the order of the parameters, the name of the property or method, or the data type of the return value. When you create the executable for a version-identical upgrade, you can use the same file name for the executable. Visual Basic uses the same version number for the type library. Important When you release a new version of your component with a version-identical or version-compatible interface, and retain the same file name for the executable, you should always use the Make tab of the Project Properties dialog box to increment the file version number. This ensures that the setup programs for applications that use your component will replace old versions during setup. Version-Compatible Interfaces When you enhance your component by adding new classes, or new properties and methods to existing classes, you can continue to use the same name for your executable. As long as you make no changes to existing properties and methods, Visual Basic updates the version number of the type library but keeps it compatible with the old version number. Client applications that are built using the new version of your component will compile with the new version number, and can make use of all the new features. They cannot be used with earlier versions of your component, however, because type library versions are only upward-compatible. As with version-identical releases, remember to increment the file version number of the executable. Version-Incompatible Interfaces Sometimes design decisions made in an earlier version of a component fail to anticipate future needs. If you want the code in the component to be useful in new development projects, you have to change the interface. For example, the CupsPerAnnum parameter of the Coffee method might be implemented as an Integer in the first version of a component. It may become apparent, after the component has been in use for some time, that some clients need to pass a larger value than can be contained in an Integer. Changing the declaration of a method is only one of several actions that will cause Visual Basic to make the version number of the type library incompatible, rendering the new version unusable with client applications compiled with earlier versions. The following changes will cause a version incompatibility: · Changing the Project Name field on the General tab of the Project Properties dialog box. · Changing the Name property of any class module whose Public property is True (controls), or whose Instancing property is not Private (class modules). · Deleting a public class module, or setting its Instancing property to Private. · Deleting a public variable, procedure, or Property procedure from a public class module or control, or changing it to Private or Friend. · Changing the name or data type of a public variable, Next topic Previous topic |
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