The dBASE Book is aimed at developers of dBASE applications from
beginner to advanced, and will assist a developer to get up to speed
quickly with the dBASE Object model. It covers application design from
design to deployment. The Second Edition (now available) fixes errors in the text (and code samples); addresses some issues with Windows Vista; includes updates to aspects of the software (through 2.6.2); includes a new chapter on the grid; a re-written chapter on deployment; and a more useful index.
dBASE has always had a programming language. Over the last few years this language has been given an acronym of “dBL” (for dBASE Language).
Developers who have worked with dBASE over the years are probably more
accustomed to what is usually called Procedural Code or Procedural
Programming – particularly if you programmed in dBASE for DOS (any version).
This type of coding works from the top of a program down to the bottom,
and then it stops. Inside the code there may be calls to other code, or
loops, but ultimately the code goes from the top to the bottom.
Object Oriented Programming (OOP) changes this way of coding
completely. With a new way of coding come many new terms. These terms
can be confusing, but when looked at a bit at a time, and in the right
sequence, it all comes together and starts to make sense.
One of the great features of dBASE and dBL is that there are multiple
ways to perform most tasks, and you can combine old coding techniques
with new. While this book will focus heavily on OOP, if your code works
and you feel no need to update it to OOP coding techniques, there is no
reason to feel you have to change your code.
In this chapter you will be exposed to some code in order to understand
basic OOP concepts. Some commands may actually be ones that are not
directly related to OOP, but are necessary just to show how it works.
In order to assist, many examples in this chapter are based on some
visual objects in dBASE, but there are some examples that are not
visual, just to help explain some of the terms and ideas being
demonstrated. If you wish to actually try the examples, most of them
can be executed from the Command Window of dBASE PLUS.
Ken Mayer has used dBASE both as a hobbyist and as a professional coder for 24 years, starting with dBASE III+ and working up to dBASE PLUS.
Ken worked for Borland, Intl. for two years as a Senior Quality Assurance Engineer on the Intrabuilder and dBASE products, and also worked for five years for dBASE Inc. as a Senior Quality Assurance Engineer, also working on dBASE. Ken was a contributing editor to dBASE Advisor magazine for the one and a half years or so it was in publication.
He served on Borland’s TeamB (volunteer technical support) when Borland owned dBASE, and has helped many in the dBASE developer community. At this time he is a member of the dBVIPS for dataBased Intelligence, Inc., doing the same things he did with TeamB. He authored a good portion of the Knowledgebase articles that ship with dBASE PLUS, and authored the original dBASE PLUS tutorial. Some of the material in this book will look suspiciously familiar to any who have used the Knowledgebase.
Ken has also been the librarian of a freeware library of code made available to all dBASE developers called the dBASE Users’ Function Library Project (dUFLP). He has been a speaker at Borland and other conferences on dBASE, speaking about coding techniques.
He is pursuing opportunities where they may lie – having spent only a small portion of his time after being laid off actually making any money, although putting a lot of effort into this book.
When not working or trying to find work, Ken is very active in the Society for Creative Anachronism, Inc. (http://www.sca.org), and enjoys movies, games, and reading.
Ken lives in Walnut Creek, CA with his wife Carolyn Eaton and their two cats Rebo and Zootie.