How to have multiple type libraries in a Delphi project?

Question

If you have a Delphi project and want to add a type library to it, you can pretty easily.

However, we want to be able to add multiple different type libraries. The Delphi XE IDE seems to force you to have one and only one type library that is named

MyProject.tlb

I'd like to be able to have multiple type libraries in our main project and do COM Plugins, but I don't want one monolithic type library, but rather multiple type libraries for various different types of plugins.

Is this doable? Is it just the IDE that is enforcing the "There can only be one TLB" rule?

Answer 1

AFAIK, the IDE does not support multiple TypeLibraries in a project. What you can do, however, is create separate external TypeLibraries (File > New > Other > Delphi Projects > Active > Type Library) to create standalone .tlb files, register them with the OS, and then reference them in your project's TypeLibrary if needed.

However, if all you are doing is creating COM plugins that your main project consumes, then there is no need to include the COM plugin TypeLibraries in your main project. All you need is the interface definitions. Simply add the generated <UnitName>_TLB.pas units to your main project's uses clauses where needed. Do not add the actual .tlb files themselves to your main project.

Answer 2

You most certainly can. Type libs are just treated as another resource in the final compilation of the binary.

It sounds like your IDE is limiting you to one type lib. If you can edit the raw .RC file you can include a reference to your .tlb there.

E.G... From the TEXTINCLUDE section of the .RC file.

3 TEXTINCLUDE  
BEGIN
    "1 TYPELIB ""junk.tlb""\r\n"
    "\0"
END

4 TEXTINCLUDE  
BEGIN
    "2 TYPELIB ""junk2.tlb""\r\n"
    "\0"
END

The resource compiler should include it as a second TYPELIB resource. I just did this by hand, I didn't use the support Visual Studio provided.

Once I compiled my EXE I opened it up and looked at the resources. There were two type libs.

I hope this helps.