Scott Marcus
marcus at tsstech.com
Wed May 18 07:25:44 CDT 2005
Drew, There are many things in life that are bad practice. Bad practice does not make something wrong; it's just not the wisest choice. Same goes for programming. It seems that you make arguments for bad practice on things like integer declaration (which one could argue as valid just like you did for globals), without reason, and you raise hell because others did the same thing about globals. Then when given valid reasons, you try twisting the reason into something that was not said. Case in point, no variable ever changes auto magically, but you make it sound like JC is saying that. What he is saying is that any developer using the code (and face it, some of us are on teams with multiple programmers) can dink with the variable, most of the time by accident, outside its intended use. Most of the issues I've seen where globals bring to light why they are bad practice involve a second developer storing a value that was never intended to be placed in the variable that causes another function (seemingly unrelated), written by another developer, to crash and burn (not an error per se but definitely not a value that the function would expect)(I've seen this one before, a global called sex that contained the invalid value of 'neutered male'). This is just one facet of spaghetti code. Is spaghetti code bad practice? But if the program works and is bug free... It's still not a valid argument. There are valid uses of lots of programming things that in general are bad practice. This does not mean you should never use them. I would much rather tell a new developer that a global is bad practice and then later show them an instance where it is needed, than not pointing out the bad practice and then helping them fix the mess they got themselves into. Maybe you take offense to the bad practice comment because deep down you know you use global variables too much. Or maybe you just like to debate for the sake of debating. 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 6:15 PM To: accessd at databaseadvisors.com Subject: RE: [AccessD] Global Variable Not sure what you mean. Are you defending the claim that Global Variables are 'bad practice' or not? If you are, why are they bad practice? Drew -----Original Message----- From: Charlotte Foust [mailto:cfoust at infostatsystems.com] Sent: Tuesday, May 17, 2005 4:39 PM To: Access Developers discussion and problem solving Subject: RE: [AccessD] Global Variable 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 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 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 it doesn'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 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 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. 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