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A tool for dynamic compile and run of C# or VB.NET code

By , 24 Mar 2004
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Introduction

This program compiles a piece of code in memory and runs it dynamically, so you can test some C# or VB.NET code without having to create a new project or solution.

Background

Very often, we need test a piece of code ( C# or VB.NET ). In .NET environment, we use "csc" or "vbc" command; In VS.NET, we create a new project or solution, and create many other files. Both of them are tedious, especially when we test a simple program. One way is produced by jconwell, "Dot Net Script". He uses XML files ( named "dnml" ) which include C# or VB code. In that method, a dnml file is parsed and the code is compiled in memory. That's a good idea! However, it is a little inconvenience because it needs to build a new file. Here we provide a tool based on his work. The tool has these characters:

  • It can load C# or VB code file, compile the code in memory, and run the code through a static method ( "entry point" );
  • As for VB.NET code, if it is a "Form", the tool can add "Main()" to run the form;
  • It uses a new thread to run the code;
  • It has a visual interface( see blow ).

Using the tool

As the picture blow shows, press button "Open..." can Open C# or VB.NET file; press button "Paste" to paste code from clipboard to text area; check box "C#" means if the code is C# language; the text box is filled with entry point ( a static method in C# or a shared Sub or Function in VB.NET ); press button "Run!" to compile and run the code.

How it woks

The main class of the program is CompileEngine, which has such a constructor

  public CompileEngine( string code, LanguageType language, string 

entry )
  {
   this.SourceCode = code;
   this.Language = language;
   this.EntryPoint = entry;
  }

Run is an important method. It includes three steps: PrepareRealSourceCode, CreateAssembly and CallEntry.

  public void Run()
  {
   ClearErrMsgs();

   string strRealSourceCode = PrepareRealSourceCode();

   Assembly assembly = CreateAssembly( strRealSourceCode );

   CallEntry( assembly, EntryPoint );

   DisplayErrorMsg();

  }

PrepareRealSourceCode has two functions: to add "Imports" statements and to add "Sub Main" for VB.NET Windows Forms.

  private string PrepareRealSourceCode()
  {
   
   string strRealSourceCode = "";

   // add some using(Imports) statements
   string strUsingStatement = "";
   
   if( Language == LanguageType.VB )
   {
    string [] basicImportsStatement = {
       "Imports Microsoft.VisualBasic",
       "Imports System",
       "Imports System.Windows.Forms",
       "Imports System.Drawing",
       "Imports System.Data",
       "Imports System.Threading",
       "Imports System.Xml",
       "Imports System.Collections",
       "Imports System.Diagnostics",      
    };
    foreach( string si in basicImportsStatement )
    {
     if( SourceCode.IndexOf( si ) < 0 )
      strUsingStatement += si + "\r\n";
    }
   }

   strRealSourceCode = strUsingStatement + SourceCode;

    // for VB Prog, Add Main(), So We Can Run It
   if( Language == LanguageType.VB && EntryPoint == "Main" &&
    strRealSourceCode.IndexOf( "Sub Main(") < 0 ) 
   {
    try
    {
     int posClass = strRealSourceCode.IndexOf( "Public Class ")+ 
        "Public Class ".Length;
     int posClassEnd = strRealSourceCode.IndexOf( "\r\n", posClass );
     string className = strRealSourceCode.Substring( posClass, 
          posClassEnd - posClass );
     int pos = strRealSourceCode.LastIndexOf( "End Class");
     if( pos > 0 )
      strRealSourceCode = strRealSourceCode.Substring( 0, pos ) + @"
          Private Shared Sub Main()
           " + "Dim frm As New " + className + "()" + @"
                   If TypeOf frm Is Form Then frm.ShowDialog()
          End Sub
         " + strRealSourceCode.Substring( pos );
    }
    catch{}
   }

   return strRealSourceCode;

  }
CreateAssembly compile the source code and make assembly in memory.
  
