Creating a module-wide variable

[Larry]

Sorry if I'm not using the terminology correctly.

I already have several module-wide variables (created by Dim statements)
which enable information returned in one macro to be used in another
macro--a neat capability. But these variables only seem to work because
there already happens to be some public declarations at the top of the
module, like this:

Public Declare Sub Sleep Lib "kernel32" _
(ByVal dwMilliseconds As Long)

These public declarations have nothing to do with the Dim statements,
yet they enable them to work.

I want to learn how to set up a module-wide variable if there is not
already a Public declaration. In other words, if there is nothing at
the top of the module, and I want to create a module-wide Dim statement
there, how do I do that?

Thanks,
Larry

 

[Larry]

To clarify what I mean, here is the way the top of my Normal template
module now looks:

Public Declare Sub Sleep Lib "kernel32" _
(ByVal dwMilliseconds As Long)

' This Public Declare Function works with MoveMouse macro below.
Public Declare Function SetCursorPos Lib "user32" _
(ByVal x As Long, ByVal Y As Long) As Long

' These four variables are used by SetDocAsDoc and TwoDocsAltActivate.
Dim pFileName As String
Dim pDoc As Word.Document
Dim pFileName2 As String
Dim pDoc2 As Word.Document
Dim sFullName As String
Dim myReadOnlyDoc As String

If I remove the Public Declare statements, the declared variables cease
to work. So if there is no Public Declare statement in a module, how
would I declare the module-wide variable?

 

[Larry]

I found the answer in VB help. Instead of

Dim pFileName As String

I write

Public pFileName As String

 

[Jezebel]

Before you get carried away with this, be aware that it is very poor
programming practice. Do a Google on 'global variables' for any number of
discussions on why you should avoid them as much as possible, and what the
better alternatives are.

 

[Chuck]

Here's a link to an explanation of why global variables can cause problems
but also why they're not inherently a bad thing:

http://cpptips.hyperformix.com/cpptips/evil_globals

 

[Larry]

Well, to the extent I can follow his technical exposition, which is'nt
very much, this would seem to be a potential problem in a shared
environment. I don't see how it could be dangerous on an individual
user's version of Word.

I use these variables for a very simple purpose in just a few macros:
to re-activate or re-open a previously active document, or to go back
and forth instantly between any two documents without having to open the
Window menu or use the "NextWindow" command.

 

[Jezebel]

As Chuck says, they're not inherently bad -- just that if you rank the
causes of bugs in software, globals are right up there at or near the top of
the list. It's fine in a simple app with only a few functions -- the problem
comes as the app gets more complex. Even in a one-person situation this is
fraught. And since there are simpler and better ways of passing data between
functions, better to use good programming practices from the start.

 

[Larry]

Even in a
one-person situation this is fraught. And since there are simpler and
better ways of passing data between functions, better to use good
programming practices from the start.

Jezebel,

What are the better ways of doing it?

Here's an example of the way I use publicly declared variables. I've
declared these public variables at the top of the module.

Public pFileName As String
Public pDoc As Word.Document

When a document is active that I'm about to leave, but I want to be able
to return to that document instantly from any other document, I run a
macro that contains this code:

pFileName = ActiveDocument.FullName
Set pDoc = ActiveDocument

Then, when I'm in some other document and want to activate or open the
first document, I run this (I'm not showing the whole macro, which is a
lot bigger than this, just the key parts of it for the purpose of
discussion).

' If pDoc is an open document it is activated. If it is a closed
document it is opened.
For Each pDoc In Documents
If pDoc.FullName = pFileName Then
myFlag1 = True
Exit For
End If
Next
If myFlag1 = True Then
Documents(pFileName).Activate
Else
Documents.Open (pFileName)

This works very well. What would be a better (or safer?) way of doing
the same thing?

Larry

 

[Chuck]

Well, one way is to pass the file name as a parameter:

Sub FirstSub()

Dim pfilename As String
Dim pdoc As Word.Document

pfilename = ActiveDocument.FullName
Set pdoc = ActiveDocument

SecondSub pfilename, pdoc

End Sub

Sub SecondSub( _
ByVal pfilename As String, _
ByVal pdoc As Word.Document)

MsgBox pdoc.Name

End Sub