Question

When creating a named argument for a constructor, I am running into a problem where the only constructors avaliable to me ask for a refOrOutKeyword SyntaxToken. Passing null is not allowed, moreover Syntax.ParseToken("") fails. Syntax.Token(SyntaxKind.RefKeyword) and Syntax.Token(SyntaxKind.OutKeyword) are both unsuitable, as they insert either ref or out:

var ctorArgs = Syntax.ArgumentList();
var ctor = enclosingType.Members
                        .OfType<ConstructorDeclarationSyntax>()
                        .OrderBy(cc => cc.ParameterList.Parameters.Count)
                        .FirstOrDefault();
if (ctor != null)
{
    //
    // Summary:
    //     Creates a new ArgumentSyntax instance.
    // public static ArgumentSyntax Argument(
    //     NameColonSyntax nameColon,
    //     SyntaxToken refOrOutKeyword,
    // ExpressionSyntax expression);
    ctorArgs.AddArguments((
        from param in ctor.ParameterList.Parameters
        select Syntax.Argument(
                Syntax.NameColon(param.Identifier.ValueText),
                Syntax.ParseToken("") /* <- what to put here */, 
                Syntax.DefaultExpression(param.Type))
    ).ToArray());
}

I’ve not found any suitable documentation to elucidate how I can create named arguments either.

Answer 1

Usually, looking how is such code represented at runtime helps. If I parse code that uses named arguments and look at RefOrOutKeyword.Kind of the ArgumentSyntax in question, it’s None. So, you need to do the same thing: create a SyntaxToken with None as its Kind:

Syntax.Token(SyntaxKind.None)