Editing Class (computer programming) (section)

===Partial===
In languages supporting the feature, a ''partial class'' is a class whose definition may be split into multiple pieces, within a single [[source code|source-code]] file or across multiple files.<ref name="mspartial">{{Citation|url=https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/partial-classes-and-methods|title=Partial Classes and Methods|work=C# Programming Guide|date=2015-09-19|author1=mairaw|author2=BillWagner|author3=tompratt-AQ|publisher=Microsoft|access-date=2018-08-08}}</ref> The pieces are merged at compile time, making compiler output the same as for a non-partial class.

The primary motivation for the introduction of partial classes is to facilitate the implementation of [[Automatic programming|code generators]], such as [[visual designer]]s.<ref name="mspartial"/> It is otherwise a challenge or compromise to develop code generators that can manage the generated code when it is interleaved within developer-written code. Using partial classes, a code generator can process a separate file or coarse-grained partial class within a file, and is thus alleviated from intricately interjecting generated code via extensive parsing, increasing compiler efficiency and eliminating the potential risk of corrupting developer code. In a simple implementation of partial classes, the compiler can perform a phase of [[precompilation]] where it "unifies" all the parts of a partial class. Then, compilation can proceed as usual. <ref>{{cite web | url=https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/partial-classes-and-methods | title=Partial Classes and Members - C# }}</ref>

Other benefits and effects of the partial class feature include:

* Enables separation of a class's interface and implementation code in a unique way.
* Eases navigation through large classes within an [[source code editor|editor]].
* Enables [[separation of concerns]], in a way similar to [[aspect-oriented programming]] but without using any extra tools.
* Enables multiple developers to work on a single class concurrently without the need to merge individual code into one file at a later time.<!-- (This enabling may be considered by some or most to be a detriment rather than a benefit for SoC can apply to programmers also).-->

Partial classes have existed in [[Smalltalk]] under the name of ''Class Extensions'' for considerable time. With the arrival of the [[.NET Framework|.NET framework 2]], [[Microsoft]] introduced partial classes, supported in both [[C Sharp (programming language)|C#]] 2.0 and [[Visual Basic .NET|Visual Basic 2005]]. [[WinRT]] also supports partial classes. <ref>{{Cite web |last=BillWagner |date=2024-11-14 |title=Partial Classes and Methods - C# |url=https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/partial-classes-and-methods |access-date=2025-02-06 |website=learn.microsoft.com |language=en-us}}</ref>