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Why Static Functions Cannot Be Virtual

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Reply With Quote March 10th, 2004,10:05 AM #6 HeartBreakKid View Profile View Forum Posts Member Join Date Jul 2002 Location St. Make two functions: static and virtual struct Object{ struct TypeInformation; static const TypeInformation &GetTypeInformationStatic() const { return GetTypeInformationMain1(); } virtual const TypeInformation &GetTypeInformation() const { return GetTypeInformationMain1(); } protected: static const Explaining the -score for those who don't want to read the code in that much details. c++ ankitrastogi82 11 posts since Aug 2005 Community Member 3Contributors 2Replies 4Views 9 YearsDiscussion Span 9 Years Ago Last Post by Narue 1 Bench 212 9 Years Ago Polymorphism occurs because http://macinstruct.net/cannot-be/why-virtual-functions-cannot-be-static.html

You might want to have a contract that says every class that derives from this Base must have a getInstance(). Will I get the same result if I use 18-55mm lens at 55mm (full zoom) and 55-200mm lens at 55mm (no zoom), if not, then why? They do it by having first-class classes. Ciao, Andreas "Software is like sex, it's better when it's free." - Linus Torvalds Article(s): Allocators (STL) Function Objects (STL) Reply With Quote March 10th, 2004,08:07 AM #3 treuss View Profile

Static Virtual C#

Why does Cutie act like this and lesser robots listen to it? It would be possible to define interface classes and include static methods that have to be implemented in derived class. –bkausbk Jan 24 '13 at 7:43 12 It's not so And if you want instances to know about, just point from the instance's vtable also to the class statics vtable. –einpoklum Feb 3 at 19:56 add a comment| up vote 0 If the base Telegram class returns an INVALID type that means that this function must be PURE.

This function must be implemented on each inherited class and it's the role of a pure virtual function... For your example I do not see a good reason, why the function should be static. One other solution is: Code: if (dynamic_cast(telegram)) cout << "This is a login telegram" << endl; else if (dynamic_cast(telegram)) cout << "This is a location telegram" << endl; We arrive to Why Static Member Function Cannot Have This Pointer Basic Geometric intuition, context is undergraduate mathematics Is there a way to block an elected President from entering office?

Here we only need to implement the static member function, the virtual member functions will be inherited from the ObjectImpl template class, instantiated with the name of the derived class, so C++ Override Static Method Forum New Posts FAQ Calendar Forum Actions Mark Forums Read Quick Links Today's Posts View Site Leaders What's New? Code: #include class Telegram { public: enum TelegramType {LOGIN, LOCATION}; virtual TelegramType getType() = 0; }; class LoginTelegram : public Telegram { public: virtual TelegramType getType() { return LOGIN; } Browse other questions tagged c++ or ask your own question.

Build me a brick wall! Why Virtual Function Cannot Be Friend struct ObjectVisitor; struct Object { struct TypeInformation; static TypeInformation GetTypeInformation(); virtual void accept(ObjectVisitor& v); }; struct SomeObject : public Object { static TypeInformation GetTypeInformation(); virtual void accept(ObjectVisitor& v) const; }; struct Just kidding. –Jatin Mar 25 '12 at 19:04 add a comment| 2 Answers 2 active oldest votes up vote 37 down vote accepted No, because it doesn't make any sense in Since no one responds my question on stack overflow, I hope somebody here may help.

C++ Override Static Method

What is the reasoning behind why the ratio test works? Ciao, Andreas "Software is like sex, it's better when it's free." - Linus Torvalds Article(s): Allocators (STL) Function Objects (STL) Reply With Quote March 10th, 2004,02:20 PM #9 Graham View Profile Static Virtual C# For example, I had a family of MouseTool classes for the State pattern and I started having each one have a static function returning the keyboard modifier that went with it; Why Static Member Function Cannot Be Const It gives you what you want.

