Getting a CodeDomProvider in an MSBuild Task

Trying to get the correct CodeDomProvider inside of an MSBuild task wasn’t as easy as I would have liked. Well actually the code itself is pretty simple but finding out how to actually do it was difficult. There doesn’t appear to be a profusion of people doing such a thing so the blogosphere and forums are fairly sparse with related information. After messing around with it for a couple of hours I think I finally found a pretty reliable (aka it doesn’t feel like a dirty hack) way to do it.

<Project xmlns=“http://schemas.microsoft.com/developer/msbuild/2003&#8221;>   <!–Reference the assembly where our tasks are defined–> <UsingTask TaskName=“MetaSharp.MSBuild.TemplateTask” AssemblyFile=“$(MSBuildExtensionsPath)\MetaSharp\MetaSharp.MSBuild.dll” />   <!–Compile target (this is the target that calls the compiler task)–> <Target Name=“BeforeBuild”>     <Message Text=“Building: @(MetaSharpTemplate)” />     <TemplateTask Templates=“@(MetaSharpTemplate)” Language=“$(Language)”>       <Output TaskParameter=“Generated” ItemName=“Compile” />     </TemplateTask> </Target> </Project>

using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Build.Utilities; using Microsoft.Build.Framework; using System.Collections; using System.CodeDom; using System.CodeDom.Compiler;   namespace MetaSharp.MSBuild {       publicclassTemplateTask : Task       {             // Properties             [Required]             publicITaskItem[] Templates { get; set; }               [Required]             publicITaskItem Language { get; set; }               [Output]             publicITaskItem[] Generated { get; set; }               publicoverridebool Execute()             {                   base.Log.LogMessage(0, “Building MetaSharp templates.”);                     if (this.Language == null || string.IsNullOrEmpty(this.Language.ItemSpec))                   {                         base.Log.LogError(“You must have a Language PropertyItem defined somewhere in your project files to specify which CodeDomProvider to use (i.e <Language>C#</Language>)”);                         returnfalse;                   }                     CodeDomProvider provider = FindProvider(this.Language.ItemSpec);                     returntrue;             }               privateCodeDomProvider FindProvider(string language)             {                   CodeDomProvider[] providers = (from info inCodeDomProvider.GetAllCompilerInfo()                                                                from l in info.GetLanguages()                                                                where l.ToUpperInvariant() == language.ToUpperInvariant()                                                                selectCodeDomProvider.CreateProvider(l))                                                                .ToArray();                                     CodeDomProvider provider = null;                   if (providers.Length == 0)                   {                         Log.LogError(“Unable to find a valid CodeDomProvider for this project type. Try adding a valid Language property item to your msbuild project file”);                   }                   elseif (providers.Length > 1)                   {                         // It would be surprising if this ever happened…                         Log.LogError(“Found multiple valid CodeDomProviders for this Language type. Try adding a less ambiguous Language property item to your msbuild project file”);                   }                   else provider = providers[0];                     return provider;             }       } }