[AccessD] Global Variable

Roz Clarke roz.clarke at donnslaw.co.uk
Wed May 18 08:18:24 CDT 2005


Everyone

I'm afraid this thread is getting out of hand - too much heat and not much
light. If you wish to continue the discussion please address one another
off-list.

Thanks

Roz (in moderator mode)

-----Original Message-----
From: Tom Bolton [mailto:tom.bolton at donnslaw.co.uk] 
Sent: 18 May 2005 14:00
To: 'Access Developers discussion and problem solving'
Subject: RE: [AccessD] Global Variable


So if you don't use globals, another developer will never mess around with
your code and cause it to function incorrectly?

Sorry, I'm not being facetious, I honestly think (and know from experience)
that when other developers (inc. myself) tinker with someone else's code,
things can and will go wrong regardless.

I'm following this with some interest and can actually see both sides...

Tom



-----Original Message-----
From: Scott Marcus [mailto:marcus at tsstech.com] 
Sent: 18 May 2005 13:41
To: Access Developers discussion and problem solving
Subject: RE: [AccessD] Global Variable

<< Declaring a variables an Integer IS bad practice.  It is bad practice
because even if you think a variable will never go over 32k, or below -32k,
it can, and probably will.

Question: So when will the following declaration exceed the 32k, -32k limit?

Dim intFamilyMembers as integer 'Number of immediate family members

Answer: When you declare the variable as a Public (global) variable, then
some other function written by some other developer changes its intended use
causing the original function to possibly work incorrectly.

Scott Marcus

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of DWUTKA at marlow.com
Sent: Tuesday, May 17, 2005 7:05 PM
To: accessd at databaseadvisors.com
Subject: RE: [AccessD] Global Variable

I guess I'm not seeing the same definition from John, though it was closer
in the last few posts.  Yes, 'bad practice' sends me into a tail spin, when
there is no reason for calling something bad practice.  Declaring a variable
as an Integer IS bad practice.  It is bad practice because even if you think
a variable will never go over 32k, or below -32k, it can, and probably will.
But more importantly, an Integer is a 16 bit variable, and it takes longer
to process an Integer then it does a Long Integer, on a 32 bit system. The
first reason is a philosophy.  The second reason is a FACT!

I have yet to hear a fact, as to why Globals are 'bad practice'.  What gets
my goat, though, is that this is a forum where developers of all skill level
meet.  If opinions are given as facts, developers who are learning something
new could be hampered by prejudice.  Ever run into an IT shop that refuses
to allow applications to be developed in Access, because 'it's not a
database', or 'it's not secure', or something else, that is just ignorance
repeated through 'tribal knowledge'?  (There is also usually power
involved...and IT shop has more power and control involved when something is
on a server side db.)  That's why I rail on this stuff, because invalid
tribal knowledge can be dangerous!

Drew

-----Original Message-----
From: Francisco Tapia [mailto:fhtapia at gmail.com]
Sent: Tuesday, May 17, 2005 5:44 PM
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] Global Variable


How right you are Charlotte!, This whole thread I hear the same definition 
from both John and Drew... One should take caution while using global 
(public variables), Except John said the immortal words of "Bad Programming 
Practice" wich for some reason seems to send Drew in a spin. He repeats 
John's definition but just omit's the "Bad Programming Practice" phrase.

Drew, there are a lot of things people can do w/ code, hundres of variations

and they can all arrive to the same final solution, however I do believe

that there are certain procedures deemed as bad programming practice as a 
principal. And rules are made to be broken. I've been working so much more 
in Sql Server now-a-days and some of the common things that are bad 
programming practice there are such taboo tid-bits like cursors and dynamic 
sql. This same type of argument seems to ignite holly wars between 
bounder-like devils and unbouder-like crusaders ;). It really is amazing to 
find the various ways to accomplish something. Public (global) variables are

yet another tool in our quest for solutions. John's point of view (if i'm 
interpreting it correctly) is that in general try not to treat 
Public(global) variables like a hammer...

otherwise everything will just look like a nail.

and speaking of .. this whole thread has been beaten to death Or don't you 
think so?


