamItemReader from this artifact implementation group: ‘org.springframework.batch’, name: ‘spring-batch-core’, version: ‘4.1.2.RELEASE’ , this annotation means that the parent method has some @NotNull / @NonNull annotation on the parameter, while the overriding method has no. To fix it, you need to put the same annotation on the overriding method. … Read more
The ADO.NET API has some problems when it comes to handling nullable value types (i.e. it simply doesn’t work correctly). We’ve had no end of issues with it, and so have arrived at the conclusion that it’s best to manually set the value to null, e.g. myNewRow.myGuidColumn = myGuid == null ? (object)DBNull.Value : myGuid.Value … Read more
You can define private string1: string | undefined;
The relevant section of the C# 3.0 spec is 7.13, the conditional operator: The second and third operands of the ?: operator control the type of the conditional expression. Let X and Y be the types of the second and third operands. Then, If X and Y are the same type, then this is the … Read more
Probably because String?.plus(Any?) is the only plus function which accepts a nullable type as a receiver in Kotlin library. Therefore, when you call null + null, the compiler will treat the first null as String?. If you define an extension function where the receiver type is Int? and the return type is Int, then x … Read more
You can use Nullable.GetUnderlyingType: var t = typeof(T); // … if (Nullable.GetUnderlyingType(t) != null) { // T is a Nullable<> }
Could anyone explain to me why the parenthesis are needed? Because Identity() returns a Foo (not a Foo?) and thus has no Value property. If foo is null, the null will propagate through the Identity call. When you put parentheses around it, the results of the expression is a Nullable<Foo> which does have a Value … Read more
Well yes. The default value of a nullable or other reference type is null while the default value for a long or other value type is 0 (and any other members set to their defaults). In this case: default(Nullable<long>) == null default(long?) == null default(long) == 0L
You could look into Boost.Optional: struct Person { std::string Name; DateTime Birth; boost::optional<DateTime> Death; //… }; Your Death is “uninitialised” at first. You can then assign a value to it with =, like Death = myDateTime. When Death.is_initialized(), you can use Death.get(). Uninitialise it again with Death.reset(). For simple cases like this, though, it’s usually … Read more