Real Classes for Visual Basic

Rick Grehan

Visual Basic 4.0 added a touch of class to its environment, but the implementation was incomplete. The raison d'être of VB 4.0 classes was to serve as a framework for building OLE automation servers. Consequently, some class-like characteristics--most important, inheritance and polymorphism--were not built into VB 4.0 classes.

Sheridan Software's ((516) 753-985) ClassAssist adds inheritance and polymorphism in such a way that VB 4.0 is not aware that these additional capabilities have been infused. For example, suppose I've declared a class Polygon and I want to derive from it a subclass Rectangle. Rectangle can override Polygon's methods, but should Rectangle wish to explicitly call a Polygon method, it does so by using the syntax Polygon_<methodname > . Polymorphism is achieved through a clever naming convention applied to source code.

However, more that just source code is involved. ClassAssist keeps all classes in a structured library that can be shared across a network. To perform any edits to a class, you must first check it out of the library; when you do so, you can optionally lock the class so that other users are barred from checking it out.

ClassAssist's Class Explorer window is the gateway into the ClassAssist IDE, a structured collection of windows through which you create and edit classes, their properties, and their methods.

ClassAssist automatically generates the .CLS files that VB 4.0 uses and will import classes into your VB 4.0 project at your command; it even keeps everything in synchronization. That is, if you edit a ClassAssist-generated class from VB 4.0, ClassAssist sees the change and asks if you want to pass your edits on to the ClassAssist library. Bundled with ClassAs sist are the WinAPI Oblets, a collection of objects crafted by in-process DLLs that encapsulate significant parts of the Windows API. ClassAssist is well worth its $249 price.

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A Touch of VB Class

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