 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
VB Forum / Database Access / September 2008probably OT, architecture question OO references
Please redirect me if there's a better location for general architectural issues re: object oriented design vb6 and ado (or sqlite) I have a couple vb6 objects one that collects some data cBlockData.cls one that wraps database functionality IDBController.cls (either ado or sqlite implementations) some apps that would want to use cBlockData also need to put that info in a database for further processing so they would reference IDBController some apps would not need database some apps that use the database object would also need the cblockData obj but some would not currently it seems i have two options for passing info from one to other If i give the cBlockData object the responsibility to "Push info into " a database, I pass a db object into the blockData object in cBlockData Sub ToDatabase(oDbController as IDBController) .... but if i give the responsibility to the dbController to "Pull info from " a source object I pass the cBlockData obj to the cDB obj in cDbController.cls Sub ProcessBlockData(oBD as cBlockData) .... either way I couple two objects that sometimes belong together and sometimes don't have to both live in a given project. I suppose I could generalize cBlockData to IDataSource so db projects that don't need cBlockData wouldn't have to reference cBlockData(and it's long chain of other references that it depends on) the project would just have to contain a IDataSource object (even if it wasn't used) so there'd only be one unused reference instead of a long chain of unused references... then in cDbController.cls Sub ProcessBlockData(oBD as cBlockData) would become instead... Sub ProcessDataSource(oDS as IDataSource) ... .... either that or I create near duplicate objects that do and do not contain reference to the other kind of object (datasource or database wrapper) cBlockData-versionA ... with db cBlockData-versionB ...no db cDB-versionA ...uses blockData cDB-versionB ...uses some other source of info that seems like bad redundancy problem... it's monday and i havent finished my first pot of coffee yet so maybe all this is mudddled fuzzy thinking (as usual for me)??? thanks for any pointers mark > Please redirect me if there's a better location for general architectural > issues re: object oriented design "comp.object" probably comes as close as any in posting questions concerning "general architectural issues", but it is low traffic, and if you suggest using VB you will get no response or a lecture on the requirements for a language to be considered an OOPL. Other Forums are academic and you better know GOF, Fowler, Meyer, etc., forward and backwards, else again you will either be ignored, lectured, or told to get a good book. (Corollary to being told to RTFM. <g>) So give comp.object a shot, but leave VB out of your post. Most newsgroups (the useful ones anyway) are all dedicated to a specific language, platform, or design tool. AFAIK there isn't a highly populated one for classic VB. -ralph >> Please redirect me if there's a better location for general architectural >> issues re: object oriented design [quoted text clipped - 4 lines] > using VB you will get no response or a lecture on the requirements for a > language to be considered an OOPL. Yes, well, of course my inclusion of vb6 was merely a sleazy attempt to make it look slightly on topic so you would respond <g> with your usual OO wisdom... guess it was too transparent <g> mark > Please redirect me if there's a better location for general architectural > issues re: object oriented design [quoted text clipped - 4 lines] > one that wraps database functionality IDBController.cls (either ado or > sqlite implementations) IMHO - This is where is all goes wrong. When doing OOA/OOD I suggest you drop the terms "...Data" or "...Database" from your vocabulary. "Object-Oriented" analysis and design is the opposite from "Data-Centric" analysis and design. Those terms are filled with subjective connotation which can taint your solution. I suspect that is what has happened here. Objects that need to be stored likely need the services of IDBController. It is also easy to visualize why IDBController needs to be versioned (Specialization). But it is not clear why any object would need the services of a "Block of Data". Objects are methods(rules) AND data. I think you will find that cBlockData is an unnecessary abstraction, not a first-class object, and is not useful within your domain. But then I don't really know squat about your domain. -ralph > currently it seems i have two options for passing info from one to > other If i give the cBlockData object the responsibility to "Push info into > " a database, I pass a db object into the blockData object > in cBlockData > Sub ToDatabase(oDbController as IDBController) The good choice... > .... > but if i give the responsibility to the dbController to "Pull info > from " a source object I pass the cBlockData obj to the cDB obj > in cDbController.cls > Sub ProcessBlockData(oBD as cBlockData) > .... The bad choice. Asking all implementations of IDBController to know all about how to store any objects that might be passed to them is nutty. The place for code that knows how to store a particular kind of object is in the class definition of that object. > either way I couple two objects that sometimes belong together and > sometimes don't have to both live in a given project. Oh, my, that would be ... perfectly normal. Do all your VB apps use all the classes defined in VB? Particularly since the name IDBController implies it is an interface, and would carry virtually no baggage for an app that was only using cBlockData. Even if you only had the actual class, and it added 200K of unneeded code, well so what. >> currently it seems i have two options for passing info from one to >> other If i give the cBlockData object the responsibility to "Push info [quoted text clipped - 24 lines] > Oh, my, that would be ... perfectly normal. Do all your VB apps use all > the classes defined in VB? :-) good point... sometimes i just overthink things <g> > Particularly since the name IDBController implies it is an interface, and > would carry virtually no baggage for an app that was only using > cBlockData. Even if you only had the actual class, and it added 200K of > unneeded code, well so what. Thanks for the input. By sheer dumb luck that was the choice I had made and how it's structured. I just wasnt' sure if I was going in the right direction. ...the reason I had considered the other way around is I realized my current design has cBlockData.ToDatabase(oDbController) writing a record for each object in a collection.... where i have some hundreds of objects each writing a single record it makes more sense to collect them all and write once so I just need to resturcture my "supply side" 'instead of the current version... '................................................................ in Documents.ToDatabase (oDbController) For Each oDoc in oDocs oDoc.ToDatabase (oDbController) Next ...and... in Document.ToDatabase (oDbController) For Each oBlkData in oDoc oBlkData.ToDatabase(oDbController) Next '................................................................ I should do something like oDocuments.ToDatabase (oDbController) 'gather all data from all docs and send once to db AllDataFromAllDocuments.ToDatabase(oDbController) Thanks mark > ...the reason I had considered the other way around is I realized my > current design has [quoted text clipped - 3 lines] > makes more sense to collect them all and write once > so I just need to resturcture my "supply side" I think that should be the job of the DBController. It is quite common for the DB object to gather up the various records, then set about actually saving them in whatever way is suitable for the actual database. I would probably just have some method on the DBController called SaveChanges, which would indicate that I was done writing things, and now would be a good time to actually commit them to the database. Depends what DBController is actually doing, of course. |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.