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A non-repetitive way to say: access this object if the object is not null

Let's say I have a set of cars where each car has a steering wheel. I would like to write a line of code that looks for a car in the kit and returns its steering wheel, or returns null if the car is not in the kit. Something like that:

Car found = // either a Car or null
SteeringWheel wheel = (found == null ? null : found.steeringwheel);

Is there a way to do this without using found

and null

twice in the expression? I don't like the smell of repetition here.

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3 answers


There is no obvious improvement until C # 6 arrives, but until then, you can hide the nuisance in the extension method.

void Main() {
    Car found = null;// either a Car or null
    SteeringWheel wheel = found.MaybeGetWheel();
}

public static class CarExtensions {
    internal static SteeringWheel MaybeGetWheel(this Car @this) {
        return @this != null ? @this.steeringwheel : null;
    }
}


Some say you shouldn't let extension methods be called null

, but it works. This is a style preference, not a technical limitation.

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You can wait for C # 6.0, and then use a null-conditional operator (aka safe navigation), ?.

:



SteeringWheel wheel = FindCar()?.steeringwheel;
+7


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With linq, you can do

var steeringwheel = cars.Where(c => c.name = "foo")
                        .Select(c => c.steeringwheel)
                        .SingleOrDefault();
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