Delphi – rtl100.bpl was not found

Another disadvantage to BPL's. When you switch Delphi versions you will have to re-distribute new plugins. After many attempts at attempting to find the perfect plugin system, I ended up with COM and I have never regretted that decision. In a commercial application which has had the plugin requirement for over 8 years, the application has continued to move forward and yet some of the plugins that were released with the first iteration still exist in their ORIGINAL form.

If you choose this method, do yourself a favor and start with a simple interface and then add new interfaces upon it. You don't want to ever change your base interface, so keep it simple and sweet.

Your BPL requires the RTL and VCL packages. If your Application doesn't require them, then that means the RTL and VCL units are compiled into your EXE file. When your EXE loads your BPL, you now have two copies of the RTL and VCL units — one set of copies comes from within the EXE, and the second copies come from the RTL and VCL packages that your package implicitly causes to be loaded.

Delphi isn't intended to accommodate that situation. It's possible that you have memory that was allocated by one RTL and attempted to get freed by the other RTL. Or there might be function pointers in the EXE that refer to functions that were in the VCL package.

I see three options for you:

1. Compile your EXE to use packages. Specifically, it should require the same RTL and VCL packages that your BPL requires.

2. Make your BPL not require any other packages. If it doesn't require RTL and VCL, then any RTL and VCL units that your package uses will get compiled into your BPL. You'll end up with two separate copies again, but it should work better since neither copy will think it's supposed to be shared.

3. Load your package like a real DLL instead of like a package. You said you wanted to use it like a DLL, so do that. Use LoadLibrary, and then use GetProcAddress to get whatever functions you want to call. If you go this route, it's probably better to not make your code be a package at all. Make it a DLL, and export functions that only use parameter types that you'd expect to find in other DLLs, like integers, character pointers, and record pointers, not strings or objects.

It should be clear that the first option is the easiest. The second could probably work, and it sounds like that's the way you'd prefer, but I expect it will generate more headaches before it finally works. The third option is best if you'll ever have to use other development environments during the lifetime of this project.