Question

Basic question here – I have many lines of code that look something like:

var a = (long_expression == null) ? null : long_expression.Method();

Similar lines repeat a lot in this function. long_expression is different every time. I am trying to find a way to avoid repeating long_expression, but keeping this compact. Something like the opposite of operator ??. For the moment I’m considering just giving in and putting it on multiple lines like:

var temp = long_expression;
var a = (temp == null) ? null : temp.Method();

But I was curious if there is some clever syntax I don’t know about that would make this more concise.

Answer 1

Well, you could use an extension method like this:

public static TResult NullOr<TSource, TResult>(this TSource source,
    Func<TSource, TResult> func) where TSource : class where TResult : class
{
    return source == null ? null : func(source);
}

Then:

var a = some_long_expression.NullOr(x => x.Method());

Or (depending on your version of C#)

var a = some_long_expression.NullOr(Foo.Method);

where Foo is the type of some_long_expression.

I don’t think I would do this though. I’d just use the two line version. It’s simpler and less clever – and while “clever” is fun for Stack Overflow, it’s not usually a good idea for real code.