The Run-Time Object

ActiveX designers may have different visual designers and run-time objects for the following reasons:

• The visual designer and the run-time object will differ in implementation. For example, the design-time object must be visible, but the run-time object may be invisible.
  
  
• The application requires a different visual interface at run time because of size or ease of implementation.
  
  
• The visual designer has dependencies that the run-time object does not have. In this case, creating separate objects can simplify distribution.
  
  
• Licensing requirements are different at design time and at run time.
  
  
• The run-time object is public and can be created by other applications. In this case, interface implementations might differ. For example, the host might provide a different client site at run time and at design time.

If the run-time object differs from the design-time object, the ActiveX designer must support a class factory that can create instances of the run-time object, and the designer must describe the run-time object's types and visual representation. Hosts such as Visual Basic use this information when creating an executable file.

If the run-time object and the design-time object are the same, the ActiveX designer uses the same type information and class factory at both design time and run time.

For example, ActiveX designers that define forms or forms packages often require the same type information at design time and at run time. Their design-time and run-time objects usually are the same.

Other kinds of ActiveX designers might have different requirements for type information or user interfaces, and therefore would have to implement separate design-time and run-time objects. An ActiveX designer that allows its users to devise queries to remote databases, for example, may not need a user interface at run time. Conversely, an ActiveX designer used for creating multimedia objects is likely to need different type information at run time.

The design-time and run-time objects can be distributed in the same DLL or in different ones.

ActiveX designers differ from add-in tools that are typically installed into an integrated development environment. ActiveX designers generate programmable objects that can be instantiated at run time. An add-in such as a source code control system would not be implemented as an ActiveX designer because it has no run-time component.