Professional IronPython

PERfORMINg LATE BINDINg uSINg MARSHAL.gETACTIvEOBjECT()
Sometimes you need to interact with an application that’s already running. In this case, you don’t 
want to create a new object; you want to gain access to an existing object. The technique used to 
perform this type of late binding is to call 
Marshal.GetActiveObject()
with the type of object you 
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CHAPTER 9
InteractIng wIth cOM Objects
want to access. Typically, you use this technique with application objects, such as a running copy of 
Word. Listing 9-5 shows an example of how to use 
Marshal.GetActiveObject()
to gain access to 
a running Word application.
LISTINg 9-5: 
 Working with a running copy of Word
# Import only the required classes from System.
from System.Runtime.InteropServices import Marshal
# Obtain a pointer to the running Word application. 
# Word must be running or this call will fail.
WordObj = Marshal.GetActiveObject(‘Word.Application’)
# Add a new document to the running copy of Word.
MyDoc = WordObj.Documents.Add()
# Get the Application object.
App = MyDoc.Application
# Type some text in the document.
App.Selection.TypeText(‘Hello World’)
App.Selection.TypeParagraph()
App.Selection.TypeText(‘Goodbye!’)
The 
import
statement differs from normal in this example. Notice that you can drill down into 
the namespace or class you want, and then import just the class you need. In this case, the example 
requires only the 
Marshal
class from 
System.Runtime.InteropServices
.
The first step is to get the running application. You must have a copy of Word running for
this step to work; otherwise, you get an error. The call to 
Marshal.GetActiveObject()
with
Word.Application
returns a Word object, 
WordObj
. This object is the same object you get when 
working with Visual Basic for Applications (VBA). In fact, if you can do it with VBA, you can do
it with IronPython.
After gaining access to Word, the application adds a new document using 
WordObj.Documents.Add()
. 
It then creates an 
Application
object, 
App
. Using the 
App.Selection.TypeText()
method, the 
application types some text into Word, as shown in Figure 9-16. Of course, you can perform any task 
required — the example does something simple for demonstration purposes.
fIguRE 9-16: 
You can control Word using IronPython as easily as you can using VBA.
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