Question

I had a discussion today about refactoring this (#1)

public void MyFunc(object myArgument)
{
    if(myArgument == null)
        throw new ArgumentNullException("myArgument");
....

With this (#2)

//inside a shared assembly in a class called Guard
public static void AgainstArgumentNull(object obj, string message)
{
    if (obj == null)
        throw new ArgumentNullException(message);
}

public void MyFunc(object myArgument)
{
    Guard.AgainstArgumentNull(myArgument, "myArgument");
....

My intuition was that #1 was better for the following reasons:

1. #1 is simpler than #2 in the sense that it requires no knowledge of Util library, just basic c# knowledge
2. #1 will not remove the resharper ability to rename the string passed to ArgumentNullException constructor.
3. #2 will increase the dependencies for the code (must have access to the dll containing the dll)
4. The stacktrace will not be the same for #2 as it would be for #1

My questions here are:
Is my intuition correct?
Could the fact that we are throwing the exception from another assembly not become trouble in some scenarios?

Answer 1

For this particular case, you shouldn’t be using Guard anyway. You should be using Code Contracts.

Contract.Requires(myArgument != null);