Build ActiveX DLL


I have built serveral actviex dll files, they are called first.dll, second.dll, third.dll.

first.dll will be uesd by both second.dll and third.dll.

I found if I made some code modification at first.dll and rebuitl it.

I also need to rebuilt the second.dll and third.dll.
But the input arguments and output arguments at each method of first.dll remain the same.

Why do I need to rebuild second.dll & third.dll also in order to use the second.dll and third.dll at my executable application?


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corvanderlindenConnect With a Mentor Commented:
The first time you compile your DLL make sure you have 'No Compatibilty' set in The Component Tab. Build this DLL in for example a Compatibility subdirectory of your project. You now have a reference DLL for binary compatibility. As long as you do not change your interface VB will now make sure all your GUID's and IID's will not change.

NOTE : your interface changes when parameters or return values change, and VB will warn you.

Caution : VB will NOT warn you if you for example add a member to a Public ENUM or add a Sub or Function to your interface. But realize that in these cases your interface HAS changed and you can get in trouble (to see what is going on view the DLL's typelib with OLEView)

Then make sure you set Binary Compatibilty in the Component Tab and select your previous build DLL in the Compatability directory. Then build your DLL again in your Bin or project directory (just make sure you do not overwrite your first built). This DLL will be your working DLL.

Does first.dll have its compatibility set for binary compatibility?
When you create an activeX DLL it is assigned to it a special ID (GUID), each time that you compile without binary compitability a new ID is created, for this reason you have to compile again every project that has a reference to your ActiveX DLL.

To avoid this, on the Project menu, click on the project properties and in the "Component tab" choose Binary Compatibility and in the textbox below choose your previous compiled ActiveX DLL.

Note that the first time that you compile your project it option must not be set (you do not have a previous DLL to preserve the compatibility).

hope it Helps
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