Home > Cannot Be > Why Virtual Functions Cannot Be Static

Why Virtual Functions Cannot Be Static

Contents

I need to pass a non-static data member in one class (class Disks, data member disks) to another class (ToH) to … Templates vs Inheritence? 2 replies I hear this argument So, if you find yourself wanting this, you may want to rething your solution. They do it by having first-class classes. In particular allowing run time determination of meta data. have a peek here

The only reason that I don't want it to be freestanding is that the only place I'm using it is in this class, and I want to make that connection clear This is good if all thatis varying is the approval behavior, not the document behavior. foo::bar(); instead of Foo::bar();). You know that for every one of your Derived classes, the method never uses or alters member data.

Static Virtual C#

In fact I took it one better and made my base class method abstract to force the programmer to supply this field. It cannot use any non-static data. No, actually your reasoning is precisely what I would use to describe the restriction. Thanks again, cpp Jul 22 '05 #11 P: n/a Andy Venikov > Andy, take a look at the recent thread in comp.std.c++ about static virtual functions (titled "static member functions and

The reason for this topic is because … Please help with Pointers, Classes, Virtual Functions, and Abstract Classes 2 replies i have to make the C++ program that will have the Copyright Quinstreet Inc. 2002-2016 418,797 Members | 1,153 Online Join Now login Ask Question Home Questions Articles Browse Topics Latest Top Members FAQ home > topics > c / Step by Step Guide for Placement Preparation Reflection in Java Memory Layout of C Programs Heavy Light Decomposition Sorted Linked List to Balanced BST Generics in Java Aho-Corasick Algorithm for Pattern Why Static Member Function Cannot Have This Pointer If what you want is for for each class to have it's own implementation of isApproved, but be called not through the object invocation, but through a class invocation, then you

share|improve this answer answered Nov 30 '09 at 15:35 PaulJWilliams 14.4k13967 add a comment| up vote -1 down vote Like other's have said, there are 2 important pieces of information. 1) C# TBB updating metadata value Mimsy were the Borogoves - why is "mimsy" an adjective? If it's static, it can't be virtual. Reply With Quote March 10th, 2004,10:09 AM #7 Guysl View Profile View Forum Posts Member + Join Date Mar 2004 Location Israel Posts 638 The "problems" you've pointed at is with

Someone pointed how 'static virtual' and 'virtual' are conceptually at odds with one another. Why Virtual Function Cannot Be Friend divinity02 6 217 posts since Oct 2014 Community Member Fill dataset contents into respective text boxes? You have two functions which make same things... Then the compiler would errors if you don't overload it in your derived class.

C++ Override Static Method

Possible repercussions from assault between coworkers outside the office Is calling a function with local side-effects twice in the same expression undefined behavior? You cannot deference a null pointer for any reason. Static Virtual C# AFAIK, static functions are generally used to count the number of objects. Why Static Member Function Cannot Be Const Well...

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 You could implement the function in a what that the base Telegram class returns an INVALID type... Static functions mean "You can call this function without an object". How does Gandalf end up on the roof of Isengard? Static Member Function Cannot Be Const And Volatile

private: template void doVisit(const T& o) { result = T::GetTypeInformation(); } }; share|improve this answer edited Aug 21 '13 at 11:55 answered Aug 20 '13 at 14:39 Ben 2,2811419 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 It won't work if we need to call non-public functions though. Check This Out So pure virtual static functions are indeed in contradiction with themselves.

We found good solutions... C++ Static Abstract Method For some other derived class the rule would be different, but always a function of the author's name itself. plus - and this is important - the type of Document which should check the name.

Hi, I know that it is illegal in C++ to have a static pure virtual method, but it seems something like this would be useful when the following 2 conditions hold:

What you are referring to is called Late Static Binding; it's been recently added to PHP. You know that every one of your Derived classes will need to implement some method, but implement it differently, and that the base class cannot implement it. Solving a discrete equation How to prove that authentication system works, and that the customer is using the wrong password? C++ Virtual Static Variable What is the right design for a situation like this?

Not the answer you're looking for? Previous examples of large scale protests after Presidential elections in US? asked 8 years ago viewed 30687 times active 13 days ago Upcoming Events 2016 Community Moderator Election ends Nov 22 Linked 1 Redefine static fields in derived / nested classes in was a parameter, and I could call the appropriate constructor using the actual metaclass argument.

We have more line codes. So a static virtual member would be something that does not relate to any instance or any class. m_price is an implementation detail and adds nothing by being part of HouseDeed. I disagree.

share|improve this answer answered Nov 30 '09 at 15:33 Mads Elvheim Only non-static functions need a this pointer. Thank you. dotnetfiddle.net/scRWKD –user420667 Nov 7 '14 at 21:16 add a comment| up vote 6 down vote a static method exists outside of an instance of a class. People often want some kind of "static virtual function" because of duplication of code needed for being able to call the same function through static call "SomeDerivedClass::myfunction()" and polymorphic call "base_class_pointer->myfunction()".

Reply With Quote March 10th, 2004,05:12 PM #11 Assmaster View Profile View Forum Posts Member Join Date Jun 2003 Location Gjøvik, Norway Posts 204 Why can't you do this? How do you enchant items with Lapis Lazuli? Now he will only have only one instance of his class for the whole application. template< typename T > struct Check_constraints { static void check_for_default_constructor ( ) { T t = T( ); } static void check_for_static_method_foo( ) { T::foo( ); } }; }; struct B:

If not, then WHY? [duplicate] up vote 29 down vote favorite 6 Possible Duplicate: C++ static virtual members? To give a concrete example. You still need an object to call the method to identify the context in which the call should be made. Not the answer you're looking for?

You can check it your class has at least one virtual function then class size will increase by 4 (size of pointer) OM Perfect Answer thanks Durga " static function doesn't Hi, I know that it is illegal in C++ to have a static pure virtual method, but it seems something like this would be useful when the following 2 conditions hold: isApproved() must be implemented in any derived concrete class. 3. I've tried to compile the following code : #include using namespace std; class A { public: virtual static void f() {cout << "A's static method" << endl;} }; class B

For static there is no calling object, so it doesn't make sense to have both static and virtual on the same function .