Computer Programming Concepts and Visual Basic David I. Schneider

13.1 OLE
OLE, which stands for Object Linking and Embedding, is the evolving technology that allows
programmers to use Visual Basic to glue together applications like spreadsheets and word
processors. The three types of OLE are known as automation, linking, and embedding. With
automation, you control an application from outside. With linking and embedding, you bring
an application into your program. In this section, OLE is illustrated with Microsoft Excel and
Word. However, the programs and walkthroughs can be modified for other spreadsheet and
word processing software packages.
■ OLE AUTOMATION
The objects in the Visual Basic toolbox have both properties and methods, and Visual Basic
controls them by manipulating their properties and methods. In general, anything that can be
controlled by manipulating its properties and methods is called an object. In particular, an
Excel spreadsheet or a Word document can be specified as an OLE Automation object.
We have worked extensively with the data types String, Integer, and Single. There are
eight other data types, including one called Object. A variable that has been declared as an
Object variable can be assigned to refer to an OLE Automation object. The CreateObject
function is used to create an OLE Automation object and the Set statement is used to assign
the object to an object variable. For instance, the pair of statements
Dim objExcel As Object
Set objExcel = CreateObject(“Excel.sheet”)
creates an Excel spreadsheet object and assigns it to the Object variable objExcel. The pair of
statements
Dim objWord As Object
Set objWord = CreateObject(“Word.Basic”)
creates a Word document object and assigns it to the Object variable objWord. After the object
is no longer needed, a statement of the form
Set objVar = Nothing
should be executed to discontinue association of objVar with the specific object and release
all the resources associated with the previously referenced object.
An object is controlled by manipulating its properties and methods. For instance, the
statement
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