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IF Programming Series, First Installment: TADS

© Mark Silcox

One of the things that I've always found attractive about the IF community is the substantial overlap between producers and consumers. Virtually everyone who's ever made his or her way through one or two works of IF has eventually felt the urge to write one of their very own. One of the most valuable services that a site like this one might be able to perform for newcomers to IF, then, is to provide a basic acquaintance with some of the many interactive fiction authoring systems that are out there and available for use. This week's article will be the first of a series designed to fulfill that need. I'll begin with the system I'm most familiar with myself - the IF programming language TADS - and turn to others as my own level of experience and expertise slowly goes upward.

So what is TADS? Well, it was originally designed by Mike Roberts for distribution as shareware by his company 'High Energy Software.' If you've already been around the IF block a few times you might recognize this name - Mr. Roberts is himself a highly gifted and clever author of such classic IF works as "Ditch Day Drifter," "Perdition's Flames" and, more recently, "The Plant." In 1996, he generously decided to made TADS available free to whoever wanted it. Everything that you need to compose, compile, and run IF works in TADS are available via the TADS homepage, at http://www.tela.bc.ca/tela/tads.

TADS is what computer types refer to as a high-level, object-oriented programming language, designed specifically for the production of IF. 'High Level' just means that is requires a fairly sophisticated compiler to translate it's code into the numerical language understood by your PC. It's the 'object oriented' nature of this and other IF languages that confuses many folks who haven't got much experience with the finer points of programming. Object-oriented languages are usually distinguished from 'procedural' programming languages like BASIC or the various members of the 'C' family. In procedural languages, programs are a series of instructions that the computer interprets and follows in serial order. A TADS program is a list of 'objects' that need be given in no fixed order (more or less), together with coded descriptions their properties and how they relate to other objects described by the program. A block of code written in a object-oriented language to describe one room in an IF game, containing a dad bat and a Jell-O mold, might look something like this:

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