Tom Bolton
tom.bolton at donnslaw.co.uk
Tue May 17 10:55:12 CDT 2005
Yip, well said! I see both sides of the argument, especially as an ASP developer by trade - we all know the industry opinion on using app-wides declared in the global.asa but we all also know we use them! I feel as though I'm committing some terrible evil every time I'm forced into a corner and have to publicly declare something, either in ASP or VB. Eventually there has to be a payoff between the sort of code in the example below and RAD - surely a developer who can use globals and still write efficient, robust code is still a good developer? It is possible... Tom -----Original Message----- From: DWUTKA at marlow.com [mailto:DWUTKA at marlow.com] Sent: 17-May-2005 16:32 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. By having a private variable returned by a public function, any function that needs the information can get it but cannot modify it. -- AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com -- AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com -- AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com -------------- next part -------------- The contents of this message and any attachments are the property of Donns Solicitors and are intended for the confidential use of the named recipient only. They may be legally privileged and should not be communicated to, or relied upon, by any other party without our written consent. 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