与变量本身的空合并运算符

Question

Is there any way of reduce the null coalescing operator expression when the variable we check is the one we will assign if it's not null?

Example:

DateTime? date1 = DateTime.Parse("11/05/1990");
DateTime? date2 = DateTime.Now;
date1 = date1 ?? date2;

For instance, something like that:

date1 = ?? date2;

I know that's not a big deal but I'm curious.

Answer 1

No, this does not exist in C#.

You can find the list of operators in https://msdn.microsoft.com/nl-nl/library/6a71f45d.aspx .

But isn't date1 = date1 ?? date2 date1 = date1 ?? date2 short enough already ?

Answer 2

No. If there was then:

_field ?? (_field = CalculateFieldValue());

wouldn't be so common in memoised properties.

Answer 3

Starting from C# 8.0 , the null-coalescing assignment operator, ??= , is available.

So it would be

date1 ??= date2;