|Original author(s)||Novell, Xamarin, Microsoft|
v2.0.5 / June 13, 2019
|Operating system||Linux, Windows|
|Website||Code Generation and T4 Text Templates|
Text Template Transformation Toolkit (usually referred to as "T4") is a free and open-source template-based text generation framework. T4 source files are usually denoted by the file extension ".tt".
T4 is used by developers as part of an application or tool framework 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 .NET code and string literals in it, this is parsed by the T4 command line tool into .NET code, compiled and executed. The output of the executed code is the text file generated by the template. T4 can also be completely run within the .NET applications via the use of the TextTransformation class which eliminates the need for the end user to have Visual Studio installed.
T4 is used within Microsoft in ASP.NET MVC for the creation of the views and controllers, ADO.NET Entity Framework for entity generation, and ASP.NET Dynamic Data. It is also used outside of Microsoft in projects such as SubSonic.
There are four types of controls handed by the T4 template transformation engine.
||Instructions for the transformation engine|
|Standard control blocks||
||Code to be executed (e.g. loops)|
|Expression control blocks||
||Expressions evaluated and converted to a string|
|Class feature control blocks||
||Class and function definitions|
This section contains content that is written like an advertisement. (May 2017)
Microsoft has often been criticized[by whom?] for the lack of tooling support for T4 within the Visual Studio IDE, and relies on third parties namely Tangible Engineering, however later revisions have included better tooling support.