Question

a ?? b

• If a is not null => returns a.
• Else (a is null) => returns b.

I want to simulate something like its inverse (AFAIK there is no operator to do this):

• If a is null => return a.
• Else (a is not null) => returns b.

The idea is that b would be the result of a function that receives a and needs to avoid null parameters. Like this: a XX fn(a) where XX would be the operator (if it exists).

My only two variants are:

• a == null ? a : fn(a)
• a == null ? null : fn(a)

Is there any way to simplify this code?

Answer 1

Not sure exactly what you’re trying to accomplish? Something like this?

TResult NullFn<TParam, TResult>(TParam a, Func<TParam, TResult> method)
{
if(a == null) return null;
return method(a);
}

...

var result = NullFn(a, a => fn(a))

But the best solution IMHO would be to just have fn return null if it is passed a null value.

EDIT:

The method at the top is only an example. You might want to use something like this in a situation where you’ve got a LOT of the same operation over and over again in a specific area and you can’t change fn because it would make is easier to focus on the rest of the code and there’s a chance you might want to alter the null-handling behavior for all your operations at once in the future. (I’m assuming that is the case because you’re asking in the first place.) But I wouldn’t use this across an entire application because it isn’t clear what’s happening if you don’t have the NullFn function right in front of you.