Questions on using global variables

  • Thread starter Thread starter Gary Schuldt
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Gary Schuldt

I haven't (successfully) used global variables yet, so I have a couple of
questions. The general context here is a multi-user environment with user
profiles (quite rudimentary at this point in the development).

1. Declaring

I assume I at least declare Public pubVar As . . . outside of any particular
module in a Modules object (container).

Q1: Do I also declare it using the same syntax in every module in which I
want to refer to it?

2. Profile parameters

I have a few users already. I'd like to put their profile parameters
(fields) into a tblUsers.

When a user logs on, I could store their UserID in a Public pubIntUserID.
Then, whenever I wanted to use a particular User.field value, I could look
it up in the tblUsers.

Or, I could copy ALL the parameters for that UserID into Public variables
and use them that way in the modules that need them.

Q2: Any comments on which is preferable from a best practice point of view?

Q3: Any other things to watch out for in this approach?

Thanks in advance.

Gary
 
Answers/comments inline....

--
Ken Snell
<MS ACCESS MVP>

Gary Schuldt said:
I haven't (successfully) used global variables yet, so I have a couple of
questions. The general context here is a multi-user environment with user
profiles (quite rudimentary at this point in the development).

1. Declaring

I assume I at least declare Public pubVar As . . . outside of any particular
module in a Modules object (container).

Q1: Do I also declare it using the same syntax in every module in which I
want to refer to it?
Click to expand...

No, you would declare it only once in the public module. If you declare it
again inside another module, it'll become a local variable within that
module with different values.

2. Profile parameters

I have a few users already. I'd like to put their profile parameters
(fields) into a tblUsers.

When a user logs on, I could store their UserID in a Public pubIntUserID.
Then, whenever I wanted to use a particular User.field value, I could look
it up in the tblUsers.

Or, I could copy ALL the parameters for that UserID into Public variables
and use them that way in the modules that need them.

Q2: Any comments on which is preferable from a best practice point of
Click to expand...
view?

DLookup function to get the values from a table would be preferable in my
opinion. Global variables will lose their values if there is an unhandled
error while the code runs. As such, I find it preferable to avoid their use
and instead use hidden textboxes on forms or reports, or use tables, for
storing long-term variables such as you envision. They are not prone to
"loss" in these situations.

Q3: Any other things to watch out for in this approach?
Click to expand...

See above. I usually use global variables in ACCESS strictly within a form
module and usually for short-term things, after I have thoroughly
reviewed/tested my code to be sure that all possible errors will be handled
by error-handling code. Also, if someone else will make changes to your code
(or even you for example) and you/that person don't realize that a variable
name is already being used as a global variable, then you could get
confusion if the variable is reused in another module. If you do use global
variables, name them in nonobvious ways (for example, I often put glb or x
or some other prefix in front of my "normal" variable naming convention:
strPersonName becomes glbstrPersonNamex or such) so that it's less likely
this would occur.

Note also that global constants do not suffer this "loss" behavior with
errors ... I use them frequently in my code.
 
Ken,

thanks for the useful insight into global variables. I think your message
answers all the questions I have for now!

Thanks.

Gary
 
I haven't (successfully) used global variables yet, so I have a couple of
questions. The general context here is a multi-user environment with user
profiles (quite rudimentary at this point in the development).

1. Declaring

I assume I at least declare Public pubVar As . . . outside of any particular
module in a Modules object (container).

Q1: Do I also declare it using the same syntax in every module in which I
want to refer to it?

2. Profile parameters

I have a few users already. I'd like to put their profile parameters
(fields) into a tblUsers.

When a user logs on, I could store their UserID in a Public pubIntUserID.
Then, whenever I wanted to use a particular User.field value, I could look
it up in the tblUsers.

Or, I could copy ALL the parameters for that UserID into Public variables
and use them that way in the modules that need them.

Q2: Any comments on which is preferable from a best practice point of view?

Q3: Any other things to watch out for in this approach?

Thanks in advance.

Gary
Click to expand...
--------------------
Hi Gary,

You need only define the global variable and assign a value once. Typically
you would have an autoexec macro with a Runcode action to initialise the
global variable. From then on, the global variable is available in any or
all modules.

Hope this helps,
 
Thanks, Eric, that helps.

Gary

Eric Cárdenas said:
--------------------
Hi Gary,

You need only define the global variable and assign a value once. Typically
you would have an autoexec macro with a Runcode action to initialise the
global variable. From then on, the global variable is available in any or
all modules.

Hope this helps,

--
Eric Cárdenas
Senior support professional

This posting is provided "AS IS" with no warranties, and confers no rights.
Click to expand...
 
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