MORE ABOUT CLASSES in visual C#

Creation Data Matrix 2d barcode in visual C# MORE ABOUT CLASSES

am about to do in Figure 2-72.

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class __declspec(dllexport) NativeClass { private: int m_member;

The GridView control now supports persisted selection (see previous example) and offers the ability to style header columns when they are sorted and contains improved support for working with ViewState disabled.

Fields and methods are the most important of the class member types. Fields are data members and methods are function members.

Think of the first in/first out pattern as the BizTalk car wash. When you take your ride down to the local automated wash-and-dry, the cars are washed in the order in which they roll into the machine. Provided a catastrophic failure of equipment does not occur, if you re the first guy in, you ll be the first guy out. You could certainly throw the car in reverse and delay the process, but if there is someone in line behind you, I can almost guarantee that you ll still be the first guy out, most likely by force. The same applies to BizTalk first in/first out messaging (also known as FIFO). Messages are dealt with as they arrived and delivered in the appropriate order, as shown in Figure 5-9. This is not a default pattern with BizTalk. To get this kind of functionality, you need to configure for it.

Sometimes, you have a code block that must be executed both after error-free execution and in an error situation. An example of this would be freeing a hardware component s resources for use later on or in other parts of a program. You accomplish this with the finally block: try { //using resources } catch { //handling exceptions } finally { //freeing resources } Even if you exit a method with the return keyword within a try block, the code in the finally block is executed before leaving the method. You should protect the code in a finally block (e.g. freeing resources) with a try-catch construct if the code may throw exceptions too.

catch (MyException^ e) { Console::WriteLine("MyException occurred! " + e->Message); } // You may also catch other exceptions with multiple try blocks, // although it's better. catch (Exception^ exception) { Console::WriteLine("Unknown exception!"); } } The output of Listing 10-3 (with no command-line arguments) is shown here:

The IExtenderProvider interface defines just one method: CanExtend(). This method is called by Windows Forms to ask the extender control whether it wishes to extend any given control. Windows Forms automatically calls CanExtend() for every control on the form: Public Function CanExtend( _ ByVal extendee As Object) As Boolean _ Implements IExtenderProvider.CanExtend If IsPropertyImplemented(extendee, "ReadOnly") OrElse _ IsPropertyImplemented(extendee, "Enabled") Then Return True Else Return False End If End Function The ReadWriteAuthorization control can extend any control that implements either a ReadOnly or an Enabled property. This covers most controls, making ReadWriteAuthorization broadly useful. If the potential target control implements either of these properties, a True result is returned to indicate that the control will be extended. The IsPropertyImplemented() method is a helper that uses reflection to check for the existence of the specified properties on the target control: Private Shared Function IsPropertyImplemented(ByVal obj As Object, _ ByVal propertyName As String) As Boolean If obj.GetType.GetProperty(propertyName, _ BindingFlags.FlattenHierarchy Or _ BindingFlags.Instance Or _ BindingFlags.Public) IsNot Nothing Then Return True Else Return False End If End Function