T4: Is it possible to use a script to fill in a template, while still providing sections via the script?

Question

I have a template that generates a class and a complementary interface to go with it from a script like so:

<#@ template language="C#v3.5" hostspecific="True" debug="True" #>
<#@ output extension="cs" #>
<#@ include file="T4Toolbox.tt" #>
<#@ include file="../BusinessObjectTemplate.tt" #>
<#
BusinessObjectTemplate template = new BusinessObjectTemplate();
template.BusinessName="Priority";

template.PropertyList=new Dictionary<string,BusinessPropertyT4>{
    {"Value",new BusinessPropertyT4("byte")},
    {"Display",new BusinessPropertyT4("string")},
};
template.TopRegionText="internal ModelPriority(byte value, String display)\r\n\t\t{\r\n"+
    "\t\t\tValue=value;\r\n"+"\t\t\tDisplay=display;\r\n"+ "\t\t}";
template.Render();
#>

How would I generate the TopRegionText(constructor) from the script without feeding it a direct string and have it go into the right place in the template?

Answer 1

Assuming that you would prefer to use templating functionality of T4 to generate the constructor, you can define a virtual method (i.e. GenerateTopRegionText) in BusinessObjectTemplate class and call it from BusinessObjectTemplate.TransformText method. Having done that, you can override it like so:

<#+
class PriorityTemplate: BusinessObjectTemplate
{
    override void GenerateTopRegionText()
    {
#>
    internal ModelPriority(byte value, string display)
    {
        Value = value;
        Display = display;
    }        
<#+
    }
}
#>

More here.