Global Variables (All)

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I’m doing some contract work on a DB that uses alot of globabal variables, which have gotten sort of unwieldy as the application has grown. Anyway, I’m in a situation where I need to get the value for a specific global variable, but which variable I need to look at depends on the value of control on a form. Actually, the global variable name is a concatenation of a base name plus the control value. Right now, we have to do something like a Select..Case(or IF statements) to get the value, something like this:

Select Case myControl
Case 1
temp = gintField1
Case 2
temp = gintField2
… etc.
End Select

Is there a way to reference a global variable using a string name such as you can do with a form, like in Forms(“myform”)? I tried to use Eval(), but Access didn’t seem to like that.

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Instead of using global variables, you might store values in a table, or in database properties. Both can be retrieved indirectly (concatenating strings to assemble a field name or a property name), and both have the added advantage that they don’t get cleared if an unhandled error occurs.

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Using the global variables was not my idea. It is a large and convoluted system, so I have to work with what is there. I’m just trying to make it a little easier.

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Using the global variables was not my idea. It is a large and convoluted system, so I have to work with what is there. I’m just trying to make it a little easier.

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Instead of using global variables, you might store values in a table, or in database properties. Both can be retrieved indirectly (concatenating strings to assemble a field name or a property name), and both have the added advantage that they don’t get cleared if an unhandled error occurs.

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Extremely long code fragment (over 6000 characters) moved to attachment – Mod

Hi Mark

Don’t know if this applies, the following is what I use for gv’s

May also want to check out ‘Scott Machado showed how in “Abstract Your Query Parameters” in the July 2001 issue of
‘ACCESS VB- SQL

HTH John

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John,

Thanks for the info. I’m going to look thru your attachment, plus I dug out my old copy of July 2001 edition of Access Advisor! I’ll let you know how it works out.

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John,

Thanks for the info. I’m going to look thru your attachment, plus I dug out my old copy of July 2001 edition of Access Advisor! I’ll let you know how it works out.

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Extremely long code fragment (over 6000 characters) moved to attachment – Mod

Hi Mark

Don’t know if this applies, the following is what I use for gv’s

May also want to check out ‘Scott Machado showed how in “Abstract Your Query Parameters” in the July 2001 issue of
‘ACCESS VB- SQL

HTH John

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Mark,

You might build a class or even just a standard function that would return the appropriate value based on an argument you passed in. A SELECT CASE statement could return the value from the appropriate global by using the value you passed to determine which variable value you needed. That is probably the fastest and dirtiest way to do it, particularly if you don’t really have any control over those globals.

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Yes, but that would still required use of a SELECT … CASE statement (or something like it) in the called function; which I may yet do. I was hoping something like this would work, but it won’t:

tem = eval(“gintField”& myfield)

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As far as I know, there is no way to do that, Mark. Variable names are literals, and over the years I’ve never found a way to do an end run on that. I think you’re going to have to settle for:

tem = GetGlobal(“gintField”& myfield)

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I think you are right. Well, it was worth a try!

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I think you are right. Well, it was worth a try!

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As far as I know, there is no way to do that, Mark. Variable names are literals, and over the years I’ve never found a way to do an end run on that. I think you’re going to have to settle for:

tem = GetGlobal(“gintField”& myfield)

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About the only other way you could do this would be use the VB CallByName function, which allows you to call a method or property of an object using a text string. CallByName uses some of the hidden OLE Interface methods used by VB for interaction with COM objects to resolve text string to an actual function address, thus it only works with objects. So you’d have to define an object (ie, class) for this purpose. Example: Assume there are these 3 “global” variables declared in a standard module:

Public gintGlobal As Integer
Public glngGlobal As Long
Public gstrGlobal As String

Create class module with following read-only properties:

Public Property Get Property1() As Variant
Property1 = gintGlobal
End Property

Public Property Get Property2() As Variant
Property2 = glngGlobal
End Property

Public Property Get Property3() As Variant
Property3 = gstrGlobal
End Property

If you want the properties to be read/write, include Let procedures:

Public Property Let Property1(ByVal NewValue As Variant)
gintGlobal = NewValue
End Property

