This post originated from an RSS feed registered with .NET Buzz by Peter G Provost. Original Post: CodeSmith + CodeDom Feed Title: Peter Provost's Geek Noise Feed URL: /error.aspx?aspxerrorpath=/Rss.aspx Feed Description: Technology news, development articles, Microsoft .NET, and other stuff... Latest .NET Buzz Posts Latest .NET Buzz Posts by Peter G Provost Latest Posts From Peter Provost's Geek Noise

Yesterday Steve Eichert wrote:

This past week while working on a re-write of the framework that prompted the initial evaluation of Emit vs. CodeDOM I decided to revisit the debate.  After "thumbing" my way through the documentation of the CodeDOM classes I came across the ICodeCompiler.CompileAssemblyFromSource() method.  Rather then emitting OpCodes I decided to create a couple of templates for my code and use the ICodeCompiler to genearte an in memory assembly.  While I did miss the process of pushing things onto the call stack using OpCodes, I realized how much more productive I was creating "C# templates" for my code and compiling them with the CodeDOM classes.

As I started to think about this, I decided to try this out. Since CodeSmith will produce a template assembly that I can call from code, this should be easy as pie!

I started by creating this simple CodeSmith template:

<%@
CodeTemplate Language="C#" TargetLanguage="C#" Description="" %> 


<%@
Property Name="ClassName" Type="System.String" Default="MyClass"

Category="Options" Description="" %> 


<%@
Property Name="SampleStringProperty" Type="System.String"

Default="SampleString" Category="Options" Description="" %> 


public class <%=ClassName%> 


{ 


public string <%= SampleStringProperty %> 


{ 


get { return _<%=SampleStringProperty%>;
} 


set { _<%=SampleStringProperty%> =
value; } 


} 




private string _<%=SampleStringProperty%>; 


}

Then using CodeSmith, I created an assembly from my template. Basically this creates a DLL that you can reference from your code that contains the code generation class defined by the CST file.

Once that was done, I created a simple forms app, added a button, and put the following code in the click handler:

private void button1_Click(object
sender, System.EventArgs e) 


{ 


CodeSmithTemplates.SimpleTemplate template = 


new CodeSmithTemplates.SimpleTemplate(); 


template.ClassName = "MyClass"; 


template.SampleStringProperty = "MyProperty"; 


string source = template.RenderToString(); 




CSharpCodeProvider cSharpProvider = new CSharpCodeProvider(); 


ICodeCompiler compiler = cSharpProvider.CreateCompiler(); 




CompilerParameters options = new CompilerParameters(); 


options.GenerateInMemory = true; 




CompilerResults results = 


compiler.CompileAssemblyFromSource( options, source ); 




if( results.Errors.HasErrors ) 


{ 


StringBuilder sb = new StringBuilder(); 


foreach( CompilerError error in results.Errors
) 


{ 


sb.Append( String.Format("{0} - {1}\n", error.Line, 


error.ErrorText ) ); 


} 




MessageBox.Show( sb.ToString(), "ERROR" ); 


return; 


} 




Assembly assembly = results.CompiledAssembly; 


object o = assembly.CreateInstance( "MyClass" ); 




Type t = o.GetType(); 


t.InvokeMember( "MyProperty", BindingFlags.SetProperty, null, 


o, new object[] { "Test!" } ); 


object result = t.InvokeMember( "MyProperty", 


BindingFlags.GetProperty, null, o, null ); 




MessageBox.Show( result.ToString() ); 




}

That's it! Granted I didn't do anything particularly complex with it, but it is a very effective way to combine template generated code (a la CodeSmith) with CodeDom. Enjoy!