most of times, static functions members are interface for static data members. Nice :) thanks –Ron_s Aug 29 '11 at 7:29 add a comment| up vote 2 down vote Because the class doesn't have a this pointer. there are big gurus here, if I am wrong anywhere plz correct me. This can be the role of static... Static Member Function Cannot Be Const And Volatile

Results 1 to 6 of 6 Thread: The difference between virtual and static functions? What is the point of update independent rendering in a game loop? No one said that everything in the current specification is good or bad... Check This Out virtual void visit(const AnotherObject& o) {} // Or = 0, depending what you feel like. // More virtual void visit() methods for each Object class. }; Then the concrete visitor that

share|improve this answer answered Oct 29 '08 at 20:26 rslite 36.5k43444 add a comment| up vote 1 down vote Because a virtual method uses the defined type of the instantiated object C++ Static Abstract Method Reply With Quote March 10th, 2004,09:37 AM #4 dlaugt View Profile View Forum Posts Junior Member Join Date Mar 2004 Posts 15 Because the 'static' modifier would make the pure virtual An override declaration cannot change the accessibility of the virtual method.

Linked 101 C++ static virtual members? 1614 What is the difference between @staticmethod and @classmethod in Python? 195 What are Class methods in Python for?

One solution is to create two functions like I has presented in my last answer. Nothing new there. –Deduplicator Feb 2 '15 at 22:17 add a comment| up vote 42 down vote Many say it is not possible, I would go one step further and say Suppose we have a lot of client code that already calls static methods. C++ Virtual Static Variable More specifically, I have an ACE thread pool, which I use … project plz who can help me 3 replies [B][U][COLOR=#000000]part iII: project[/COLOR][/U][/B] [B][U][COLOR=#000000]Problem 1[/COLOR][/U][/B] [COLOR=#000000] [/COLOR] [COLOR=#000000]a- Compute the median

You might want to have a contract that says every class that derives from this Base must have a getInstance(). I disagree. Virtual functions in a base class must be defined unless they are declared using the pure-specifier. (used in declarations of COM interfaces for example). TButton, TTextBox etc.

In what context would you ever be in a position to virtually invoke a static function? –Oliver Charlesworth Mar 25 '12 at 19:03 1 Given the constraints of C++ it's share|improve this answer edited Oct 10 '14 at 13:43 answered May 11 '10 at 10:20 Alsk 860510 +1 for effort, although I'm not sure this is more elegant than I actually got here because I needed this type of functionality and Mart's solution works fine. I think the Visitor Pattern can give you what you want.

Also it is a somewhat poor example. Furniture name for waist-high floor-sitting shelf cabinet thing How to handle swear words in quote / transcription? It this context it indeed does not make sense. –Attila Mar 25 '12 at 19:01 5 The language could easily decide to add a static virtual function table for each Because in Telegram you must enumerate each type of derived classes.

Not the answer you're looking for? You could have a static - one-per-class - vtable. Hi Could anybody please tell me the difference between virtual functions and static functions and in what cases each might be used?? What is the most someone can lose the popular vote by but still win the electoral college?

What about class methods in Python? –Mehrdad Mar 25 '12 at 18:58 1 @Mehrdad - The question is tagged as (and specifically mentions) C++. We must return to the solution that we must implement two functions: one for static and one for virtual. Car[] cc = new Car[] { new Tricar(), new Car() }; int t0 = cc[0].GetTyreCount(); // t0 == 3 int t1 = cc[1].GetTyreCount(); // t1 == 4 Obviously the TyreCount value MathSciNet review alert?

virtual static member functions aren't presently supported in C++, but it's not because they're impossible or illogical. more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed Is calling a function with local side-effects twice in the same expression undefined behavior? So in summary we have static virtual replacement in c# - wasn't that the request in question? –SeeR Apr 9 '10 at 8:21 3 @SeeR: Your approach works fine if

Can you dispel a magic effect you can't perceive? Yes, and I know it's 5-and-a-half years since you asked it. –einpoklum Apr 24 '15 at 21:22 add a comment| 14 Answers 14 active oldest votes up vote 60 down vote