On 5/17/05, Charlotte Foust <cfoust at infostatsystems.com> wrote:
> 
> LOL. And for an encore, should I demonstrate proving ANOTHER negative 
> like why you didn't prove anything??? <g>
> 
> Charlotte Foust
> 
> 
> -----Original Message-----
> From: DWUTKA at marlow.com [mailto:DWUTKA at marlow.com]
> Sent: Tuesday, May 17, 2005 1:53 PM
> To: accessd at databaseadvisors.com
> Subject: RE: [AccessD] Global Variable
> 
> LOL. Well Charlotte. Give me a valid reason. I think I have proven all 
> of the current ones incorrect. If you don't think so, which ones?
> 
> Drew
> 
> -----Original Message-----
> From: Charlotte Foust [mailto:cfoust at infostatsystems.com]
> Sent: Tuesday, May 17, 2005 3:34 PM
> To: Access Developers discussion and problem solving
> Subject: RE: [AccessD] Global Variable
> 
> Give it up, John. When Drew decides no one elses arguments make any 
> sense, there's no reasoning with him. ;->
> 
> Charlotte Foust
> 
> -----Original Message-----
> From: John W. Colby [mailto:jwcolby at colbyconsulting.com]
> Sent: Tuesday, May 17, 2005 1:06 PM
> To: 'Access Developers discussion and problem solving'
> Subject: RE: [AccessD] Global Variable
> 
> ROTFL.
> 
> John W. Colby
> www.ColbyConsulting.com <http://www.ColbyConsulting.com>
> 
> Contribute your unused CPU cycles to a good cause: 
> http://folding.stanford.edu/
> 
> -----Original Message-----
> From: accessd-bounces at databaseadvisors.com
> [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of 
> DWUTKA at marlow.com
> Sent: Tuesday, May 17, 2005 3:58 PM
> To: accessd at databaseadvisors.com
> Subject: RE: [AccessD] Global Variable
> 
> You have said that using Globals is bad practice, which it is not.
That
> is my argument. The misuse is. 'Getting carried away with'...well, 
> that's an iffy statement, because you have to judge what is 'getting 
> carried away with' and what is not.
> 
> Drew
> 
> -----Original Message-----
> From: John W. Colby [mailto:jwcolby at colbyconsulting.com]
> Sent: Tuesday, May 17, 2005 2:02 PM
> To: 'Access Developers discussion and problem solving'
> Subject: RE: [AccessD] Global Variable
> 
> Would "getting carried away with globals" be considered misuse of 
> globals? If you look back to the first post you see that is what I 
> warned against. Notice I did NOT tell him that in his particular case
he
> should not use a global.
> 
> YOU have built an argument for your own amusement, but in the end it
has
> enabled us to discuss the issue which is a good thing.
> 
> John W. Colby
> www.ColbyConsulting.com <http://www.ColbyConsulting.com>
> 
> Contribute your unused CPU cycles to a good cause: 
> http://folding.stanford.edu/
> 
> -----Original Message-----
> From: accessd-bounces at databaseadvisors.com
> [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of 
> DWUTKA at marlow.com
> Sent: Tuesday, May 17, 2005 2:40 PM
> To: accessd at databaseadvisors.com
> Subject: RE: [AccessD] Global Variable
> 
> Ah. There's the issue. 'If a global doesn't need to be SET by project 
> wide code'. Okay. Now, that I will back down on. I personally don't 
> have an issue with setting it one place, and using it other places. No 
> problem there. But what if you are constantly using (reading and
> writing) it from many places in your project. Does a Global Variable 
> fit the model? Of course! Honestly, I use classes too, and will make 
> read only properties 'read only'.
> 
> Drew
> 
> P.S.-- Still doesn't make Globals bad practice, only misuse of 
> globals...which is still my position.
> 
> -----Original Message-----
> From: John W. Colby [mailto:jwcolby at colbyconsulting.com]
> Sent: Tuesday, May 17, 2005 11:52 AM
> To: 'Access Developers discussion and problem solving'
> Subject: RE: [AccessD] Global Variable
> 
> I understand completely Drew. In order to not use globals you have to 
> THINK and you are too busy typing to do that.
> 
> Correct me if I am wrong, but nowhere did I advocate any code like you 
> mentioned. Can you show me where in my email I advocated that? What I 
> said was that if a global doesn't need to be SET by project wide code 
> then itdoesn't need to be global.
> 
> I have seen in your previous posts where you mention saving
keystrokes.
> Understand that I am NOT a data entry person. My job is to design well 
> engineered systems. If that means more keystrokes, so be it.
> 
> John W. Colby
> www.ColbyConsulting.com <http://www.ColbyConsulting.com>
> 
> Contribute your unused CPU cycles to a good cause: 
