Using global variables in Access VB form modules...

[patjones]

Hi:

I have two forms, frmVerifyUser and frmVerifyNewPassword. In the VB module for both forms, at the very top, I try to set a global variable like

Public strNewPassword As String
Option Compare Database
Option Explicit

The problem is, when I set the variable in frmVerifyNewPassword, say

strNewPassword = Me!txtNewPasswordA

this assignment is not reflected in frmVerifyUser. What am I doing wrong here? Thank you...

[missinglinq]

You need to place the Public statement in a standard module to explicitly declare a variable as a public or global variable, and thus available throughout your database.

Linq ;0)>

[ADezii]

Hi:

I have two forms, frmVerifyUser and frmVerifyNewPassword. In the VB module for both forms, at the very top, I try to set a global variable like

Public strNewPassword As String
Option Compare Database
Option Explicit

The problem is, when I set the variable in frmVerifyNewPassword, say

strNewPassword = Me!txtNewPasswordA

this assignment is not reflected in frmVerifyUser. What am I doing wrong here? Thank you...

By Declaring a Variable as Public in a Form's Code Module, you are essentially making the Variable a Property of the Form. If strNewPassword is Declared and Initialized in Form1, you can reference it in Form2 as a Property of Form1, namely:

Forms!Form1.strNewPassword

NOTE: This is, however, not the acceptable Method.

[patjones]

By Declaring a Variable as Public in a Form's Code Module, you are essentially making the Variable a Property of the Form. If strNewPassword is Declared and Initialized in Form1, you can reference it in Form2 as a Property of Form1, namely:

Forms!Form1.strNewPassword

NOTE: This is, however, not the acceptable Method.

I take it then that Linq's method is the way to go...I'm not in front of the machine that has the database on it right now, but I'll try it when I get to work. Thank you!

[ADezii]

I take it then that Linq's method is the way to go...I'm not in front of the machine that has the database on it right now, but I'll try it when I get to work. Thank you!

I take it then that Linq's method is the way to go

Definately, stay with Linq's method. I was just illustrating some useless information. (LOL).

[patjones]

Definately, stay with Linq's method. I was just illustrating some useless information. (LOL).

Yup, putting it in a standard module works beautifully.

This is actually the second time that I ran into problems because I didn't know to use a standard module. The first time was when I defined my own function and kept it in the form's module (to be used by another form in the project). As soon as I put the function definition into a standard module, it worked great.

Are there any general guidelines for when to use a standard module?

Thanks!

[missinglinq]

Well, you really just defined it yourself! You store anything (functions, variables, constants, etc) in a standard module if you want it to be available from anywhere in your database.

One thing to remember, if you place a function in a new standard module, when it comes time to name the module, do not give it the same name as the function! This confuses the Access Gnomes something terrible!

Linq ;0)>

[patjones]

Well, you really just defined it yourself! You store anything (functions, variables, constants, etc) in a standard module if you want it to be available from anywhere in your database.

One thing to remember, if you place a function in a new standard module, when it comes time to name the module, do not give it the same name as the function! This confuses the Access Gnomes something terrible!

Linq ;0)>

Thanks so much for your help!

[ADezii]

Well, you really just defined it yourself! You store anything (functions, variables, constants, etc) in a standard module if you want it to be available from anywhere in your database.

One thing to remember, if you place a function in a new standard module, when it comes time to name the module, do not give it the same name as the function! This confuses the Access Gnomes something terrible!

Linq ;0)>

Besides those items already pointed out by Linq, here are a few more to remember. Do not feel bewildered because Variable Declaration and Scope is a very confusing Topic for newcomers.

1. First and foremost, keep the tightest Variable Scope as possible. If a Variable is only going to be used in the context of a Form's Module, declare it as Private within the Form's Module, not as Public in a Standard Code Module.
2. If a Variable is going to be used only within the context of a Standard Code Module, declare it as Private not Public, within the Standard Module.
3. Remember, a Variable declared as Private within a Standard Code Module can only be 'seen' from within that Module and no where else.
4. Avoid declaring Variables with the Static Keyword unless absolutely necessary - they incur a lot of overhead.
5. The same can be said for Public (Global) Variable but they are more dangerous since they can be modified from anywhere within your Application.
6. Avoid the tendency to declare Variables as Type Variant if applicable, you can run into problems and there is great overhead. Declare them as a specific Data Type or Object as in:
   

   Dim strTestString As String
   Private intCounter As Integer
   Public sngYearlyWage As Single
   Dim txtHours As TextBox

7. If you declare a Variable without any Data Type, it is a Variant by Default.
8. Declare Variables with the smallest Data type that will support the largest possible value. If you need a Variable to hold a person's age, you can declare it as a Byte (0 - 255) instead on an Integer or Long.
9. These are just a couple of things off the top of my head, there is much more on the Topic of Variable Declaration, Scope, and Usage but this will suffice for now.

[Kevin Wilcox]

Can I ride on the back of this slightly - is it important / possible to close public variables once finished with them, and if so, how? I have a lot of public strings and integers in my current project and apart from setting them to zero or "" once I've used them I don't do anything else.
Thanks

[ADezii]

Can I ride on the back of this slightly - is it important / possible to close public variables once finished with them, and if so, how? I have a lot of public strings and integers in my current project and apart from setting them to zero or "" once I've used them I don't do anything else.
Thanks

The problem is not so much in 'closing' them as it is their Scope, meaning there isn't anywhere that they can't be accessed in an Application. To the best of my knowledge, storage for Public Variables are dynamically assigned, so reinitializing them to 0 for Numerics or a Zero Length String for Strings may help. For Object Variables, always set them to Nothing (Set rstMyRecordset = Nothing) in order to release resources assigned to them. For large Public Arrays, you can always use the Erase Statement to re initializes the elements of fixed-size arrays and releases dynamic-array storage space. Besides these points, I'm not sure what else you can do.