CA1062: ValidateArgumentsOfPublicMethods on co-constructor calls

Question

I have a class with two constructors that look like this:

public MyClass(SomeOtherClass source) : this(source, source.Name) { }
public MyClass(SomeOtherClass source, string name) { /* ... */ }

When I run FxCop, it correctly reports a violation of CA1062: ValidateArgumentsOfPublicMethods, because if source is null in the first constructor, it will throw a NullReferenceException on source.Name.

Is there any way to fix this warning?

I could make an extension method that checks for null and returns its argument, but it would be ugly. Also, as I understand, it wouldn't resolve the warning because FxCop wouldn't realize what it does.

Answer 1

Like this?

public MyClass(SomeOtherClass source) : this(source, source == null ? null : source.Name) { }
public MyClass(SomeOtherClass source, string name) { /* ... */ }

Answer 2

There are legitimate times to turn off FxCop warnings and this could very well be one, but you can correct the problem by either a ternary expression that checks for null and throws an exception (or substitutes a default value), or a call to a static method that checks for null and throws the appropriate exception.

Answer 3

Since this question was asked some time ago I just want to note with the later features in C# you can now also use this:

public MyClass(SomeOtherClass source) : this(source, source?.Name) { }

Answer 4

I would say the only way to fix this warning would be to turn it off. FxCop is a great tool but sometimes you need to remember that it is just a tool and can make suggestions that are not always fitting to your code.

In this example I would say ignore the warning or disable it if you don't want to see it.