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Add a Scripting Engine to Your Application

Add a Scripting Engine to Your Application

It’s easy to add scripting functionality to your VB project, especially if you have been developing through classes all along. The more classes you program, the more objects you can expose to your script language. You can use both VBScript and JScript as the basis for your scripting engine.

First, download the Microsoft Script Control from MSDN. Install the control according to the instructions provided. You might need to register the control manually (run regsvr32 on it). The footprint on this control is low; the whole download including help is only 243K. Next, create a script file with a text editor such as Notepad:

 Sub Main()	MsgBox "Hello, world"End Sub

Save it as c: emp.txt and add this code to your application:

 Private Sub Command1_Click()	Dim iFileNum As Long	Dim sFileBuffer As String	Dim sTemp As String	iFileNum = FreeFile()	Open "c:	emp.txt" For Input As #iFileNum		Do While Not EOF(iFileNum)			Line Input #iFileNum, sTemp			sFileBuffer = sFileBuffer & sTemp & _				vbCrLf		Loop	Close #iFileNum	ScriptControl1.Reset	ScriptControl1.AddCode (sFileBuffer)	ScriptControl1.Run "Main"End sub

You have now successfully implemented a scripting engine. You can expose objects in your application like this:

 Private Sub Command1_Click()	Dim objMyClass As New MyClassNameHere	With dlgCommon		.ShowOpen		sFileName = .FileName	End With	iFileNum = FreeFile()	Open sFileName For Input As #iFileNum		While Not EOF(iFileNum)			Line Input #iFileNum, sTemp			sFileBuffer = sFileBuffer & sTemp & vbCrLf		Wend	Close #iFileNum	ScriptControl1.Reset	ScriptControl1.AddObject "Database", objMyClass	ScriptControl1.AddCode (sFileBuffer)	ScriptControl1.Run "Main"End sub

You can even try code such as this to give ad hoc capabilities to an application:

 ScriptControl1.ExecuteStatement "x = 100"MsgBox ScriptControl1.Eval("x = 100")  ' TrueMsgBox ScriptControl1.Eval("x = 100/2")  ' False
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