BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Re: New Language Feature Goto page 1, 2, 3, 4  Next          BorlandTalk.com Forum Index -> Delphi Non-Technical View previous topic :: View next topic   Author Message Serge Dosyukov Guest Posted: Fri Aug 29, 2003 12:16 am    Post subject: Re: New Language Feature You can get this with interfaces implemented by objects -- Serge Dosyukov Borland Delphi 6 product certified MCP "Programming is not a job; it is a style of life." Back to top Erwien Saputra Guest Posted: Fri Aug 29, 2003 12:16 am    Post subject: Re: New Language Feature Max wrote: Quote: Delphi should support a garbage collection. Something like: I already has something like that using Interface, and D.Net will have it. Quote: {$GARBAGE ON} I think it should be all or nothing. Otherwise in some parts it might have garbage on, while on other parts have garbage off. Debugging can be challenging. Wien. Back to top David Clegg Guest Posted: Fri Aug 29, 2003 12:37 am    Post subject: Re: New Language Feature Erwien Saputra <erwien (AT) nospam (DOT) codeline.dot.net> wrote in news:3f4e9b5d$1 (AT) newsgroups (DOT) borland.com: Quote: I think it should be all or nothing. Otherwise in some parts it might have garbage on, while on other parts have garbage off. Debugging can be challenging. <ToungeFirmlyPlantedInCheek> Nah, bring it on! With the modern IDEs we have, this programming lark is getting too easy anyway. </ToungeFirmlyPlantedInCheek> -- Cheers, David Clegg dclegg_at_ebetonline_dot_com {$IFDEF Alessandro}Italian{$ELSE}French{$ENDIF} is the language of love. For everything else there's Delphi^h^h^h^h^h^h C#. Back to top Dave Nottage (TeamB) Guest Posted: Fri Aug 29, 2003 12:38 am    Post subject: Re: New Language Feature Alessandro Federici wrote: Quote: If you are willing to deal with recirsive references, temp-variables that the compilers plugs in your code (and which really mess things up sometimes) and also remember to use weak references <G> It's slightly more complicated with ref counting and sort of slower. Can you give some examples? I guess I haven't had the kind of troubles you've had. -- Dave Nottage (TeamB) Back to top Alessandro Federici Guest Posted: Fri Aug 29, 2003 12:41 am    Post subject: Re: New Language Feature "Serge Dosyukov" <serge@argosoftware[DOT]com> wrote Quote: Apparently I'm oppose to garbage collector at this moment because it making a language less structural (I hope it is a correct word) People will forgot to free objects or will expect what object isn't free yet... I was not too pro-GC either but I changed my pov on the matter. Point is that even with interfaces it's not always true it happens when you believe it should... It really bit me and Marc in the but many times. Quote: This is good for .Net, because it is paradigm of .net, it might be a good idea for today's mind. And I agree with Erwien, it is all or nothing Ditto. I have to admit it's something that should have always been there... Back to top Alessandro Federici Guest Posted: Fri Aug 29, 2003 12:48 am    Post subject: Re: New Language Feature "Dave Nottage (TeamB)" <davidn (AT) nospamola (DOT) smartchat.net.au> wrote Quote: If you are willing to deal with recirsive references, temp-variables that the compilers plugs in your code (and which really mess things up sometimes) and also remember to use weak references <G> It's slightly more complicated with ref counting and sort of slower. Can you give some examples? I guess I haven't had the kind of troubles you've had. Yes but I will be quick (I promise I can answer more precisely if you need me to <G>). The temp variable thing is complex and I cleaned up all my code not to get into those situations anymore so I don't have a real example (anymore). Basically happens when you use "as" and in a set of other situations such as results of methods. Actually I have one (sort of new. I hit it yesterday). begin pkg := LoadPackage(whatever); GetprocAddress(bla blah) myintf := PackageFunction ThatReturnsOneIntd; UnloadPackage; <BAM> end; Basically you need to NIL myintf begore unloading the package. This is a silly example, but it is just to say it's not as simple as with GC... The "as" issue is nastier instead but again, I 've no handy sample (anymore). The recursive refernce thing instead is simple to get into: Master has a refernce to child and child has one to master. When you have a situation like this, you have to use a weak pointer in either one, otherwise objects won't get freed. The speed thing was demonstrated by MS at a ceonference here in Chicago. The AddRef/Release overhead was seriously big. Back to top Alessandro Federici Guest Posted: Fri Aug 29, 2003 12:50 am    Post subject: Re: New Language Feature "Alessandro Federici" <nomore (AT) spam (DOT) forme> wrote FTR, this stuff is not really Delphi specific, don't get me wrong Happens with VC++ and COM in general as well. It's pattern related. I like refcounting don't get me wrong. It's just that is not *that simple* all the times ) Back to top Dave Nottage (TeamB) Guest Posted: Fri Aug 29, 2003 12:54 am    Post subject: Re: New Language Feature Alessandro Federici wrote: Quote: begin pkg := LoadPackage(whatever); GetprocAddress(bla blah) myintf := PackageFunction ThatReturnsOneIntd; UnloadPackage; BAM end; Interesting. If I have time, I'll have a play with this one. Quote: The recursive refernce thing instead is simple to get into: Master has a refernce to child and child has one to master. When you have a situation like this, you have to use a weak pointer in either one, otherwise objects won't get freed. OK.. I was aware of that one, but thanks <g> Quote: The speed thing was demonstrated by MS at a ceonference here in Chicago. The AddRef/Release overhead was seriously big. OK.. I'll have a look and/or play with this one when I have time. -- Dave Nottage (TeamB) Back to top Ingvar