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Polymorphic Queue 15 Years Ago by metdos Hello Everyone, I'm trying to implement a Polymorphic Queue. Here is my trial: [CODE]QQueue <Request *>…decodeFromTcpMessage(); } }[/CODE] Unfortunately, I could not manage to make work Polymorphic Queue with this code because of the reason I mentioned… improvement of my code or a new implementation of polymorphic queue. Thanks. Polymorphic write-to-file with abstract inheritance problem (not as bad as it sounds) 14 Years Ago by lacoffo … Java and I'm having a little trouble on a polymorphic write-to-file function. Let me quickly explain my project… Main program I should be able to call this function polymorphic like array[index].WriteData(), and each Horse and Cow should… Polymorphic Virus 16 Years Ago by Seakros … that it might be a [COLOR="Green"]"polymorphic"[/COLOR] virus (which apparently changes itself everytime it is… Passing polymorphic pointer by reference to function 14 Years Ago by TheWolverine … I am struggling with how to working with a polymorphic pointer as a function input parameter, by reference. … protype for setParameterOfDerivedClass() I want to use a polymorphic pointer to be able to pass objects of DerivedClass… trying to avoid doing that by using the polymorphic pointer. Any feedback would be greatly appreciated. Thanks!… Policy vs polymorphic timing 13 Years Ago by daviddoria … tight loop is much faster than using a polymorphic function. However, I setup this demo and…The policy version takes between 2-3x longer than the polymorphic version. [code] #include <iostream> #… const float b) { return a + b; } }; // Polymorphic version class DoOperation { public: virtual float Run(const float a… Help(polymorphic variables in java) 17 Years Ago by java.cream Hi all, I need help in polymorphic variables concept ,Are there any polymorphic variables in the code belowand Explain why? thnks.. [CODE]class… Re: Passing polymorphic pointer by reference to function 14 Years Ago by TheWolverine … here. My question pertained particularly to the idea of passing polymorphic pointers to functions, and I've now figured out how… Re: Policy vs polymorphic timing 13 Years Ago by mike_2000_17 … is due to the side-effect of creating a dynamic polymorphic object, while the static case probably determines that the entire… Re: Policy vs polymorphic timing 13 Years Ago by m4ster_r0shi … OperationPolicyDiv { double Operation(double a, double b) { return a / b; } }; // polymorphic version struct DoOperation { virtual double Run(double a, double b… What is needed for a C++ member function of a class to behave polymorphic? 16 Years Ago by viki0077 What is needed for a C++ member function of a class to behave polymorphic? Please can anyone answer me to this, and if you can give me some example. Thanks. Re: What is needed for a C++ member function of a class to behave polymorphic? 16 Years Ago by Danny_501 Look at the C++ section of this link: [URL="http://en.wikipedia.org/wiki/Polymorphism_in_object-oriented_programming#C.2B.2B"]wiki: Polymorphism_in_object-oriented_programming[/URL] I guess the talk() function is behaving polymorphic, because its in each of the inherited classes. Re: What is needed for a C++ member function of a class to behave polymorphic? 16 Years Ago by NicAx64 …: Polymorphism_in_object-oriented_programming[/URL] I guess the talk() function is behaving polymorphic, because its in each of the inherited classes.[/QUOTE] No… Re: Polymorphic Queue 15 Years Ago by Banfa The problem is at line 12 loginRequest is created on the stack, that means that it is automatically has the lifetime of the code block it is in which is the if statement. You take pointers to it and put them on your queue but that doesn't change the fact that the original object is deleted when its lifetime expires. You need an object whos … Re: Polymorphic Queue 15 Years Ago by metdos Yes it is a QT class, I used it just for coherence. Re: Polymorphic Queue 15 Years Ago by metdos [QUOTE]Change how you use your queue so that the pointers it contains always point to objects allocated using new. When you remove items from the queue remember to delete them once you are finished with them. Possibly look into using std::auto_ptr or a smart pointer or handle class.