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Enumerated types are supported in C++/CLI using the enum class (or enum structure). Enum classes have a series of static named fields that have a fixed integral value. There is no operative difference between an enum structure and class. You saw in 2 that the enum class is used to define an enumerated type. Enumerated types are value types. The enum variable may be a handle, in which case it s a boxed value type, or it may be created on the stack. It could also be a member of a class and be part of the layout of the enclosing class. The example in Listing 5-36 shows the basic syntax for declaring and using an enum class. Listing 5-36. Using an Enum // enum.cpp enum class Flavor { Vanilla, Chocolate, Strawberry }; int main() { // The enum variable may be a handle // or a stack variable. If used as a handle, // it's a boxed value type. // The enum value, Vanilla, is // scoped by the enum class name. Flavor^ flavor_handle = Flavor::Vanilla; Flavor flavor_stack = Flavor::Vanilla; } Note the differences between the usage of enum class values and classic C++ enum values. Enum class values are scoped with the name of the enum class; classic C++ enum values are not scoped with the name of the enum.

You can also create an instance of a struct without using the new operator. If you do this, however, there are several restrictions you cannot Use the value of a data member until you have explicitly set it Call any function member until all the data members have been assigned For example, the following code shows two instances of struct Simple created without using the new operator. When there is an attempt to access s1 without explicitly setting the data member values, the compiler produces an error message. There are no problems reading from s2 after assigning values to its members. struct Simple { public int x; public int y; } class Program { static void Main() { No constructor calls Simple s1, s2; Console.WriteLine("{0},{1}", s1.x, s1.y); Not yet assigned s2.x = 5; s2.y = 10; Console.WriteLine("{0},{1}", s2.x, s2.y); } }

By making the application trusted, we can have access to special features (in out-of-browser mode) such as Silverlight OOB window manipulation, cross-domain network access without policy file check, getting a full file path from the Open/Save file dialog, access to user folders, like Documents and Pictures, and COM Interoperability. We will learn these features as we go through this chapter.

Writing applications that make use of multiple threads is a complicated undertaking because when you use multiple threads, multiple things are happening at the same time. The best way to understand this complexity is to think of pairs figure skating.

The MarkDeleted() method is called from the Delete() and DeleteChild() methods. The Delete() method is used to mark a non-child object for deferred deletion, while DeleteChild() is called by a parent object (such as a collection) to mark the child object for deferred deletion: Public Sub Delete() If Me.IsChild Then Throw New NotSupportedException(My.Resources.ChildDeleteException) End If MarkDeleted() End Sub Friend Sub DeleteChild() If Not Me.IsChild Then Throw New NotSupportedException(My.Resources.NoDeleteRootException) End If MarkDeleted() End Sub Both methods do the same thing: call MarkDeleted(). But Delete() is scoped as Public and can be called only if the object is not a child object (a topic covered in the discussion about parent and

Figure 6-20. Class split using partial types All the partial class declarations comprising a class must be compiled together. A class using partial class declarations has the same meaning as if all the class members were declared within a single class declaration body. Besides classes, you can also create partial types for structures and interfaces, which are types I will cover in s 12 and 17, respectively.

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