The class library in Borland Delphi is known as the Visual Component Library
. Delphi’s class library is written in Delphi, and source
is shipped with Delphi. This class library is highly regarded as being simple to use and flexible. It and does a good job of hiding the details of the Windows API
“The Visual Component Library (VCL) is a hierarchy of classes—written in Object Pascal and tied to the Delphi IDE—that allows you to develop applications quickly.” – Delphi help
All objects descend from TObject by definition, all objects that you can drop on a form descend from
TComponent, and anything that wraps a windows control descends from
“Despite its name, the VCL consists mostly of nonvisual objects.” – Delphi help.
Many classes in the VCL have non-visual roles, for e.g. Exception claase based at
Exception list objects like
TObjectList and Operating System objects like
TCriticalSection and the longest-named of them all:
You may have noticed that it is convention for all Delphi class names to begin with T for type, with the exception of Exceptions.
The thing that I don't like is that is not open source - even when you find a bug and know how to fix it, convincing Borland of that is a huge pain in the rear.