How to disable #line directives being written to the T4 generation output file

问题

I have encountered a small problem with my T4 code generation.

I have broken my T4 templates up into separate files and placed them in various directories, I have done this so parts of my code generation may be re-used in multiple projects, e.g. model generation, repository generation and service generation all include a core EntityGeneration.tt file.

Unfortunately, when TextTemplating resolves my nested includes, it builds up a long #line pre-processor directive in its generated .cs file, combining all of the relative paths to the lowest level included file.

Unfortunately, as this path is built up with relative paths, it ends up needlessly long, so long in fact that it exceeds the maximum path length (Windows 7).

Here is the line at fault from the generated code in case you are interested:

#line 3 "C:\VS2010\AlbatrossTravelGroup\ASC\AlbatrossTravelGroup.ASC.BusinessRules\Services\Contracts\..\..\..\..\AlbatrossTravelGroup.BusinessRules\Services\Contracts\..\..\..\AlbatrossTravelGroup.Models\Repositories\Contracts\..\..\../AlbatrossTravelGroup.Common/CodeGeneration.tt"

My question is this, how can I disable these directives being written to the generated code file? Failing that, how can I avoid this problem without changing my file structure?

回答1:

Visual Studio 2012 adds the linePragmas="false" template directive:

<#@ template language="C#" linePragmas="false" #>

http://msdn.microsoft.com/en-us/library/gg586945(v=vs.110).aspx

Still not sure how to do this in VS2010 which I'm stuck with at work.

回答2:

I'm not sure this will fix your problem. I don't have a great deal of experience with T4. That said, I'm using it build a number of files in my project and I have not run into the problem you are running into.

In my case, I have a bunch of individual .tt files that render individual files in my project.

The way I'm doing it is as follows: I have a SaveOutput method (stolen from somewhere on stackoverflow, I believe):

void SaveOutput(string outputFileName)
{
    if (!string.IsNullOrEmpty(outputFileName))
    {
        string templateDirectory = Path.GetDirectoryName(Host.TemplateFile);
        string outputFilePath = Path.Combine(templateDirectory, outputFileName);
        string output = this.GenerationEnvironment.ToString();
        File.WriteAllText(outputFilePath, output); 
    }

    this.GenerationEnvironment.Remove(0, this.GenerationEnvironment.Length);
}

So in my main .tt file, I have <#@ includes... #> for my various .tt files for the individual files. For example: <#@ include file="DataObjectInterface.tt" #>

<#+
    public string GenerateInterfaceDataObject(sqlTable table)
    {
        string ifaceName = "I" + table.ObjectName;
        if (table.GenerateInterfaceObjectAsBase)
        {
            ifaceName += "Base";
        }
#>
using System;

namespace <#= InterfaceNamespace #>
{
    public interface <#= ifaceName #>
    {
<#+
        foreach(sqlColumn col in table.Columns)
        {
#>
        <#= GetColumnCSharpDataType(col) #> <#= col.FieldName #> { get; }
<#+
        }
#>
    }
}
<#+
        return RootPath + @"\AutoGenerated\" + ifaceName + ".cs";
    }
#>

Then, in my main .tt class, I simply make a call like this:

string filePath = GenerateInterfaceDataObject(table);
SaveOutput(filePath);

Not sure if this method of breaking your templates up will work for your needs, but it worked for mine and I haven't run into any problems with it yet.

I should clarify that my main .tt file doesn't actually generate anything from itself. It is not itself a template. It simply loads each of the templates and generates the files from the the other templates.

来源：https://stackoverflow.com/questions/7887081/how-to-disable-line-directives-being-written-to-the-t4-generation-output-file

标签

path

c-preprocessor