BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  DYNAMIC - overload?          BorlandTalk.com Forum Index -> C++ Builder (VCL Components Development) View previous topic :: View next topic   Author Message masi Guest Posted: Fri Mar 10, 2006 3:03 pm    Post subject: DYNAMIC - overload? 1) what does exactly mean the word DYNAMIC that i must type when for example i want to modify the standard handler of an event like MouseDown: DYNAMIC void __fastcall MouseDown(TMouseButton Button, TShiftState Shift, int X, int Y); //--------------------------------------------------------------------------- void __fastcall MyControl::MouseDown(TMouseButton Button, Classes::TShiftState Shift, int X, int Y) { // do something before TCustomControl::MouseDown(Button,Shift,X,Y); // perform standard handling, including calling handler // do something after } 2) what does exactly mean the keyword overload in the pascal declaration of a method? what is the correspondance in c++? thanks masi urbano Back to top masi Guest Posted: Fri Mar 10, 2006 11:03 pm    Post subject: Re: DYNAMIC - overload? What I'm trying to do is to modify the TVirtualStringTree class in order to implement a new event that behaves like TListView::OnSelectItem event. I'm working so: typedef void __fastcall (__closure *NodeChangeSelectEvent)(TObject *Sender, TVirtualNode *Node, bool Selected); class PACKAGE MyVirtualTree : public TVirtualStringTree { private: NodeChangeSelectEvent POnNodeChangeSelect; // event trigger void __fastcall NodeChangeSelect(TVirtualNode *Node, bool Selected); protected: void __fastcall AddToSelection(TVirtualNode *Node); void __fastcall RemoveFromSelection(TVirtualNode *Node); public: __fastcall MyVirtualTree(TComponent* Owner); __published: __property NodeChangeSelectEvent OnNodeChangeSelect = {read=POnNodeChangeSelect, write=POnNodeChangeSelect}; }; //--------------------------------------------------------------------------- __fastcall MyVirtualTree::MyVirtualTree(TComponent* Owner) : TVirtualStringTree(Owner) { /// } //--------------------------------------------------------------------------- void __fastcall MyVirtualTree::AddToSelection(TVirtualNode *Node) { TVirtualStringTree::AddToSelection(Node); // fire event NodeChangeSelect(Node,true); } //--------------------------------------------------------------------------- void __fastcall MyVirtualTree::RemoveFromSelection(TVirtualNode *Node) { TVirtualStringTree::RemoveFromSelection(Node); // fire event NodeChangeSelect(Node,false); } //--------------------------------------------------------------------------- void __fastcall MyVirtualTree::NodeChangeSelect(TVirtualNode *Node, bool Selected) // event trigger { if (!Enabled) return; if (POnNodeChangeSelect != NULL){ POnNodeChangeSelect(this,Node,Selected); } } //--------------------------------------------------------------------------- Then I would expect that when I select or deselect an item, MyVirtualTree::AddToSelection or MyVirtualTree::RemoveFromSelection would be called, but it doesn't happen at all! in VirtualTrees.hpp (machine generated header for VirtualTrees.pas) I found: protected: void __fastcall AddToSelection(PVirtualNode Node)/* overload */; where /* overload */ is just an auto-generated comment so, as far as I know, what I have to do is to declare in my class MyVirtualTree void __fastcall AddToSelection(PVirtualNode Node); I tried so and even void __fastcall AddToSelection(TVirtualNode *Node); which is the same, but none works. Any ideas? thanks masi urbano Back to top Remy Lebeau (TeamB) Guest Posted: Fri Mar 10, 2006 11:03 pm    Post subject: Re: DYNAMIC - overload? "masi" <masiurb (AT) tin (DOT) it> wrote in message news:44118344$1 (AT) newsgroups (DOT) borland.com... Quote: what does exactly mean the word DYNAMIC that i must type when for example i want to modify the standard handler of an event like MouseDown: DYNAMIC is a precompiler macro that expends to __declspec(dynamic). Any VCL method that is declared with the 'dynamic' keyword in Delphi has to be declared with __declspec(dynamic) in C++ in order to operate proprly. A dynamic method is essentially the same as a virtual method, but it has slightly different semantics internally, which you are read about in the documentation for __declspec(). Quote: