Creating a GNUstep Project

I got the book Developing Business Applications with OpenStep. It's not all I would have wished for. You don't get to your first sample application until Chapter 7, and wading through the first 6 chapters is a bit of a chore. I found Chapter 4 on the Application Kit contains no sample code at all, but it is good for insomnia. Anyway, now that I'm to Chapter 7, Building an Application, I am going to try creating the sample application (PayPerView) which is their only working example and which they add to later in the book when they introduce more advanced topics (this may be the last chapter I read in the book).

PayPerView has a class called ProgramController, which isn't really what it sounds like. The word “program” in this context refers to a pay-per-view tv program. The ProgramController keeps a list of Program objects and interacts with the UI. There is also an OrderController, which controls the process of a user placing an order for a Program. Why there isn't also an Order class I do not know. More classes are added later in the book when the application is expanded to persist to a database and one to use distributed objects. (I am not actually interested in either of these at this time.)

First thing to do is to create the project. In GNUstep, we do this through ProjectCenter. Just like the original Project Builder as described in the book, you choose New... from the Project menu. (Sorry. I am too lazy to paste screen shots in here right now.) I had already created a folder in my home directory called projects_objc. GNUstep creates a GNUstep folder in your home directory for its own configuration files, so better to keep your code separate from that. I'm going to call my application PayPerView and define it as type Application. The default project type in GNUstep is not application but Aggregate. An aggregate project contains multiple sub-projects or “make targets”, meaning it will have multiple executable applications. (You can add new subprojects later even if you select Application at this time.)

On the project window there are noticeable differences between GNUstep's ProjectCenter (PC) and Project Builder. For example, the icons are different. (Still too lazy to do any screen shots, so you'll have to trust me until I feel like adding them.) PC has a screw driver instead of a hammer icon for the Project Builder icon. The remaining icons in GNUstep are different but still reminiscent of the original. That's okay, because there were even significant differences between the NeXT Project Builder and the one that Sun created for Solaris (and, of course, Apple has made significant changes in XCode although it still has the familiar hammer icon). They are the Project Launcher (or Run) icon, the Loaded Files icon, the Project Finder icon, and the Project Inspector (or Attributes) icon.

BTW, at this point if you've never seen XCode it might be best just to ignore it for a while, because it looks so nice while GNUstep looks the same as it did 10 years ago. Just remember that GNUstep is free and not commercially supported.

When you click on Interfaces (as instructed in the book), you will see instead of a .nib file some files related to Gorm, GNUstep's Interface Builder. You get into Gorm by double-clicking on the .gorm file. (Sorry. I am still too lazy to paste screen shots in here right now.)

The format of .nib (NeXT Interface Builder) files were difficult to reproduce in GNUstep, because there is no real .nib file standard. The .nib file is actually just a file containing serialized objects. Duplicating it exactly would have been difficult and possibly required reverse-engineering which probably would create legal problems. However, in newer versions of Gorm, you can at least export to a Nib file by selecting Save As on the Documents menu in Gorm. (I don't think you can import a Nib file created in Apple's XCode and expect to be able to use it in Gorm.)

Anyway, so I will continue later with using Gorm and maybe stop being lazy and add screen shots.