        // compile the source, and create assembly in memory
        // this method code is mainly from jconwell, 
        // see http://www.codeproject.com/dotnet/DotNetScript.asp
        private Assembly CreateAssembly(string strRealSourceCode)
        {
            //Create an instance whichever code provider that is needed
            CodeDomProvider codeProvider = null;
            if (Language == LanguageType.CSharp )
                codeProvider = new CSharpCodeProvider();
            else if( Language == LanguageType.VB )
                codeProvider = new VBCodeProvider();

            //create the language specific code compiler
            ICodeCompiler compiler = codeProvider.CreateCompiler();

            //add compiler parameters
            CompilerParameters compilerParams = new CompilerParameters();
            compilerParams.CompilerOptions = "/target:library"; 
                   // you can add /optimize
            compilerParams.GenerateExecutable = false;
            compilerParams.GenerateInMemory = true;            
            compilerParams.IncludeDebugInformation = false;

            // add some basic references
            compilerParams.ReferencedAssemblies.Add( "mscorlib.dll");
            compilerParams.ReferencedAssemblies.Add( "System.dll");            
            compilerParams.ReferencedAssemblies.Add( "System.Data.dll" );
            compilerParams.ReferencedAssemblies.Add( "System.Drawing.dll" );
            compilerParams.ReferencedAssemblies.Add( "System.Xml.dll" );
            compilerParams.ReferencedAssemblies.Add( 
                  "System.Windows.Forms.dll" );

            if( Language == LanguageType.VB )
            {
                compilerParams.ReferencedAssemblies.Add( 
                      "Microsoft.VisualBasic.dll" );
            }

            //actually compile the code
            CompilerResults results = compiler.CompileAssemblyFromSource(
                    compilerParams, 
                    strRealSourceCode );

            //get a hold of the actual assembly that was generated
            Assembly generatedAssembly = results.CompiledAssembly;

            //return the assembly
            return generatedAssembly;
        }

CallEntry(Assembly...) is used for call entrypoint by reflection.

  
    // invoke the entry method
    // this method code is mainly from jconwell, 
    // see http://www.codeproject.com/dotnet/DotNetScript.asp
        private void CallEntry(Assembly assembly, string entryPoint)
        {
            try
            {
                //Use reflection to call the static Main function
                Module[] mods = assembly.GetModules(false);
                Type[] types = mods[0].GetTypes();

                foreach (Type type in types)
                {
                    MethodInfo mi = type.GetMethod(entryPoint, 
                            BindingFlags.Public | BindingFlags.NonPublic 

| BindingFlags.Static);  
                    if (mi != null)
                    {
                        if( mi.GetParameters().Length == 1 )  
                        {
                            if( 

mi.GetParameters()[0].ParameterType.IsArray )
                            {
                                string [] par = new string[1]; // if 

Main has string [] arguments
                                 mi.Invoke(null, par);
                            }
                        }
                        else
                        {
                            mi.Invoke(null, null);
                        }
                        return;
                    }
                }
            }
            catch (Exception ex)
            {
            }
        }

In the FormMain, make a new thread to make a CompileEngine instance and call Run.

         
  private void btnRun_Click(object sender, System.EventArgs e)
  {
   // we use a new thread to run it
   new Thread( new ThreadStart( RunTheProg ) ).Start();
  }

  private void RunTheProg()
  {
   string code = txtSource.Text.Trim();
   LanguageType language = chkIsCSharp.Checked ? 
      LanguageType.CSharp : LanguageType.VB;
   string entry = txtEntry.Text.Trim();

   if( code == "" ) return;
   if( entry == "" ) entry = "Main";

   CompileEngine engine = new CompileEngine( code, language, entry );

   engine.Run();
  }

Some things that can improve

In the PrepareRealSourceCode, it better to use regular expressions to find class name.

