The LA Fox Developer Newsletter

October 1997.

Why Visual MaxFrame

Professional?

by Michael Meer, MESLLC

Microcomputer Engineering Services, LLC (MES, LLC) recently

switched from using it own in-house framework to using G.E.

Consulting’s Visual MaxFrame Professional (VMP). Over the

last two years, we have developed a complete development

environment including RAD tools, built-in functionality and

consistent user interface. We are able to create basic, full

functioning screens in mere minutes. All of our forms are

consistent and easy to use. Why would we switch?

There are many reasons to switch including new features,

extensibility and client/server technology. VMP 3.0 has many

features of its interface that help our applications to appear

more commercial and professional. These features include

allowing the user to select their own font & color scheme,

remembering positions of each screen, grid column orders. The

base framework also allows the user to resize the window and

thus resize all of the controls, as well as the basic window

cascade and arrangement functions. VMP has built-in rightclick

menus that are sensitive to the object they are over. You can

“zoom” an editbox to view more of the data or you can cut and

paste in a textbox. All of these functionalities are built right into

the framework!

With the framework so rich in functions, you might wonderwby

you would even worry about extensibility. A perfect example of

where you might want to extend the framework shows up in the

rightclick menus. We like to give the user an ability to paste in

the date & time into memo field. This functionality is not built

into VMP, however, since you are given all of the source code to

VMP, you can add the code very easily. Also, suppose you

want every screen to have a green background. You can

subclass the classes included in VMP, change the base

background color and your ready to go!

Finally, the piece-de-resistance. Client/Server. VMP supports

dbf’s, local views and remote views harmoniously. In fact, you

can develop your application with local views and then “upsize”

it without much rewrite. The sample application included with

VMP shows many different approaches to both local data and

remote data forms. Our framework was designed with dbfs in

mind. Modifying itto handle local and remove views would have

been difficult. Transactions control is built into the classes as

well as several “hooks” to allow presave and postsave opera-

tions from within the transaction. VMP is client/server ready!

If you are looking for a framework with an easy learning curve,

we recommend VMP. The manual has many examples and

you’ll get a fully functioning sample application that gives many

approaches to the same problem. Each screen in the sample

application is well documented in functionality as well as

procedurely.

Codebook (Con't from page 5)

The documentation provided by the book provides a reasonable

basis to learn the Codebook foundation, but the software

implementation is a couple degrees of magnitude more complex

and not heavily commented. There is no direct support available

but a strong community of developers using Codebook helps fill

this gap with peer support. Try Compuserve Fox Users Forum,

and Ed Leaf’s new CB3 Web Support Forum at http:II

www.leafe.com/cb3/forum/default.html I also recommend

downloading Codebook for Mere Mortals by Kevin and Nicole

McNeish.

Selecting Function or Visual conversion is the most important

decision you must make.

The Functional conversion makes it easier for the d2veloper in

the short run, but can require more work in the long run when

you want to begin to take advantage of the new features of

Visual FoxPro 5.0. The Converter makes the form a “backward

compatible” form, which has attributes unique to this type of

form.

In the Visual Conversion, none of your existing snippet code

(Open, Valid, etc.) is mapped to the corresponding methods and

events. You will have to cut and paste your procedural code. But

you won’t have to modify the converted form to take advantage

of the new event model.

Total rewrite - Hold your breath and jump in

Well, not exactly total. You can, of course, keep the data

structures and business rules you have already developed. But

you will want to take the time to re-architect your application to

take advantage of 00 analysis and design techniques. This is

the most costly (and time consuming) approach, but it is also

the most powerful, flexible and the one that will allow you to

take advantage of all the new features of Visual FoxPro 5.0.

In addition, you will find that you can eliminate hundreds

(thousands?) of lines of code because Visual FoxPro 5.0 has

built-in functionality that you used to have to code yourself.

VFP 5.0 offers a wealth of new capabilities and a great object

oriented programming environment, but there is a learning curve.

With a reasonable understanding of object oriented program-

ming as it is implemented in Visual FoxPro, I believe one can

minimize the transition by utilizing one of the development

foundation environments available such as “The Visual FoxPro 3

Codebook” or “Visual MaxFrame.

Foundations are not necessarily rapid development tools, but a

good framework that will save you lots of time. With a good

foundation, you will have many of the tools necessary for

building a solid application available to you.

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