HOWTO: Use the Procedure Attributes Dialog Box

• Control Creation and Enterprise Editions of Microsoft Visual Basic, for Windows, version 5.0

SUMMARY

Just as there are properties associated with objects, there are also type library attributes for each object property, method, and event. The Tools|Procedure Attributes menu in Visual Basic 5.0 allows you to set and alter these attributes. The Procedure Attributes dialog box is disabled unless you have existing property procedures, methods, or events in your project and you are currently in a project file (for example, Form, UserControl, Basic Module, etc.). Once you add a property procedure, method, or event to your project file you can set specific attributes for it.

MORE INFORMATION

The Procedure Attributes dialog box contains the following attributes:

1. Name: Lists of all available properties, methods, and events. The list box defaults to display properties for the property procedure, method, or event that the cursor was on in the code window. You can select and modify a different property procedure, method, or event without having to leave the dialog box.

2. Description: Enter information that you want to display in the description area of the Object Browser.

3. Project Help File: Displays the path to the Help file that is specified in the General tab of the Project Properties dialog box. This option is read-only.

4. Help Context ID: Allows you to specify a Help Context ID to be associated with the selected property procedure, method, or event. If you are in Code View or in the Object Browser, you can get help on this procedure, method, or event based on this ID.

1. Procedure ID: Sets a standard member ID for the currently selected property, event or method. This member ID may be one a client may know about, and therefore behaves in an expected way.

   A ProcedureID is a GUID. If this is left blank, Visual Basic 5.0 will assign one. There are some common GUIDs that developers can use for their procedures that the host application may be aware of and handle in a specific manner. By choosing a common GUID, you are letting the host application know that your code behaves in a standard fashion. For example, if you have a procedure to handle the background color, you could use the predefined GUID for BackColor because it’s a common property that controls expose. The host application can look for this GUID and, if it is found, can assume that your code will behave in a predictable fashion.

   Setting this attribute does not guarantee that the procedure will behave as expected. It is up to you to write code to do what you say you’re going to do. For example, if you select the Refresh Procedure ID, the code you write and associate with the procedure should Refresh the control.

   NOTE: Assigning a property procedure or method a Procedure ID of 0 makes it the default property (also known as the Value property).

2. Use This Page In Property Browser: This setting is only available for Properties. It sets which property page is used for your property when you change its value in the Property Window. You can select a predefined property page or one of your own custom property pages. If you select a predefined property page, make sure your property exposes the appropriate data type (OLE_COLOR, FONT, PICTURE).

   If you want the Properties Verb to appear when you right-click your control, you need to add the PropertyPage to the UserControl’s PropertyPages property. When you select modify PropertyPages, you can choose which property pages appear when you select the Properties Verb for your UserControl. You can also use this dialog box to modify the order in which the pages are presented.

3. Property Category: This setting is only available for Properties. It lets you select which category your property appears in under the Property Window's "Categorized Tab."

4. Hide This Member: Prevents your procedure from appearing in the Object Browser (unless the Object Browser has "Show Hidden Members" enabled).

5. User Interface Default: You can select this for one Event and one Property per UserControl. This determines which event is displayed when you double-click on a new instance of the control to see the Code Window. This determines which property is automatically highlighted in the Property Window. Note that this is not the same as the default property, which applies to coding (see Procedure ID above).

6. Don’t Show In Property Browser: This setting is for properties only. This option prevents your property from appearing in the Property Window. However, it still appears in the Object Browser.

1. Property is data bound: Determines if the property supports databinding and appears in the DataBindings Collection.

2. This Property binds to DataField: Determines if the field that this property is bound to is specified in the DataField property. When this is set the user can set the DataField property instead of using the DataBindings Collection.

3. Show in DataBindings Collection at design time: Determines if the property will appear as bindable at design time. If this is set, the property appears in the Bindings dialog box. If it is not selected, the property does not appear in the user interface as bindable property but you can continue to write code to access it.

4. Property will call CanPropertyChange before Changing: Tells the control container that the control will always call the CanPropertyChange method and respect the return value before changing a property value.

REFERENCES