Legible or not: C# multiple ternary operators + Throw if unmatched [closed]

Answer 1

I like the conditional operator, and use it a lot.

This example is a little confusing, because the nature of the operator is not clear from the layout and usage.

At the very least I like to make the choice and alternatives clear by using this formatting:

choice
  ? true-case
  : false-case

But if we apply that to your code it reveals the lack of clarity in using the construct this way:

return
    this.Script == null 
                ? false 
                : parameter == "Step" 
                    ? true
                    : parameter == "Element" 
                        ? this.ElementSelectedInLibrary != null && this.SelectedStep != null
                        : parameter == "Choice" 
                            ? this.SelectedElement != null
                            : parameter == "Jump" 
                                ? this.SelectedStep != null
                                : parameter == "Conditional jump" 
                                        ? false
                                        : false.Throw("Unknown Add parameter {0} in XAML.".F(parameter));

This feels to me like we're trying to use the conditional operator like a switch statement, where a switch statement, or better yet a design pattern like the Command Pattern would be much clearer.

Answer 2

Why not use a nullable type bool?

private bool? CanExecuteAdd(string parameter) {
return
    this.Script == null ? false
    : parameter == "Step" ? true
    : parameter == "Element" ? this.ElementSelectedInLibrary != null && this.SelectedStep != null
    : parameter == "Choice" ? this.SelectedElement != null
    : parameter == "Jump" ? this.SelectedStep != null
    : parameter == "Conditional jump" ? false
    : null;

}

Answer 3

It looks fine to me, but I'd alter your Throw method to:

static TObject Throw<TObject, TException>(this TObject ignored, TException exception)
{
   throw exception;
}

That allows you to specify the kind of Exception thrown.

Answer 4

Being non-idiomatic means that you're forcing the reader to spend time thinking about whether or not what they're reading means what they think it means.

So being legible doesn't buy the sophisticated (namely, suspicious) reader very much. This strikes me as a case of being clever for the sake of being clever.

Is there any reason not to use a switch or an else if construct here?

Answer 5

Too hard to read, take care of exceptions first.

Handle each case in it's own if, then you can have more complex conditions.

This is one of the few times, this many separate returns in a method would be acceptable

private bool CanExecuteAdd(string parameter) 
{       
    if (this.Script == null)
        return false;

    if (parameter.NotIn([] {"Step", "Element", "Choice", "Jump", "Conditional jump"})
        throw new Exception("Unknown Add parameter {0} in XAML.".F(parameter));

    if (parameter == "Step") 
        return true;

    if (parameter == "Element")
        this.ElementSelectedInLibrary != null && this.SelectedStep != null;

        // etc, etc
}

Oh, and the .NotIn is an extension method, the opposite of this, I would imagine (can't say this is quite exact to what is needed)

public static bool In<T>(this T obj, IEnumerable<T> arr)
{
    return arr.Contains(obj);
}

Answer 6

I vote for non-legible.

Although the syntax is correct, it's somewhat convoluted and since it's not, dare I say, "traditional", many developers will have to waste time trying to ensure they understand what they're reading. Not an ideal situation.

Readability is definitely one key ingredient to good coding, and I would say your sample isn't immediately readable for most devs.