I've been asked to re-open a project I wrote in 1998/99 in Delphi 3 and which has been running stably since then. I have the Delphi 3 code base on an aging Windows 98 machine which exists only to keep this project alive. Obviously, I'd like to bring the source code base into the 21st century before undertaking any major revisions.
I note happily that Delphi 2010 (I'm currently on 2007) claims to be able to import projects from Delphi 2 on. Does anyone have any experience importing large projects from Delphi 3? Can I expect this to be an easy transition, or a difficult one?
In addition the original project makes use of third party components including DBISAM, WPTools, and TMS Planner. I note that all of these are still available for the latest release of Delphi. Assuming I first install the new versions into Delphi 2010 can I expect the parts of my application that use these components to be translated as well? I know that at least WPTools has changed some of its component structures and interfaces since the version used in the original application and obviously I'll have some recoding to do there, but will the failure of those parts of the program prevent my code base from being upgraded at all?
Best Answer
It should be very possible to do this migration, and depending on how your code is written, it may either be painful or painless. Unfortunately its not easy to say which until you start the migration process.
The first thing i would do would be to make sure that ALL DFM files are converted to their text representation. This I believe was set to default in later versions of Delphi but as I recall Delphi 3 used a binary format. There should be a utility file named DFMConvert or something in the delphi 3 bin directory which allows you to convert a DFM to text. The reason you will want to do this is to insure that you can read the source if you have to perform a hand edit of the DFM due to a component not loading. Not only are you jumping versions of Delphi, but you also are jumping versions of EVERY component you use and there may be a few incompatibilities that may cause a component to fail loading. I have found if this is the case and you have a "new" version, then use the edit the DFM source directly and compare a test form with the component on it against what your old version contains. Remove anything (or rename) that is out of place and then attempt to load the form again.
As Frabricio mentioned, if you use variants then you will need to make minor adjustments to your uses clause.
The good news is that your code itself should work fine once you get the components/uses clause corrected. If you go directly to Delphi 2010, your only other issue would be Unicode and the compiler does a fantastic job of pointing all of them out to you via errors and warnings.