Nilsen Guest Posted: Fri Aug 29, 2003 1:18 am    Post subject: Re: New Language Feature Alessandro Federici wrote: Quote: You can get this with interfaces implemented by objects If you are willing to deal with recirsive references, temp-variables that the compilers plugs in your code (and which really mess things up sometimes) and also remember to use weak references <G> It's slightly more complicated with ref counting and sort of slower. You're exaggerating. I understand it can be complicated under certain circumstances, but talking for myself, I use interfaces all the time, love interfaces, cannot program without them. I always add debug code to test whether they are freed. They are. All is fine <g> When you start using UML in Delphi, you will really understand how to appreciate interfaces, UML and interfaces seem to be made for each others :) -- Ingvar Nilsen Back to top Alessandro Federici Guest Posted: Fri Aug 29, 2003 2:54 am    Post subject: Re: New Language Feature "Ingvar Nilsen" <telcontr@[Remove-This-Part]online.no> wrote Quote: You're exaggerating. I understand it can be complicated under certain circumstances, but talking for myself, I use interfaces all the time, love interfaces, cannot program without them. I love interfaces too You should know me <G> Anyhow, I made some concrete examples. Quote: I always add debug code to test whether they are freed. They are. All is fine <g Actually that depends what you're doing. That is all I am saying (and backing up with examples). Intfs are *great*. No questions. Just not always that simple. GC is simpler (probabily). Quote: When you start using UML in Delphi, you will really understand how to appreciate interfaces, UML and interfaces seem to be made for each others I never needed UML to love interfaces and our products are *heavily* based on those and on tricks about them not everybody knows <G> Back to top Alessandro Federici Guest Posted: Fri Aug 29, 2003 3:09 am    Post subject: Re: New Language Feature "Alessandro Federici" <nomore (AT) spam (DOT) forme> wrote Quote: When you start using UML in Delphi To enforce my message: OO without interfaces is worth (almost) squat. It's a whole different world once you start using them What started me on interfaces is COM. That's another reason for which I consider it something every Delphi developer should know well. But that's me ;-) Back to top Alessandro Federici Guest Posted: Fri Aug 29, 2003 3:23 am    Post subject: Re: New Language Feature "Ingvar Nilsen" <telcontr@[Remove-This-Part]online.no> wrote Quote: When you start using UML in Delphi, you will really understand how to appreciate interfaces, UML and interfaces seem to be made for each others BTW keep in mind that reference counting for interfaces is a COMism/Delphism. Interfaces have a lot of sense and exist without ref counting in other languages. IMHO refcounting is of very little weight compared to the other benefits of interfaces (i.e. breaking vertical dependencies on parent classes). Back to top Erwien Saputra Guest Posted: Fri Aug 29, 2003 4:03 am    Post subject: Re: New Language Feature Alessandro Federici wrote: Quote: I never needed UML to love interfaces and our products are *heavily* based on those and on tricks about them not everybody knows Hei, you are not allowed to make people curious to buy your product and to find the trick in this NG, you know... :) That kind of post should be in 3rd party NG. ^_^ Wien. Back to top Karl Waclawek Guest Posted: Fri Aug 29, 2003 4:36 am    Post subject: Re: New Language Feature "Vincent Parrett (Atozed Software)" <vincent@.nospam.atozedsoftware.com> wrote in message news:3f4ed139 (AT) newsgroups (DOT) borland.com... Quote: I can think of one simple case that can be a real gotcha when using interfaces. See the example unit code below.. call NewITest to create an ITest object, and then call the DoSomething Method. You would expect the reference count to be 1, but in fact it's 2. In this simple example this is no big deal as somehow the object still gets released.. however if something else increments the reference count (ie something internal to the code) then that's when the real problems start happening.... if I have code like this : var myTest : ITest; begin myTest := NewITest; mTest.DoSomething; end; It is quite likely that myTest and the Result variable in NewITest both contribute to the reference count separately, as the Result variable must exist independently. This is because the compiler must be prepared to handle the case where NewITest is called without assigning the result to a variable. I assume (without testing it) that even if you set myTest := nil you still have a reference count of 1, and it only goes to zero when the (hidden) Result variable goes out of scope. The same issues arise with the "as" operator and the use of "with". Check out QC # 2437. Quote: This would be fine, however if something internal to the DoSomething method caused an addref then you could end up with an orphaned object without realising it. Replacing myTest := NewITest with this myTest := TTest.Create; results in a ref count of 1 and it's less likely that you will end up with an orphaned object. Actually, the above is fairly safe, except for border cases like in QC # 2437. But orphaned objects won't happen this way. Karl Back to top Alessandro Federici Guest Posted: Fri Aug 29, 2003 4:59 am    Post subject: Re: New Language Feature "Erwien Saputra" <erwien (AT) nospam (DOT) codeline.dot.net> wrote Quote: Hei, you are not allowed to make people curious to buy your product and to find the trick in this NG, you know... That kind of post should be in 3rd party NG. ^_^ Actually I am thinking of a BDN article ;-) Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> Delphi Non-Technical All times are GMT Goto page 1, 2, 3, 4  Next Page 1 of 4   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.