If you read my article on the null coalescing operator (??), you’ve probably got a good idea on how useful it is. It makes your code more declarative, which makes it easier to read. But I find one thing disappointing about it, which I hope can be corrected in C# 5 with the introduction of a new operator.
One way to use the null coalescing operator is by checking a variable against itself, and if it’s null assign another value. Besides eliminating imperative code, this is great when combined with factory methods.
client.WorkOrder = client.WorkOrder ?? WorkOrder.Create();
My complaint is that you have to declare the same value on the left and right side. It’s not much, but it’s easily corrected. Due to C#’s C-based heritage, other types of assignment operators, called compound assignment operators, already exist: +=, –+, *=, /=, %=, &=, |=, ^=, <<=, and >>=. These work as if you had broken them apart. In other words, x += y is the same as x = x + y. There are two differences: the left operand isn’t repeated and the C# compiler evaluates the left operand once with the compound assignment operator.
I propose a new compound operator for C# 5: the null coalescing operator. The symbol for it would logically be ??=. It will simplify our code when working in a declarative manner.
client.WorkOrder ??= WorkOrder.Create();
It doesn’t require a framework change as the IL generated by compound assignment operators is the same as their analogues. It’s a compiler change, and I don’t believe it would be a difficult one at that.
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