what does exactly mean the keyword overload in the pascal declaration of a method? Exactly what its name suggests - it specifies that the method is overriding a virtual or dynamic method in a base class. In Delphi, the 'override' keyword is required in order to actually override the method. In C++, there is no such keyword. Overriding is always implicitally handled. Gambit Back to top Remy Lebeau (TeamB) Guest Posted: Sat Mar 11, 2006 1:03 am    Post subject: Re: DYNAMIC - overload? "masi" <masiurb (AT) tin (DOT) it> wrote in message news:4411f2fa (AT) newsgroups (DOT) borland.com... Quote: I would expect that when I select or deselect an item, MyVirtualTree::AddToSelection or MyVirtualTree::RemoveFromSelection would be called, but it doesn't happen at all! Those methods are not virtual or dynamic to begin with, so you cannot override them. You will have to either find another way to accomplish what you want, or else you will have to edit the original Delphi source code for TVirtualStringTree to make the methods virtual and then recompile that component. Quote: void __fastcall AddToSelection(PVirtualNode Node)/* overload */; where /* overload */ is just an auto-generated comment Sorry, I thought you said 'override' earlier. The 'overload' keyword is completely different and unrelated. It means exactly what its name suggests - the method is overloaded, which means the same thing in Delphi that it does in C++. A method is overloaded when there are more than 1 method of the same name in the same class, just with different parameter lists. Gambit Back to top Rudy Velthuis [TeamB] Guest Posted: Sun Mar 12, 2006 2:03 am    Post subject: Re: DYNAMIC - overload? At 14:46:26, 10.03.2006, masi wrote: Quote: 1) what does exactly mean the word DYNAMIC that i must type when for example i want to modify the standard handler of an event like MouseDown: Dynamic is a special kind of virtual, first defined for the Turbo Pascal compiler, when dat segments were limited, and virtual tables of, for instance, the Turbo Vision framework could easily gobble up all the 64k available. So Borland defined some kind of slower, but less memory consuming virtual method table, the dynamic method table. It does not contain a long list (indexed array) of ALL the function pointers, which can immediately be accessed by looking at a certain index, for each class. Instead, it contains only the methods the class overrides, and the associated index value (i.e. it is an associative array). Like for virtual methods, the function pointer is found at runtime, but of course, this takes longer, since it requires a search through all indices in the DMT (I guess they are sorted, so this could perhaps be done with a binary search) to see if the function is defined there. If it is not, the compiler will continue with the direct ancestor, and so on, until it is finally found. That is MUCH slower, of course. It is still in use for functions that are not so often overridden. A left over from the Delphi 1 and Turbo Pascal days. BCB has extensions that allow it to use such dynamic methods as well. -- Rudy Velthuis [TeamB] http://rvelthuis.de/ "I am ready to meet my Maker. Whether my Maker is prepared for the great ordeal of meeting me is another matter." -- Winston Churchill. Back to top masi Guest Posted: Mon Mar 13, 2006 1:03 pm    Post subject: Re: DYNAMIC - overload? Quote: Those methods are not virtual or dynamic to begin with, so you cannot override them. Ok, this is the correct explanation. thanks Quote: You will have to either find another way to accomplish what you want, My opinion is that may be impossible: the only virtual methods are those who are directly involved with existing events handling, like DoGetImageIndex, DoGetText, etc.. In effects, this seems a correct philosophy in general terms. Quote: or else you will have to edit the original Delphi source code for TVirtualStringTree to make the methods virtual and then recompile that component. yes, this may be the solution, although not much in the spirit of object oriented programming in my opinion thank you for your help masi urbano Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> C++ Builder (VCL Components Development) 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.