Alternative compilers

Step-by-step tutorial

The following tutorial shows how to create an assembly which can be used by the script engine to provide access to additional CLR compilers. In this tutorial you will create CSSCodeProvider.dll, which will allow the script engine to execute C#, VB and JScript scripts depending on the script file extension.

By using any text editor (eg. Notepad.exe) create file CSSCodeProvider.cs, which contains the following code:

using System;
using System.IO;
using System.CodeDom.Compiler;
using Microsoft.JScript;

public class CSSCodeProvider
{
    static public ICodeCompiler CreateCompiler(string sourceFile)
    {
        string errMsg = "Alternative compiler for file extension "+Path.GetExtension(sourceFile)+
                    " cannot be created.";
        try
        {
            if (Path.GetExtension(sourceFile).ToLower() == ".cs")
                return (new Microsoft.CSharp.CSharpCodeProvider()).CreateCompiler();
            else if (Path.GetExtension(sourceFile).ToLower() == ".vb")
                return (new Microsoft.VisualBasic.VBCodeProvider()).CreateCompiler();
            else if (Path.GetExtension(sourceFile).ToLower() == ".js")
                return (new Microsoft.JScript.JScriptCodeProvider()).CreateCompiler();
        }
        catch (Exception ex)
        {
            throw new Exception(errMsg, ex);
        }
        throw new Exception(errMsg);
    }
}

Open command prompt. Make sure the current directory is the directory where CSSCodeProvider.cs located.
Execute the following command in command-prompt:
cscs /cd CSSCodeProvider

This command will create CSSCodeProvider.dll
Use Config console to instruct the script engine to use CSSCodeProvider.dll for creation of the alternative compiler.

By using any text editor (eg. Notepad.exe) create file hello.vb, which contains the following code:

' //css_reference System.dll;
' //css_reference System.Windows.Forms.dll;
Imports System
Imports System.Windows.Forms

Module Module1
    Sub Main()
        Console.WriteLine("Hello World! (VB)")
        MessageBox.Show("Hello World! (VB)")
    End Sub
End M

Execute the following command in command-prompt:
cscs hello.vb

Output

The script will print in command prompt "Hello World! (VB)". It will also display a corresponding MessageBox.

Code discussion

CSSCodeProvider can create and return an instance of either C#, VB or JScript compiler. Why these compilers? The answer is very simple: these three compilers are guaranteed to be available on any PC with .NET runtime installed. However, if on a particular PC the other CLR compilers are installed (C++, Delphi...), they can also be used with CS-Script. You would only need to modify the code of CSSCodeProvider.cs and compile it again.

In fact, it does not have to be an existing compiler. You can implement any compiler by yourself if you wish. Any compilers can be used with CS-Script as long as they support ICodeCompiler interface.

Note that System.dll and System.Windows.Forms.dll are referenced with //css_reference statement directly from the code. Because automatic assembly loading is not available for non-C# scripts (see Alternative Compilers for limitation details).

The same approach can be used to execute the J#/JScript "Hello world!" script. The command in command-prompt in this case will look as follows:

cscs hello.js

Where hello.js file contains the following code:

//css_reference System.dll;
//css_reference System.Windows.Forms.dll;
import System;
import System.Windows.Forms;

public class Class1 {
    public static function Main() {
        Console.WriteLine("Hello World! (JScript)");
            MessageBox.Show("Hello World! (JScript)")
    }
}

Alternative compilers

Step-by-step tutorial

Output

Code discussion

See Also