What is "t4"

Text Template Transformation Toolkit (normally referred to as T4) is a template-based text generation structure, included in Visual Studio. T4 source files are usually identified by the file extension ". tt".

T4 is used by developers as part of an application structure or tool to automate the creation of text files with a variety of parameters. These text files can ultimately be any text format, such as code (for example C #), XML, HTML or XAML.

T4 uses a custom template format, which can contain code. NET and literal strings in the same template, which is parsed by the T4 command line tool in code. NET, compiled and executed. The output code run are text files generated by the template. T4 can also be run completely within the applications. NET by using the class TextTransformation that eliminates the need for the end user to have Visual Studio installed.

T4 is used within Microsoft ASP.NET MVC on for creating Views and Controllers, for entity generation for the Entity Framework, and ASP.NET Dynamic Data. It is also used outside of Microsoft in projects such as Subsonic.

T4 templates is also supported in Monodevelop.

Source: Wikipedia.