Run T4 text template programmatically

Question

Is there a way to programmatically run T4 text templates from code? I'm making a custom domain specific language and I would like the related text templates to run every time the user saves. Currently, this is what I do in the DSL model:

protected override void OnDocumentSaved(EventArgs e)
{
    IVsCommandWindow commandWindow = (IVsCommandWindow)this.ServiceProvider.GetService(typeof(IVsCommandWindow));
    if (commandWindow != null)
    {
        commandWindow.ExecuteCommand("TextTransformation.TransformAllTemplates");
    }
    base.OnDocumentSaved(e);
}

This works, but it has a really annoying side-effect. If the project has multiple DSL-documents, each with their related text templates, they will all be run, not just the ones that are affected by changes to the given DSL-document. This may not seem like such a big deal, but it causes source control to check out all the generated files, and if you have a lot of the documents, the transformation might actually take quite a while. Thanks for any help.

Answer 1

Jean-Mark Prieur from the DSL team explains how to do this with a custom tool in Part 4 of the DSL Tools Lab. You can also do this directly from the DSL model using ITextTemplating service. More on how template transformation works here.