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Why Virtual Functions Cannot Be Static


I still don't understand this. … What's the use of namespaces? 5 replies Well to start let me say that I'm only a newbie, as my status says, but after a m_price is an implementation detail and adds nothing by being part of HouseDeed. Indeed, to give it context, I could have it operate on _documentAuthor directly instead of passing that in as an argument. Can we have a static virtual functions? useful reference

GO OUT AND VOTE Why is looping over find's output bad practice? Victor Jul 22 '05 #7 P: n/a cppaddict Karl, Thanks for your reply. share|improve this answer edited Aug 22 '12 at 16:44 answered Nov 30 '09 at 15:39 Nate C-K 4,37311531 That's going to cost me performance - unless the compiler can But what exactly is possible, let's narrow down.

Static Virtual C#

Well...there is no problem at the end. I've got a couple more questions though... static function members don't need an object to be called, therefore dynamic link of virtual function cannot be accomplished.

Limit computation technology in a futuristic society Why were pre-election polls and forecast models so wrong about Donald Trump? Making it virtual and static would mean a contradiction. You use them when you want to execute something class-specific without any context, meaning without an object of that class. Why Static Member Function Cannot Have This Pointer So we have the following: 1.

What is the point of update independent rendering in a game loop? C++ Override Static Method My cat sat on my laptop, now the right side of my keyboard types the wrong characters Why do some banks have more than one routing number in the US? One point, the introduction of the strategy pattern doesn't necessarily mean the elimination of the virtual function in the document class : virtual bool isApproved( ){ return _approver->isApproved( authorName) ;}; Here Kind of the poor man's factory pattern :) share|improve this answer answered Oct 29 '08 at 20:46 Alan 4,5261722 1 The fact that c# does not support static virtual methods

was a parameter, and I could call the appropriate constructor using the actual metaclass argument. Why Virtual Function Cannot Be Friend Possible repercussions from assault between coworkers outside the office Is calling a function with local side-effects twice in the same expression undefined behavior? The request cannot be fulfilled by the server current community chat Stack Overflow Meta Stack Overflow your communities Sign up or log in to customize your list. Start a coup online without the government intervening Why do some banks have more than one routing number in the US?

C++ Override Static Method

Hope that helps! Bottom line, is if you want to change behavior based on which subclass an instance is, then the methods should have been virtual methods on the base class, not static methods. Static Virtual C# 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 Be Const How does Gandalf end up on the roof of Isengard?

Pointers to class members are special in semantics and syntax. http://bovbjerg.net/cannot-be/virtual-path-cannot-be-null.php In other words, to call a virtual function, you need an object. isApproved() must be a simple function of a string. isApproved() must be implemented in any derived concrete class. 3. Static Member Function Cannot Be Const And Volatile

So there is a wide gap between the two concepts hence it is not possible" I know the reasoning above looks stupid but can you provide some solid grounds to it The time now is 12:20 AM. Then I would no longer feel that it "should" be static. http://bovbjerg.net/cannot-be/variable-cannot-be-referenced-from-a-static-context.php That's not unlike decltype(foo)::bar(); but that again would be statically bound.

This can be the role of static... C++ Static Abstract Method dave "cppaddict" wrote in message news:eo********************************@4ax.com...In the strategy pattern approach, you will have a data member whichprovides the IsApproved() method. Without a "live" object, you have no way to access any virtual function.

This would be too awkward if you have to declare/define classes for every variation.

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 If you make isApproved a public function, then you can usea template function like this: template void processDocument(documnetAuthor){ if (T::isApproved(documentAuthor)) T::SomeNonVirtualF; else T::SomeOtherNonVirtualF;} and call it like this processDocument(documentAuthor); We start with an abstract base class, that provides the interface for all the object types: class Object { public: virtual char* GetClassName() = 0; }; Now we need an actual C++ Virtual Static Variable For some other derived class the rule would be different, but always a function of the author's name itself.

A quick google can tell you more about the virtual function lookup table. static on a function in a class means that the function doesn't need an object to operate on. Suppose we have a lot of client code that already calls static methods. Get More Info Maybe for a derived KinkosDocument, isApproved() returns true if the author's name begins with "A", and is otherwise false.

Maybe for a derived KinkosDocument, isApproved() returns true if the author's name begins with "A", and is otherwise false. Thus it should be static. No. >I know the reasoning above looks stupid but can you provide some solid grounds to it ? virtual functions in a class needs the this pointer, and is very coupled to the class, hence they can't be static.