Also, if you could email me, I can go into more detail why I thought an interpreter might actually be a workable solution. It probably sounded ridiculous in the way that I asked the question (obviously building a full VB6 clone would be an almost insurmountable task). But the way the code base I’m dealing with is structured, it may be possible that I could write an interpreter for a very small subset of the language.

Cheers,
Michael

Thank you for the quick reply! Your response pretty much solidifies what I was already thinking: It is a pretty big project to write my own VB6 interpreter. Probably bigger than I want to take on under the circumstances.

If you could email me directly, I can go into more detail, but here is the gist of it: Someone that I used to work for years ago has a REALLY old code base of BASIC code for some educational software. I mean, this code was UPGRADED to VB6, and that was a bit of a project! That’s how old it is. As a favor to him, I was going to go through some possible ways to move the code base to a more modern platform. Although writing my own interpreter is a very big project, converting the code by hand is daunting also. There are thousands of individual BASIC files on which I would have to do manual conversion (even if I used one of the migration tools – VB6 to VB.NET – that are out there).

Oddly enough, one of the more interesting and potentially promising ideas I found was an obscure program called Jabaco. It converts VB6 code into a platform where it can run on Java. I was very skeptical, but on a first run-through, it did a surprisingly decent job with this old BASIC code. It supports GOTO , for example, which this code is littered with. I contacted the guys maintaining Jabaco, and if I can get a version that implements GOSUB/RETURN as well, I actually think it might work for me. (You can probably tell from just this little bit – GOTOs, GOSUB/RETURNs – that this code I’m talking about upgrading is pretty nasty).

I will look into the projects you mentioned. I’m sure there are some valuable things for me to learn from those projects, even though they are primarily VB.NET. Because of the nature of this particular code base with which I’m dealing, I’m going to also look at FreeBASIC and any other old-school BASIC compilers or interpreters I can find.

Just to summarize my “dream scenario” and why I was thinking about writing my own BASIC interpreter: If I could write my own interpreter and host it within a web page, for instance, then I could help my old employer run his apps from within a browser – which would mean they would work on almost any device. Right now, the apps are pretty much Windows only.

Thanks again for your time, Gary.

Cheers,
Michael

I’ve got a brief post on making a BASIC interpreter here: http://marovada.com/2012/09/03/how-to-make-a-basic-compiler-or-interpreter/ I’m not sure if you were able to find it.

It will be very challenging to write a VB6 compiler/interpreter from scratch and that’s probably an understatement! My BASIC interpreter is not nearly as sophisticated as VB6 (not even close) and it’s taken me a few years to put it together (albeit in my spare time). There’s an open source VB.Net compiler here: http://sourceforge.net/projects/vbnc/ It’s not VB6 and it’s written in VB.NET but it could give you an understanding of how it all works. It’s also pretty old. I think it’s been overtaken by Mono which has Visual Basic compatibility built in.

Why do you want to create a VB6 compiler/interpreter? If you don’t want to answer in a comment then just reply that you’d prefer me to email.

Gary