Editing Visual Component Library (section)

== Technology ==
VCL forms a [[Class (object-oriented programming)|class]] hierarchy with a common [[Inheritance (object-oriented programming)|ancestor]], the TComponent class (which [[Inheritance (object-oriented programming)|inherits]] from TObject, the root class in [[Delphi (programming language)|Delphi]] [[Object Pascal]]). This is a common approach shared by the [[Java programming language]], [[Smalltalk]], [[C Sharp (programming language)|C#]] and many other [[object-oriented]] programming languages.

VCL components cover Windows controls like windows (TForm [[Class (object-oriented programming)|class]]), controls (e.g., TButton, TCheckBox, TLabel classes) as well as [[database]] access (e.g., ADO or IBX components) or Internet connections ([[Internet Direct (Indy)|Indy]] components). The component approach allows programmers to extend the VCL with many visual and non-visual additional components. There is a large number of free and commercial component packages. Among them are [[Project JEDI (Programming)|JEDI]], [[TMS (Programming)|TMS]], [[Developer Express (Programming)|Developer Express]], [[Mitov Software (Programming)|Mitov Software]], [[Raize Software (Programming)|Raize Software]], [[TurboPower (Programming)|TurboPower]], [[IOComp (Programming)|IOComp]], [[SDL (Programming)|SDL]], [[DA-SOFT Technologies (Programming)|DA-SOFT Technologies]] and many others.

While not all VCL components are [[thread-safe]], VCL supports [[Thread (computing)|multi-threading]] too. One example is the built in multi-threading support of the [[OpenWire (library)|OpenWire]] VCL library.

VCL provides native support for [[Property-Method-Event|PME]] (properties, methods and events) model at the [[.NET Framework|.NET]] level.{{Citation needed|date=August 2009}}

Much of the [[.NET Framework|.NET]] design, especially WinForms, is modeled after the VCL. One of the main architects of the first Delphi versions, [[Anders Hejlsberg]], was hired by [[Microsoft]] and became one of the main architects of .NET. This became the subject of a lawsuit: at the time (1996), "Borland alleged that Microsoft had hired 34 Borland employees over the past 30 months in order to steal Borland trade secrets. Borland also claimed that Microsoft offered and delivered expensive lures to Borland workers. In two cases, incentives topping $1 million were involved."<ref name="DotNetIsDelphi">{{Cite web|url=http://delphi.about.com/od/delphifornet/a/conspiracydnet_2.htm|series = Delphi Programming - Back to the future|title=Microsoft's .Net IS Borland's Product (2/3)|first=Zarko|last=Gajic|archive-url=https://web.archive.org/web/20050918163935/http://delphi.about.com/od/delphifornet/a/conspiracydnet_2.htm|archive-date=September 18, 2005|url-status=dead}}</ref> According to Zarko Gajic, the bonus was three million dollars in Anders' case.<ref name="DotNetIsDelphi"/> Many Delphi developers find C# quite familiar, due to the design similarities.<ref>{{Cite web |url=http://www.glennstephens.com.au/tech/CSharp4DelphiDevelopers.pdf |title=C# for Delphi Developers |first=Glenn |last=Stephens |access-date=2014-05-28 |archive-date=2014-01-26 |archive-url=https://web.archive.org/web/20140126115859/http://www.glennstephens.com.au/tech/CSharp4DelphiDevelopers.pdf |url-status=dead }}</ref>