Tod means Fox

Yesterday was the last day of the conference, and I’m sorry it’s ended. I learned a lot and met a lot of great Fox developers (who are people too, by the way). As the sessions were winding down, many of us hung out outside the conference rooms chatting about all things Fox (and a little about cars). I spoke for a second time today (materials here), and was able to catch a few other sessions. Here are some of my notes:

GDIPlusX library

Bo spoke on the GDIPlusX Library. After a brief overview and some instructions on how to download and get the System object in memory, he took a moment to discuss how system.prg works. What a great piece of architecture. If you haven’t checked out the GDIPlusX Library, you should at least download it and review the system.prg file (and then all the others too). GDIPlusX looks a lot like the .NET implementation on purpose, and works the same too.

Of course, at the moment, my head is spinning on all the other implementations for this type of architecture (Math, IO, etc.).

Now here’s a great tip. Declared DLLs take precedent over function calls. Therefore, if you name your own function the same name as a declared library, your code won’t run — the library’s code will. Bo showed us how he and his team developed a technique to take advantage of this behavior. When you need a dll function, call a VFP function with the same name that DECLAREs the DLL and then calls it (passing in all relevant parameters). Now the DLL function is in memory, and next time you need it, it will use it instead of the function. This means that you only need to declare your DLLs when needed. It also means that CLEAR DLLS ALL commands won’t kill your app if you need a DLL after that call (by the way, this is something I lost sleep over a while ago when some 3rd party function issued this command). Additionally, you now only DECLARE the DLLs when needed. I think Bo mentioned that this technique was first used by Rick Strahl, but on a smaller scale.

Bo also talked about how the GDIPlusX help is coming along. It looks like we’ll have more help for this library than we’ll ever need. Bo and his team are doing an amazing job with it.

A great resource for GDIPlusX, other than the official CodePlex/VFPX site, is Cesar Chalom’s Blog. Cesar has a lot of examples and is very active on the project.

How to OGLE Your Application

Alen Stevens taught us about OGLE: “Optimized, Generic, Layer, Extensions”. The goals of OGLE apps is to be future proof, data source agnostic, location independent, and .NET accessible. OGLE relies on physical n-Tier development techniques, where XML is passed among layers. Using XML in this way helps applications to be future proof. After the session, I talked with Alan about the architecture and he reiterated the importance of using XML to pass data between layers. We’re also reminded that VFP is a state-of-the-art XML parser — faster and more reliable than other available technologies. Therefore, using XML to pass data back and forth is a natural fit for OGLE.

The presentation was a perfect compliment to the whitepaper Alan created. The slides helped shape out the logic in the paper. Now I’ve got my head around it. He walked through lots of code examples, demonstrating the basics of the architecture. I haven’t used com as a middle tier before, so I was glued to this session. I felt that Alan gave a great overview of the process and now I feel like I’m up to speed. He showed us how to set up COMATTRIB attribues, which specifies type library attributes and values for PEMs. This applies to OLEPUBLIC classes only. You can do things like insert descriptions and read-only attributes. These are exposed and can be read by other technologies.

OGLEing apps seem like a smart design move. The separation and isolation of layers in each tier are more dramatic and defined. Although I missed Alan’s test-driven-development (TDD) session, I got the feeling that OGLE is also quite friendly for TDD as well. Whether using FoxUnit (Alan loves this thing) or if you’re just writing stubs to test apps, the architecture makes it simple.

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I’ll be sure to recap the entire event after my wife and I get out of the Tennessee mountains on Tuesday. I’ll also be at AFUG Tuesday night.

More on FoxForward over at Kevin’s blog: http://cully.biz/. Alan said he might post too, so check out http://netcave.org/.