BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Design Questions First Steps          BorlandTalk.com Forum Index -> Delphi OO design View previous topic :: View next topic   Author Message diktyo Guest Posted: Wed May 11, 2005 6:19 pm    Post subject: Design Questions First Steps First steps in OO design (literlly crawling through MVP, Iterators etc). Trying to design some simple Business Objects (not even accustomed to the notation ...) type TCity = class(TObject) fCityID : integer; fCityDesc : string; TCustomer = class(TObject) fCustID : integer; fCustName : string; f................... fCityID : integer; fCityName : string ;//<======= should I put it here ???? CITY is kind of look-up object. In DB Normalization theory I should NOT put CityDesc within Customer (record). Is there any BENEFIT (only benefits please) so as to put it in TCustomer ? Thanks Petros PS. I am (trying to) develop a simple application for an association I am member to (no fees involved) and I have "plenty" of time (till summer end), so I decided to give it a try both ways , the old RAD way and the "new to me" OO way. I also post to Database groups, but for the "old" way" Back to top Peter Morris [Droopy eyes Guest Posted: Wed May 11, 2005 10:21 pm    Post subject: Re: Design Questions First Steps Quote: fCityID : integer; fCityName : string ;//<======= should I put it here ???? You should have CityID or CityName there, you should only have City: TCity; You can get the ID from the City object itself if you need to. If you are trying various approaches, you should try ECO. -- Pete ==== ECO Modeler, Audio compression components, DIB graphics controls, FastStrings http://www.droopyeyes.com Read or write articles on just about anything http://www.HowToDoThings.com My blog http://blogs.slcdug.org/petermorris/ Back to top Joanna Carter (TeamB) Guest Posted: Wed May 11, 2005 10:34 pm    Post subject: Re: Design Questions First Steps "diktyo" <diktyo (AT) mail (DOT) gr> a ecrit dans le message de news: [email]42824caf (AT) newsgroups (DOT) borland.com[/email]... Quote: type TCity = class(TObject) fCityID : integer; fCityDesc : string; Of course you should never have published fields like this :-) You should really not use the class name to prepend fields or properties either : TCity = class private fID: Integer; fDescription: string; ... public property ID ... property Description ... ... end; TCustomer = class private fID: Integer; fName: string; f................... fCity: TCity; public property ... end; Quote: fCityName : string ;//<======= should I put it here ???? You should not have anything to do with the City, apart from a TCity object, inside the Customer class. Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker Back to top diktyo Guest Posted: Thu May 12, 2005 9:05 am    Post subject: Re: Design Questions First Steps Quote: You should not have anything to do with the City, apart from a TCity object, inside the Customer class. Joanna It's so obvious when someone else tells you how to do it !!! Joanna, Peter thanks, but I think I need a much stronger brainwash to get rid of old habits (design database schema first etc.) Can't teach an old dog new tricks. Petros Back to top Joanna Carter (TeamB) Guest Posted: Thu May 12, 2005 10:09 am    Post subject: Re: Design Questions First Steps "diktyo" <diktyo (AT) mail (DOT) gr> a écrit dans le message de news: [email]42831c6d (AT) newsgroups (DOT) borland.com[/email]... Quote: Joanna, Peter thanks, but I think I need a much stronger brainwash to get rid of old habits (design database schema first etc.) Yes, it's a common problem :-) Don't forget to look up things like how to manage aggregation vs. composition : Aggregation means just having a reference to an object like your City example. Composition means ensuring the that a containing class is totally responsible for the items it contains. e.g. SalesOrder contains SalesOrderLine items. In this case, you would expect a database to have a reference to the SalesOrder in each of the SalesOrderLines. But this is not how you design classes; you should have a read only list property inside the SalesOrder class and only be able to add new lines by addressing an AddLine method in the SalesOrder class. Not aiming to confuse you; just making sure you don't let this one slip by ) Quote: Can't teach an old dog new tricks. Oh, I don't know - I went to Uni at age 37 Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker Back to top Bryan Crotaz Guest Posted: Fri May 13, 2005 12:47 pm    Post subject: Re: Design Questions First Steps Quote: Can't teach an old dog new tricks. Oh, I don't know - I went to Uni at age 37 Joanna So that makes you an old dog... Hmmm self esteem problems, J? ;-) Bryan Back to top Jim Cooper Guest Posted: Fri May 13, 2005 1:27 pm    Post subject: Re: Design Questions First Steps Quote: So that makes you an old dog... Bitch, actually <vbg> Oh bugger, I just remembered she knows where I live. Damn!! Cheers, Jim Cooper __________________________________________ Jim Cooper [email]jcooper (AT) tabdee (DOT) ltd.uk[/email] Tabdee Ltd http://www.tabdee.ltd.uk TurboSync - Connecting Delphi to your Palm __________________________________________ Back to top krisztian pinter Guest Posted: Fri May 13, 2005 2:17 pm    Post subject: Re: Design Questions First Steps you are going to have a VB3 project Jim Cooper <jcooper (AT) tabdee (DOT) ltd.uk> wrote: Quote: Bitch, actually Oh bugger, I just remembered she knows where I live. Damn!! Back to top Joanna Carter (TeamB) Guest Posted: Fri May 13, 2005 2:25 pm    Post subject: Re: Design Questions First Steps "Bryan Crotaz" <bryan (AT) no (DOT) spam.for.me.please.inspirationmatters.com> a écrit dans le message de news: 4284a1ef$1 (AT) newsgroups (DOT) borland.com... Quote: So that makes you an old dog... Hmmm self esteem problems, J? That reminds me; wasn't I due to visit your kennel sometime this year ? ) Call me on my mobile. Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker Back to top Jim Cooper Guest Posted: Fri May 13, 2005 3:58 pm    Post subject: Re: Design Questions First Steps Quote: you are going to have a VB3 project I know, I've been bad :-) Cheers, Jim Cooper __________________________________________ Jim Cooper [email]jcooper (AT) tabdee (DOT) ltd.uk[/email] Tabdee Ltd http://www.tabdee.ltd.uk TurboSync - Connecting Delphi to your Palm __________________________________________ Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> Delphi OO design All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.