如何在Swift中声明一个类级别的功能？(How do I declare a class level function in Swift?)

 当将动态传递给CreateCommand ，编译器将其返回类型视为必须在运行时解析的动态。 不幸的是，你在这个解析器和C＃语言之间碰到一些怪异的东西。 幸运的是，通过删除使用var强制编译器执行所期望的操作很容易解决： 
 
public static dynamic DynamicWeirdness() {
    dynamic ex = new ExpandoObject ();
    ex.Query = "SELECT * FROM Products";
    using (var conn = OpenConnection()) {
        DbCommand cmd = CreateCommand(ex); // <-- DON'T USE VAR
        cmd.Connection = conn;
    }
    Console.WriteLine("It worked!");
    Console.Read();
    return null;
}
 
 这已经在Mono 2.10.5上进行了测试，但我确信它与MS一起使用。 

When you pass the dynamic to CreateCommand, the compiler is treating its return type as a dynamic that it has to resolve at runtime. Unfortunately, you're hitting some oddities between that resolver and the C# language. Fortunately, it's easy to work around by removing your use of var forcing the compiler to do what you expect:
 
public static dynamic DynamicWeirdness() {
    dynamic ex = new ExpandoObject ();
    ex.Query = "SELECT * FROM Products";
    using (var conn = OpenConnection()) {
        DbCommand cmd = CreateCommand(ex); // <-- DON'T USE VAR
        cmd.Connection = conn;
    }
    Console.WriteLine("It worked!");
    Console.Read();
    return null;
}
 
This has been tested on Mono 2.10.5, but I'm sure it works with MS too.