![]() ![]() Language features that allowed instances of a class to be customised without subclassing, in two ways: first, through the use of properties, allowing instances of an object to have its own fields (such as a caption) easily changed through streaming second, by allowing events - method pointers called at specific places in code - to be handled by another object that is, the method pointers were attached to an object instance.A form designer that saved to a stream, saving the description of the objects not the code required to create them, with objects capable of self-creation when streaming the description back in.A streaming framework, allowing an object and subobjects to be streamed to text or binary format - TComponent, the root class of the VCL framework.The combination of the Delphi language and the VCL framework written in that language addressed these by: Finally, a visual user interface arguably should be designed visually, and yet most tools to do so - at the time, mainly Visual Basic - did so in terms of the designer outputting code, creating a fragile, un-manually-editable situation - a problem that still persists today with many UI frameworks, particularly C++-based ones such as Qt. (For context, the Delphi variant of Pascal had a number of innovative object-oriented features, such as properties and runtime type information, inspired by Modula and Smalltalk.) At the time, much UI code work required creating classes inheriting from other classes, and customized objects were often not reusable (for example, a button that performs a specific action cannot be reused in a different application.) UI code was also complicated, forcing the programmer to understand and use the Windows API, manage GDI resources, etc. ![]() OWL, a similar framework to MFC, required writing code to create UI objects.Ī key aim of the VCL combined with the Delphi language was to change the requirements of building a user interface. Up until that point, Borland's Turbo Pascal for DOS and Windows was largely a procedural language, with minimal object-oriented features, and building UI frameworks with the language required using frameworks like Turbo Vision and Object Windows Library. In 1995 Borland released Delphi, its first release of an Object Pascal IDE and language. The VCL was developed by Borland for use in, and is tightly integrated with, its Delphi and C++Builder RAD tools. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |