Thursday, 18 December 2008

Domain Specific Languages (VI)

Generating Code from the Model

The DSL will now be tested by producing a model, and developing a T4 template to generate code from the model.
  • In the DSL (running under the Visual Studio Experimental Hive), open Sample.mydsl, and draw a model of a Male class inheriting from a Person class, and a Female class inherting from the same Person class. Set the Visibility property of all classes to public.
  • Open In text templates, you indicate directives by using <#@ tags, statements with <# tags, and expressions with <#= tags.
  • Change the output extension directive to .cs.
  • Comment out the generated material line.
  • Change the foreach loop to that shown in the image below. To use code outlining and intellisense, download and install the Clarius T4 Editor. The loop states that for each Class in the ClassModel, display the class Visibility, the word class, the class Name, and then if the class has a BaseClass, to display the BaseClass name after a colon.

  • Save the T4 template and examine the generated code (MyDSLSample.cs). The generated code lists the class visibility, the class name, and the base class (if applicable).

In this series of posts I've shown you how to create and customize a simple Domain Specific Language by using the DSL Tools that are part of the Visual Studio SDK. There’s a lot more to DSLs than covered here, including more extensive customization, adding and using coherence rules, performing model validation both interactively and on request, writing more extensive T4 templates, and deploying a DSL by obtaining and adding the necessary package load keys, and creating a DSL setup project. For more information on these topics, see the VSX website.

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