[/QUOTE] Can you give an example? Re: Polymorphic Queue 15 Years Ago by thelamb You have already done it... Look at how you declare your 'request': [code]Request *request=new Request();[/code] So 'request' is now allocated on the heap.. means you are responsible for cleaning it up (delete request; somewhere in the code). Then, you say.. ok I want 'request' to point to a LoginRequest. [code]LoginRequest loginRequest;… Re: Polymorphic Queue 15 Years Ago by metdos [QUOTE]So I dont really understand why you do the first "new Request();".. doesnt this make more sense:[/QUOTE] Because at that level I don't know which subclass is it, and if statements will continue like this: [CODE]# if(request->requestType==REQUEST_LOGIN){ LoginRequest loginRequest; request=&loginRequest; requests.… Re: Polymorphic Queue 15 Years Ago by Banfa Actually this piece of code is not really interested in the sub-class at all. It just needs a Request* in order to queue the request. It looks like you could use a factory method. A factory method is often a static member of a base class that accepts data and uses the data to create a sub-class of that base but returns a base class pointer.… Re: Polymorphic Queue 15 Years Ago by metdos This version solved my problem. [CODE]QQueue <Request *> requests; while(...) { QString line = QString::fromUtf8(client->readLine()).trimmed(); if(...)){ Request *request=new Request(); request->tcpMessage=line.toUtf8(); request->decodeFromTcpMessage(); //this initialize variables in … Re: Polymorphic write-to-file with abstract inheritance problem (not as bad as it sounds) 14 Years Ago by JamesCherrill I would pass the PrintWriter as a parameter to all the WriteData methods. So it's created and closed in the same place as the loop (eg your Main program). Re: Polymorphic write-to-file with abstract inheritance problem (not as bad as it sounds) 14 Years Ago by lacoffo Worked like a charm :) Thanks a lot man:) Re: Polymorphic Virus 16 Years Ago by Seakros I forgot to add that I tried to install Vundofix but it is not installing for some reason. At the very end of the process it just stops, tells me there is an error and uninstall the components it installed. Re: Polymorphic Virus 16 Years Ago by smith_ use superantispyware may be it will help you fee download here >[url]http://www.superantispyware.com/[/url]. if you get still problem go SNIP Polymorphic Problem 15 Years Ago by BobTheLob Okay, so i've been trying to get this code to work for quite some time, and i'm about to go bonkers. Hopefully y'all can help me out with this problem because I need to hand this one in soon. My problem is I need to make an array of objects. Check. (Note that the classes i'm using extend a superclass, Ship). Now I need to set information into … Re: Polymorphic Problem 15 Years Ago by moutanna Hi Can you provide the code of the Ship class please? Re: Polymorphic Problem 15 Years Ago by BobTheLob [CODE]public class Ship { public String shipName; private String yearBuilt; public void setName (String n) { shipName = n; System.out.println("Inside the setName Super"); } public void setYear (String y) { yearBuilt = y; System.out.println("Inside the setYear Super"); } public String toString () { … Re: Polymorphic Problem 15 Years Ago by moutanna You have this declaration in the Boats calss Ship[] type = new Ship[2]; and the Ship class have no methode with the setMax; in facte this method is declard in the CruiseShip Class. So itis not permited to call it over the type[1] even if you do this instructio: type[1] = new CruiseShip(); To avoid this move the function setMax with it'… Re: Polymorphic Problem 15 Years Ago by moutanna Another alternative is to declare the Ship class as abstract with some setMax as abstract function. you need also to move the maxPass to the Ship class with the protected modifier. Re: Polymorphic Problem 15 Years Ago by moutanna the second proposition result in many changes Re: Polymorphic Problem 15 Years Ago by BobTheLob Excellent. However, in the project description, I need to have a CruiseShip class that extends the Ship class. And then I need to demonstrate the multiple classes I made in a program with a Ship array. And then assign various Ship, CruiseShip, and CargoShip objects to the array elements. So how would I go about doing this?