VB6 with DLL

[dilettante]

Another thing you should note is that typically registration is done by the ActiveX DLL itself. When you compile an ActiveX DLL in VB6 it actually exports two C style methods, DllRegisterServer and DllUnregisterServer. What actually happens when you call Regsvr32 on ActiveX DLLs is that it calls one of these functions depending on weather you're registering or unregistering it.

Except that:

SelfReg Table

Remarks

Installation package authors are strongly advised against using self registration. Instead they should register modules by authoring one or more tables provided by the installer for this purpose. For more information, see Registry Tables Group. Many of the benefits of having a central installer service are lost with self registration because self-registration routines tend to hide critical configuration information. Reasons for avoiding self registration include:

• Rollback of an installation with self-registered modules cannot be safely done using DllUnregisterServer because there is no way of telling if the self-registered keys are used by another feature or application.
• The ability to use advertisement is reduced if Class or extension server registration is performed within self-registration routines.
• The installer automatically handles HKCR keys in the registry tables for both per-user or per-machine installations. DllRegisterServer routines currently do not support the notion of a per-user HKCR key.
• If multiple users are using a self-registered application on the same computer, each user must install the application the first time they run it. Otherwise the installer cannot easily determine that the proper HKCU registry keys exist.
• The DllRegisterServer can be denied access to network resources such as type libraries if a component is both specified as run-from-source and is listed in the SelfReg table. This can cause the installation of the component to fail to during an administrative installation.
• Self-registering DLLs are more susceptible to coding errors because the new code required for DllRegisterServer is commonly different for each DLL. Instead use the registry tables in the database to take advantage of existing code provided by the installer.
• Self-registering DLLs can sometimes link to auxiliary DLLs that are not present or are the wrong version. In contrast, the installer can register the DLLs using the registry tables with no dependency on the current state of the system.

For these reasons self registration (which is also what running regsvr32.exe does) has been considered very bad form for a long, long time.