Public Shared Narrowing Operator CType ( _
    attribute As XAttribute _
) As String

Dim input As XAttribute
Dim output As String

output = CType(input, String)

public static explicit operator string (
    XAttribute attribute
)

static explicit operator String^ (
    XAttribute^ attribute
)

JScript does not support the declaration of new casting operators.

XElement root = new XElement("Root",
    new XAttribute("Att", "attribute content")
);
XAttribute att = root.Attribute("Att");
string str = (string)att;
Console.WriteLine("(string)att={0}", str);

Dim root As XElement = <Root Att="attribute content"/>
Dim att As XAttribute = root.Attribute("Att")
Dim str As String = CStr(att)
Console.WriteLine("(string)att={0}", str)