Yes, using some minor hackery found in this SO answer “Overload operator in F#”. At compiled time the correct overload for an usage of either (‘a Nullable, ‘a) ->’a or (‘a when ‘a:null, ‘a) -> ‘a for a single operator can be inlined. Even (‘a option, ‘a) -> ‘a can be thrown in for more … Read more
For a simple example of SQLAlchemy’s coalesce function, this may help: Handling null values in a SQLAlchemy query – equivalent of isnull, nullif or coalesce. Here are a couple of key lines of code from that post: from sqlalchemy.sql.functions import coalesce my_config = session.query(Config).order_by(coalesce(Config.last_processed_at, datetime.date.min)).first()
The name of the operator is the null-coalescing operator. The original blog post I linked to that covered the differences in null coalescing between languages has been taken down. A newer comparison between C# and Ruby null coalescing can be found here. In short, you can use ||, as in: a_or_b = (a || b)
I just found this: The ?? operator aka the Null Coalescing Operator You also have it in C/C++ as a GNU extension using the ?: operator : string pageTitle = getTitle() ?: “Default Title”;
For C# 7 In C# 7, throw becomes an expression, so it’s fine to use exactly the code described in the question. For C# 6 and earlier You can’t do that directly in C# 6 and earlier – the second operand of ?? needs to be an expression, not a throw statement. There are a … Read more
There are a couple! The ternary operator: testvar2 = testVar1 != null ? testvar1 : testvar2; Would be exactly the same logic. Or, as commented you can use the null coalescing operator: testVar2 = testVar1 ?? testVar2 (although now that’s been commented as well) Or a third option: Write a method once and use it … Read more
It’s the null coalescing operator. It was introduced in C# 2. The result of the expression a ?? b is a if that’s not null, or b otherwise. b isn’t evaluated unless it’s needed. Two nice things: The overall type of the expression is that of the second operand, which is important when you’re using … Read more
Don’t worry about the performance, it will be negligible. If you are curious about it, write some code to test the performance using Stopwatch and see. I suspect you’ll need to do a few million iterations to start seeing differences though. You can also never assume about the implementation of things, they are liable to … Read more
var nums = new int?[] {1, null, 3}; var total = nums.Sum(); This relies on the IEnumerable<Nullable<Int32>>overload of the Enumerable.Sum Method, which behaves as you would expect. If you have a default-value that is not equal to zero, you can do: var total = nums.Sum(i => i.GetValueOrDefault(myDefaultValue)); or the shorthand: var total = nums.Sum(i => … Read more
Elvis ?: returns the first argument if it contains a “true-ish” value (see which values are considered loosely equal to true in the first line of the Loose comparisons with == table). Or the second argument otherwise $result = $var ?: ‘default’; // is a shorthand for $result = $var ? $var : ‘default’; Null … Read more