Writing new guards with extensions in C# 14

[giscus[bot]]

Writing new guards with extensions in C# 14

In C# we have many nice guards sitting on top of static exceptions classes like ArgumentNullException, ArgumentOutOfRangeException, etc: As ArgumentException.ThrowIfNullOrEmpty, ArgumentException.ThrowIfNullOrWhiteSpace. Now we can extend them easily!

https://steven-giesel.com/blogPost/e2552b7a-293a-4f46-892f-95a0cd677e4d?utm_source=paulo+morgado&utm_medium=linkedin

[ignatandrei]

How this is different from

public static void ThrowIfHasOneCharacter(this ArgumentException ex , string argument, [CallerArgumentExpression("argument")] string? paramName = null)
{
    if (argument.Length == 1)
    {
        throw new ArgumentException($"Argument '{paramName}' has exactly one character but shouldn't have.", paramName);
    }
}

?

[linkdotnet]

To make your version work, you need an instance of ArgumentException. You can't call the extension on the type: ArgumentException.Throw.... So you would need to do something like:

var ex = new ArgumentException();
ex.ThrowIfHasOneCharacter(...);

That is not ideal and convolutes the meaning of the code.

[jakenuts]

The new extension capabilities seem great but haven't used them yet, can they be enabled in 9.0 with langversion?

As a matter of taste though, I much prefer a single API for guards like CommunityToolkit.Diagnostics.Guard as I can start typing Guard and then see all the available options pop-up. Having to write out the full exception name, then the method and argument are a bridge to narrow & far.

Possibly even better (depending on taste) would be arg.NotNull() which I use a lot to remove nullable warnings inline. Follows a very easy neural pathway from "I need to make sure" arg "is" NotNull() as opposed to "what is the name of that exception? Oh yeah, then which method? Ok now type the argument".

[linkdotnet]

can they be enabled in 9.0 with langversion?

Yes (tried it out with my code sample). Given that it is lowered almost to the same thing as the "old" extensions, that isn't a big surprise (but a welcome one nevertheless).