Oops foundation centralized coding in Visual DataFlex

OOPS Foundation Centralized Coding in Visual DataFlex:

One of the most fundamental concepts in oops programming [object oriented] is centralized coding so that unlike previous spaghetti code where the same calculation was formulated over and over again in different code segments, instead we now place the code in one spot so that if business rules change then we go to one spot, change the code, and we're done.

Earlier attempts at centralized coding involved gosubs where the same piece of code was reused, but with Visual DataFlex, utilizing datadictionaries, we have hooks in the finding process and constrain process for instance where the code is placed in a "stored procedure" along with all the other rules of the datadictionary class for a table. In Visual DataFlex methodology, which supports full message delegation, the find passes through a DDO [data dictionary object] which delegates the find to it's DD class code and utilizes the onconstrain method of the class as well as the object.

Technique: in order to fully utilize delegation, we "forward send" each message even if it is an "event" method.

The code described below takes a business rule exception to constrain a table by it's status which is used throughout a system in many places including windows data entry, batch processing, and webapp interfaces.

The beauty of Visual DataFlex database centric code is that this one event can be turned on or off by a property setting [business rule exception] in any of the above mentioned applications.

Here's some sample code:

This is intended as a "get-to-know features of Visual DataFlex" article.

Sincerely,

Peter Donovan

The NorthEast DataFlex Consortium

The NEDC: what it is!

The NEDC was formed in April of 2003 by a group of New England based Visual DataFlex custom application developers with varied specialties. It offers "the power of a large corporation without the large cost" for potential software partners/clients and is noteworthy as being the largest single resource for Visual DataFlex programming in the United States.

Why Choose the NEDC?
The NEDC is a group of independent Visual DataFlex (VDF) programmers that have joined in camaraderie to provide increased value and capabilities to their customers. The NEDC is not a conventional consulting firm, or even a legal entity, but “an almost virtual company”.
We think this concept works to make the NEDC an exceptional partner for your business, as we can offer the power of a large corporation without the cost.

· Experience: Collectively, the NEDC provides over 150 years of VDF (and other language) system development experience. Whether your needs are for an inventory, sales, manufacturing, time & attendance, ERP, or some other kind of system, we most likely have real life experience implementing similar systems.

· Skills: When working on a project, the person best suited to a particular portion is the one doing the work. NEDC members have worked in many environments: independent, small business, corporate and as a VDF instructor. This gives us real life understanding of how companies work. We all started in character mode (DOS based) DataFlex, so we know the language from the ground up. Most of us are also involved in testing of the newest version, so we know what’s coming.

· Project Types: We work in many different ways: conversions of character mode DataFlex systems to VDF, conversions of systems written in another language, maintenance of existing VDF systems, and whole new systems. Whether you need a classic Windows system, a Web-based system or a combination of the two, we can do it.

· Costs: Being a “virtual company” saves our clients money: no rent, tax burden or administrative costs to pass on. This means that we can work for a substantially lower hourly rate while providing excellent service. Of course it also means we can’t invite you to visit our expensive corporate headquarters! Instead, we come to you, which helps us get a better picture of how your company works.

· FLEXibility: The NEDC normally assigns one developer as project leader. If he goes on vacation or gets sick, another fills in. If you prefer to work with another developer as lead, simply ask and we’ll swap roles. This means that you are in the driver’s seat, not at the mercy of someone you’ve never met deciding that another project is “more important” than yours or that you will have to work with a particular person.

· Security: If you are used to working with a single developer you may worry about something happening to that person. In the NEDC, if something were to happen, another developer will switch into the role.

by:
Peter A Donovan
Charter Member of the NEDC (NorthEast DataFlex Consortium)