Search code examples
delphidllmigration

migrate huge old Delphi application to newest Delphi version

I have an old Delphi application and i want to migrate it to the newest Delphi version. The problem is that the application is huge and migrating whole app at once would be too complex. I wonder what is the best approach to do this... Maybe form by form, placing a form into a dll and then using older forms in the new Delphi app and replacing them one by one (after clients confirm one form is working ok to continue with the next one). Not sure if this would be possible at all...Any other ideas?

Solution

  • Here is my advice. Before you start migrate, do a refactoring of your existing source-base.

    1. Remove un-used stuff.

    2. Try to move as much as possible to standard delphi components.

    3. Remove "un-used" units from your uses-statements.

    4. If needed, try to do some layering (App-UI,App-Logik,DB-Layer,Libraries)

    5. Look for 3rd-Party Components/Libraries, which might be not needed anymore in the latest Delphi Version, because the functionality is now included in Delphi. If you spot such components/libraries, try to encapsulate them.

    Now you have a new version of your software (still in the old delphi). Test it as exact as possible (Unit-Tests would be perfect).

    If this is done, then you start to migrate to newer Delphi. I recommend to do it in one go (instead of .dll and one by one).