Acknowledgement

Thanks jconwell, VictorV, George Orwell, Eric Astor and other friends, they show me many excellent works on this topic, such as Dot Net Script, SnippetCompiler, Runtime Compilation.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

About the Author

dstang2000
Web Developer
China China
He is a professional developer. He use Java, C#, VB, C and many other languages.

Comments and Discussions

 
GeneralMy vote of 5 Pinmembermanoj kumar choubey23-Mar-12 1:22 
BugWarning! Fundamentally unavoidable memory leak! Don't use this code. Correct solution is known. PinmvpSAKryukov10-Feb-12 15:42 
GeneralMy vote of 1 PinmvpSAKryukov6-Feb-12 18:50 
GeneralRe: My vote of 1 Pinmembermr_neuromante18-Feb-12 3:42 
GeneralRe: My vote of 1 PinmvpSergey Alexandrovich Kryukov10-Aug-12 6:07 
GeneralMy vote of 5 [modified] PinmemberJigneshSE17-Jul-11 22:51 
Questioncan a web project use "ReferencedAssemblies.Add("customer.dll")" Pinmemberwlbkeats7-Dec-06 23:31 
NewsDynamic Code PinmemberPrimadi5-Jun-06 23:58 
GeneralRe: Dynamic Code PinmemberLiJinwei18-Jun-08 22:48 
GeneralRe: Dynamic Code PinmvpSAKryukov6-Feb-12 18:56 
GeneralMemory Leak Pinmembermackenb31-Jan-06 5:07 
GeneralRe: Memory Leak PinmvpSAKryukov6-Feb-12 18:38 
GeneralConfirm it (Re: Memory Leak) PinmvpSAKryukov6-Feb-12 18:55 
QuestionReferenceAssemblies.Add mine? PinmemberSkipSailors20-Jan-06 12:26 
AnswerRe: ReferenceAssemblies.Add mine? Pinmemberwlbkeats10-Dec-06 15:14 
QuestionHow to Create dll PinmemberAnu_K25-Dec-04 7:43 
AnswerRe: How to Create dll Pinmemberdstang200025-Dec-04 13:30 
GeneralRe: How to Create dll PinmemberAnu_K27-Dec-04 5:45 
GeneralRe: How to Create dll PinmemberAnu_K27-Dec-04 6:49 
GeneralGive credit where credit is due Pinmemberjconwell23-Mar-04 7:07 
GeneralRe: Give credit where credit is due PinsussAnonymous23-Mar-04 11:01 
GeneralRe: Give credit where credit is due Pinmemberjconwell23-Mar-04 11:04 
GeneralRe: Give credit where credit is due PinmemberMatthew Hazlett23-Mar-04 20:00 
Generalhn'Also the code is all wrong (Re: Give credit where credit is due) PinmvpSAKryukov6-Feb-12 19:07 
GeneralRe: Give credit where credit is due Pinmemberdstang200023-Mar-04 11:39 
GeneralRe: Give credit where credit is due [modified] PinmvpSAKryukov6-Feb-12 19:11 
GeneralSnippetCompiler PinmemberVictor Vogelpoel23-Mar-04 3:22 
GeneralRe: SnippetCompiler Pinmemberdstang200024-Mar-04 12:55 
GeneralRe: SnippetCompiler PinmemberEric Engler9-Feb-05 9:44 
GeneralRe: SnippetCompiler PinmemberVictor Vogelpoel9-Feb-05 9:57 
GeneralRe: SnippetCompiler PinmvpSAKryukov6-Feb-12 22:12 
GeneralDynamic Compilation PinmemberEric Astor23-Mar-04 1:01 
GeneralRe: Dynamic Compilation PinmemberMark Focas23-Mar-04 2:19 
GeneralRe: Dynamic Compilation Pinmemberdstang200024-Mar-04 12:52 
GeneralRe: Dynamic Compilation Pinmemberdstang200024-Mar-04 12:49 

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