OpenOffice.org Macros Explained - LibreOffice-NA.US

3.2.9. Declare variables with special types
You can use the keywords “As New” to define a variable as a known UNO struct. The word “struct” is an
abbreviated form of the word “structure” that is frequently used by computer programmers. A struct has one
or more data members, each of which may have different types. Structs are used to group associated data
together.
Option Compatible provides a new syntax to define variables of known and unknown types. A simple
example is declaring a variable of a specific type even if the type is not known to OOo Basic.
Option Compatible 'Supported in OOo 2.0
Sub Main
Dim oVar1 As Object
Dim oVar2 As MyType
Set oVar1 = New MyType 'Supported in OOo 2.0
Set oVar2 = New MyType 'Supported in OOo 2.0
Set oVar2 = New YourType 'Error, declared as MyType not YourType.
A new OLE object factory was introduced with OOo 2.0, which allows new types to be created. The new
functionality allows OOo Basic to manipulate Microsoft Word documents on Microsoft Windows operating
systems if Microsoft Office is also installed on the computer.
Sub Main
Dim W As Word.Application
Set W = New Word.Application
REM Dim W As New Word.Application 'This works in OOo 2.0
REM W = CreateObject("Word.Application") 'This works in OOo 2.0
W.Visible = True
End Sub
The use of CreateObject() does not rely on “Option Compatible” because this functionality is provided by
the new OLE object factory released with OOo 2.0.
3.2.10. Object variables
An Object is a complex data type that can contain more than a single piece of data. The code in Listing 16
shows an example of a complex data type. In OpenOffice.org, Object variables are intended to hold complex
data types created and defined by OOo Basic. When a variable of type Object is first declared, it contains the
special value Null, which indicates that no valid value is present.
Use the Variant type, not Object, to refer to OpenOffice.org internals. This is discussed later.
3.2.11. Variant variables
Variant variables are able to hold any data type. They take on the type of whatever is assigned to them. When
a variable of type Variant is first declared, it contains the special value Empty, which indicates that no value
has been assigned to the variable. A Variant may be assigned an integer in one statement and then assigned
text in the next. No typecasting occurs when assigning data to a Variant; it simply becomes the appropriate
type.
The chameleon-like behavior of Variant variables allows them to be used as any other variable type.
However, this flexibility comes with a cost: time. One final problem is that it isn’t always obvious what type
a Variant will become after making some assignments.
42