BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Iterator vs For loop          BorlandTalk.com Forum Index -> Delphi OO design View previous topic :: View next topic   Author Message Peter Morris [Droopy Eyes Guest Posted: Mon Jan 05, 2004 9:25 pm    Post subject: Iterator vs For loop Hi all Is there any advantage to an iterator over a for loop where a) The list is already exposed by its owner b) The list is not a composite list Pete Back to top Joanna Carter (TeamB) Guest Posted: Mon Jan 05, 2004 10:00 pm    Post subject: Re: Iterator vs For loop Peter Morris [Droopy Eyes Software] wrote: Quote: Is there any advantage to an iterator over a for loop where a) The list is already exposed by its owner b) The list is not a composite list If the list already has an indexed Item[] property then an Iterator could be seen as superfluous. However, Iterators have their benefits in constructing tools like skip iterators that filter a list, or tree iterators where the Tree has no concept of indexing. Iterators are best obtained from the list that they will iterate i.e. the list should have a GetIterator method. Could you explain a & b, they do not mean much to me at the moment? Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker Back to top Marc Rohloff Guest Posted: Mon Jan 05, 2004 10:02 pm    Post subject: Re: Iterator vs For loop Peter Morris [Droopy Eyes Software] wrote on Mon, 5 Jan 2004 21:25:57 - 0000 ... Quote: Is there any advantage to an iterator over a for loop where a) The list is already exposed by its owner b) The list is not a composite list For loops are generally considerably faster than for loops, however an iterator can offer a good level of abstraction even in a simple case like this. For example you may later want to make your list a composite. Well designed iterators can also insulate your code from the impact of changes (additions and deletions) to the list while you are busy iterating over it. Marc Rohloff marc rohloff at bigfoot dot com Back to top Joanna Carter (TeamB) Guest Posted: Mon Jan 05, 2004 10:03 pm    Post subject: Re: Iterator vs For loop Marc Rohloff wrote: Quote: For loops are generally considerably faster than for loops But which for loop is faster? :-) Quote: Well designed iterators can also insulate your code from the impact of changes (additions and deletions) to the list while you are busy iterating over it. Good point, I have the Iterator observe the list and when a deletion occurs, I can shortcut terminate the Iterator. Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker Back to top Carl Caulkett Guest Posted: Mon Jan 05, 2004 10:40 pm    Post subject: Re: Iterator vs For loop Joanna Carter (TeamB) wrote: Quote: Marc Rohloff wrote: For loops are generally considerably faster than for loops But which for loop is faster? The first one obviously. Like, duh! <g> -- Carl Back to top Ritchie Guest Posted: Mon Jan 05, 2004 11:47 pm    Post subject: Re: Iterator vs For loop In article <3ff9e026$1 (AT) newsgroups (DOT) borland.com>, [email]joannac (AT) btinternetXX (DOT) com[/email] says... Quote: Marc Rohloff wrote: | For loops are generally considerably faster than for loops But which for loop is faster? LOL - voops :) Quote: Good point, I have the Iterator observe the list and when a deletion occurs, I can shortcut terminate the Iterator. My own variant does a nil-and-pack type of operation where deleted items are nil-ed (and packed when all iterators go away), and every created iterator gets the Count of the list when it's created, so it never goes past it even if items are added later. Simplistic way to keep a relatively consistent view of the list, but it works well :) Quote: Joanna Happy New Year, Joanna :) -- Ritchie Annand Senior Software Architect http://www.malibugroup.com http://nimble.nimblebrain.net http://wiki.nimblebrain.net Back to top Joanna Carter (TeamB) Guest Posted: Mon Jan 05, 2004 11:50 pm    Post subject: Re: Iterator vs For loop Ritchie wrote: Quote: Happy New Year, Joanna Ta muchly and ditto to you :-) Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker Back to top Bryan Crotaz Guest Posted: Tue Jan 06, 2004 3:37 am    Post subject: Re: Iterator vs For loop Quote: For loops are generally considerably faster than for loops, however an iterator can offer a good level of abstraction even in a simple case like this. For example you may later want to make your list a composite. Well designed iterators can also insulate your code from the impact of changes (additions and deletions) to the list while you are busy iterating over it. ESPECIALLY when multithreading! Don't always want to lock the list to iterate it! Bryan Back to top Marc Rohloff Guest Posted: Tue Jan 06, 2004 1:34 pm    Post subject: Re: Iterator vs For loop Joanna Carter (TeamB) wrote on Mon, 5 Jan 2004 22:03:30 -0000 ... Quote: Marc Rohloff wrote: | For loops are generally considerably faster than for loops But which for loop is faster? You guys are a tough audience! But you all understood that what I meant to say was: For loops are generally considerably faster than iterators. Right? Marc Rohloff marc rohloff at bigfoot dot com Back to top Peter Morris [Droopy Eyes Guest Posted: Tue Jan 06, 2004 1:45 pm    Post subject: Re: Iterator vs For loop Don't worry Rold, I understood ;-) Quote: You guys are a tough audience! But you all understood that what I meant to say was: For loops are generally considerably faster than iterators. Right? Back to top Rudy Velthuis (TeamB) Guest Posted: Sun Jan 11, 2004 11:05 am    Post subject: Re: Iterator vs For loop Marc Rohloff wrote: Quote: For loops are generally considerably faster than for loops Er... -- Rudy Velthuis (TeamB) "Hemingway was a jerk." - Harold Robbins 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.