> http://folding.stanford.edu/
> 
> -----Original Message-----
> From: accessd-bounces at databaseadvisors.com
> [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of 
> DWUTKA at marlow.com
> Sent: Tuesday, May 17, 2005 11:32 AM
> To: accessd at databaseadvisors.com
> Subject: RE: [AccessD] Global Variable
> 
> Tighter? If I looked at code like this:
> 
> Dim MyModuleLevelString as String
> Private Function SetModuleLevelString(strValueToSet As String) 
> MyModuleLevelString=strValueToSet End Function
> 
> I would think the developer was getting paid by the key stroke.....not 
> that it was 'tight code'.
> 
> Drew
> 
> -----Original Message-----
> From: John W. Colby [mailto:jwcolby at colbyconsulting.com]
> Sent: Tuesday, May 17, 2005 6:59 AM
> To: 'Access Developers discussion and problem solving'
> Subject: RE: [AccessD] Global Variable
> 
> Gustav,
> 
> This is nothing new, and not something I take credit for figuring out. 
> It is not uncommon when you work with classes to have methods set the 
> values of and return the values from class properties. In fact with 
> classes you have syntax constructs specifically for this - property 
> get/set/let. You can, if you wish, dim a variable public in the class 
> header and then it is just read / write to anyone with a pointer to
the
> class. Or you use a property get and or set/let in whatever
combination
> you need. A read-only value has only a property get. A Write-only has 
> only a property set (not very common) and a read / write has a
property
> get and property let/set.
> 
> The objective is simply to control how the variable is read/written. 
> Since the variable is dimensioned private to the module (or class),
only
> a function in the module or class can set the value, and only a
function
> in the module or class can return the value. To make a property "read 
> only", create only a function that returns the value, but do not build
a
> function that sets the value. Then only the class or module itself can 
> set the variable.
> 
> For example as the module initializes, perhaps some value is pulled
from
> a table and written into the variable. Then a function returns the 
> value to any process that needs the value. Or perhaps the value is 
> calculated by some math transformation using other values in other 
> variables. The other variables are set by processes, but in order to 
> read out the value, a function either returns the variable directly or 
> returns the value of the mathematical transformation using the values
in
> the other variables.
> 
> This is not new stuff, I did not invent it, but it is commonly used to 
> "replace" global variables such that the CONCEPT of a global variable 
> exists (can be seen from anywhere) but still protects the variable
from
> being written when it shouldn't be or by processes that should not be 
> able to write to the variable.
> 
> And yes, it is more work. It is just one of those things that you do
or
> your don't. If you accept the practice, then you start thinking about 
> protecting variables, using variable scope, and using functions to set
/
> return values where appropriate. It becomes habit and your code
becomes
> a little bit tighter.
> 
> John W. Colby
> www.ColbyConsulting.com <http://www.ColbyConsulting.com>
> 
> Contribute your unused CPU cycles to a good cause: 
> http://folding.stanford.edu/
> 
> -----Original Message-----
> From: accessd-bounces at databaseadvisors.com
> [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Gustav
Brock
> Sent: Tuesday, May 17, 2005 6:30 AM
> To: accessd at databaseadvisors.com
> Subject: RE: [AccessD] Global Variable
> 
> Hi John
> 
> Well, here we have full control on where functions put their nasty 
> fingers.
> 
> I haven't managed yet to build self generating code; to some this
would
> indicate a brave new world, to some it would be a nightmare -
functions
> creeping around and attacking our globals and eating our children... 
> gosh. But worse, they would soon learn how to take advantage of your 
> functions to change those "private variables"! Be prepared.
> 
> /gustav
> 
> >>> jwcolby at colbyconsulting.com 05/16 10:58 pm >>>
> 
> .. Making this a global allows functions
> that have no business setting these variables to change them. By
having
> a private variable returned by a public function, any function that 
> needs the information can get it but cannot modify it.
> 
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