(Etc for the other properties.) Example of using CallByName in standard module:

Public Sub TestCallByName()

Dim n As Long
Dim obj As Class1
Set obj = New Class1

gintGlobal = 1
glngGlobal = 111
gstrGlobal = "ABC"

For n = 1 To 3
Debug.Print CallByName(obj, "Property" & n, VbGet)
Next n

' If read/write, set values:
CallByName obj, "Property1", VbLet, 9
CallByName obj, "Property2", VbLet, 999
CallByName obj, "Property3", VbLet, "XYZ"

For n = 1 To 3
Debug.Print CallByName(obj, "Property" & n, VbGet)
Next n

Set obj = Nothing
End Sub

I don’t know if this would be worth the trouble, you’d have to create a Property procedure for each “global” variable. CallByName is not the most efficient method for retrieving values, as it requires the extra overhead of instantiating objects, and by definition uses late binding to call object properties and methods. But it does allow you to reference property/method as a text string; not aware of any way to directly reference the variable as a string.

HTH

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About the only other way you could do this would be use the VB CallByName function, which allows you to call a method or property of an object using a text string. CallByName uses some of the hidden OLE Interface methods used by VB for interaction with COM objects to resolve text string to an actual function address, thus it only works with objects. So you’d have to define an object (ie, class) for this purpose. Example: Assume there are these 3 “global” variables declared in a standard module:

Public gintGlobal As Integer
Public glngGlobal As Long
Public gstrGlobal As String

Create class module with following read-only properties:

Public Property Get Property1() As Variant
Property1 = gintGlobal
End Property

Public Property Get Property2() As Variant
Property2 = glngGlobal
End Property

Public Property Get Property3() As Variant
Property3 = gstrGlobal
End Property

If you want the properties to be read/write, include Let procedures:

Public Property Let Property1(ByVal NewValue As Variant)
gintGlobal = NewValue
End Property

(Etc for the other properties.) Example of using CallByName in standard module:

Public Sub TestCallByName()

Dim n As Long
Dim obj As Class1
Set obj = New Class1

gintGlobal = 1
glngGlobal = 111
gstrGlobal = "ABC"

For n = 1 To 3
Debug.Print CallByName(obj, "Property" & n, VbGet)
Next n

' If read/write, set values:
CallByName obj, "Property1", VbLet, 9
CallByName obj, "Property2", VbLet, 999
CallByName obj, "Property3", VbLet, "XYZ"

For n = 1 To 3
Debug.Print CallByName(obj, "Property" & n, VbGet)
Next n

Set obj = Nothing
End Sub

I don’t know if this would be worth the trouble, you’d have to create a Property procedure for each “global” variable. CallByName is not the most efficient method for retrieving values, as it requires the extra overhead of instantiating objects, and by definition uses late binding to call object properties and methods. But it does allow you to reference property/method as a text string; not aware of any way to directly reference the variable as a string.

HTH

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Yes, but that would still required use of a SELECT … CASE statement (or something like it) in the called function; which I may yet do. I was hoping something like this would work, but it won’t:

tem = eval(“gintField”& myfield)

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Mark,

You might build a class or even just a standard function that would return the appropriate value based on an argument you passed in. A SELECT CASE statement could return the value from the appropriate global by using the value you passed to determine which variable value you needed. That is probably the fastest and dirtiest way to do it, particularly if you don’t really have any control over those globals.

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If the only thing that’s going to vary at runtime is the final number, couldn’t the gintField variables simply be combined into a single global array?

temp = gaField(myControl)

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>>If the only thing that’s going to vary at runtime is the final number, couldn’t the gintField variables simply be combined into a single global array?<<

No. I can't change the names of the global variables. Again, this question was not about how to change the system, but rather how to deal with the variables as they are.

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>>If the only thing that’s going to vary at runtime is the final number, couldn’t the gintField variables simply be combined into a single global array?<<

No. I can't change the names of the global variables. Again, this question was not about how to change the system, but rather how to deal with the variables as they are.

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If the only thing that’s going to vary at runtime is the final number, couldn’t the gintField variables simply be combined into a single global array?

temp = gaField(myControl)

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