Word Document Properties

Figure 6-5:
Use the
Locals
window to
see visible
variables.
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Chapter 6: Trapping Errors and Squashing Bugs
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Two objects appear next in the list. Normally, just the object name appears in
the list. Click the plus sign next to the name, and you see the object proper-
ties and their values. Notice that the 
MyDrive.AvailableSpace
property
matches the 
FreeSpace
value because I stopped the program immediately
after the drive space assignment. (See the earlier “Recovering from an error”
section for details.)
Objects can contain other objects. 
MyDrive
is a 
Drive
object that contains a
RootFolder
object. Notice the plus sign next to 
RootFolder
in Figure 6-5.
Click this plus sign, and the Locals window shows the contents of the second
object. You can continue looking through a hierarchy of objects until you
reach the last one contained within the original object.
The Locals window is also handy for playing what-if scenarios with your pro-
gram. The 
DriveTest
program always fails because the check value is too
high. You can double-click the Value field of the 
FreeSpace
entry to change
its value to 1,000,000,001. The check passes now because 
FreeSpace
is one
more than the check value. Try this test; the program exits without error.
Using the Watches Window
The Watches window works similarly to the Locals window, but has a differ-
ent purpose. The Locals window shows variables in their raw format and
only the variables that you can see locally. You might want to see other vari-
ables, or you can use a function to change a variable before viewing it. The
Watches window helps you perform these kinds of tasks, but it requires a
little more work to use. You can display the Watches window by clicking the
Watch Window button on the toolbar. Figure 6-6 shows a typical example of
the Watches window.
Notice that this window adds a Context field. This field tells you where a vari-
able is defined. Because you can use variables from any location, knowing
where they come from is important.