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  • How do I change the class of an object to a subclass of its current class in C++?

    - by Jared P
    I have an array of pointers to a base class, so that I can make those pointers point to (different) subclasses of the base class, but still interact with them. (really only a couple of methods which I made virtual and overloaded) I'm wondering if I can avoid using the pointers, and instead just make an array of the base class, but have some way to set the class to the subclass of my choosing. I know there must be something there specifying the class, as it needs to use that to look up the function pointer for virtual methods. By the way, the subclasses all have the same ivars and layout. Note: the design is actually based on using a template argument instead of a variable, due to performance increases, so really the abstract base class is just the interface for the subclasses, which are all the same except for their compiled code. Thanks

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  • Using classes for the first time,help in debugging

    - by kaushik
    here is post my code:this is no the entire code but enough to explain my doubt.please discard any code line which u find irrelavent enter code here saving_tree={} isLeaf=False class tree: global saving_tree rootNode=None lispTree=None def __init__(self,x): file=x string=file.readlines() #print string self.lispTree=S_expression(string) self.rootNode=BinaryDecisionNode(0,'Root',self.lispTree) class BinaryDecisionNode: global saving_tree def __init__(self,ind,name,lispTree,parent=None): self.parent=parent nodes=lispTree.getNodes(ind) print nodes self.isLeaf=(nodes[0]==1) nodes=nodes[1]#Nodes are stored self.name=name self.children=[] if self.isLeaf: #Leaf Node print nodes #Set the leaf data self.attribute=nodes print "LeafNode is ",nodes else: #Set the question self.attribute=lispTree.getString(nodes[0]) self.attribute=self.attribute.split() print "Question: ",self.attribute,self.name tree={} tree={str(self.name):self.attribute} saving_tree=tree #Add the children for i in range(1,len(nodes)):#Since node 0 is a question # print "Adding child ",nodes[i]," who has ",len(nodes)-1," siblings" self.children.append(BinaryDecisionNode(nodes[i],self.name+str(i),lispTree,self)) print saving_tree i wanted to save some data in saving_tree{},which i have declared previously and want to use that saving tree in the another function outside the class.when i asked to print saving_tree it printing but,only for that instance.i want the saving_tree{} to have the data to store data of all instance and access it outside. when i asked for print saving_tree outside the class it prints empty{}.. please tell me the required modification to get my required output and use saving_tree{} outside the class..

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  • Dynamic proxies to auto-save models

    - by atomman
    I'm trying to make some auto-magic happen in java using proxies to track objects and saving them when a set* method is called. I started of using java's built in Proxy, and everything works just fine, but from what I can understand I need a interface for every model, which is something that I'm trying to avoid. This is where CGLIB comes in, it allows me to create proxies of my models without the use of interfaces. BUT, how can I now retrieve the original object, the one I am trying to save? The optimal solution to be would be something like the EntityManager interface used by hibernate, where you keep your original object, but it is still tracked.

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  • Why does coffeescript generate classes like this?

    - by ryeguy
    Given the following coffeescript code: class Animal constructor: (@name) -> speak: (things) -> "My name is #{@name} and I like #{things}" This is generated: var Animal = (function() { function Animal(name) { this.name = name; } Animal.prototype.speak = function(things) { return "My name is " + this.name + " and I like " + things; }; return Animal; })(); But why isn't this more idiomatic code generated? var Animal = function Animal(name) { this.name = name; }; Animal.prototype.speak = function(things) { return "My name is " + this.name + " and I like " + things; }; I know that coffeescript wraps a lot of stuff in anonymous functions to control scope leak, but what could leak here?

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  • Obj-C Sending Messages Between Classes

    - by user544359
    I'm a newbie in iPhone Programming. I'm trying to send a message from one view controller to another. The idea is that viewControllerA takes information from the user and sends it to viewControllerB. viewControllerB is then supposed to display the information in a label. viewControllerA.h #import <UIKit/UIKit.h> @interface viewControllerA : UIViewController { int num; } -(IBAction)do; @end viewControllerA.m #import "viewControllerA.h" #import "viewControllerB.h" @implementation viewControllerA - (IBAction)do { //initializing int for example num = 2; viewControllerB *viewB = [[viewControllerB alloc] init]; [viewB display:num]; [viewB release]; //viewA is presented as a ModalViewController, so it dismisses itself to return to the //original view, i know it is not efficient [self dismissModalViewControllerAnimated:YES]; } - (void)dealloc { [super dealloc]; } @end viewControllerB.h #import <UIKit/UIKit.h> @interface viewControllerB : UIViewController { IBOutlet UILabel *label; } - (IBAction)openA; - (void)display:(NSInteger)myNum; @end viewControllerB.m #import "viewControllerB.h" #import "viewControllerA.h" @implementation viewControllerB - (IBAction)openA { //presents viewControllerA when a button is pressed viewControllerA *viewA = [[viewControllerA alloc] init]; [self presentModalViewController:viewA animated:YES]; } - (void)display:(NSInteger)myNum { NSLog(@"YES"); [label setText:[NSString stringWithFormat:@"%d", myNum]]; } @end YES is logged successfully, but the label's text does not change. I have made sure that all of my connections in Interface Builder are correct, in fact there are other (IBAction) methods in my program that change the text of this very label, and all of those other methods work perfectly... Any ideas, guys? You don't need to give me a full solution, any bits of information will help. Thanks.

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  • [Android] Putting Serializable Classes into SQL?

    - by CaseyB
    Here's the situation. I have a bunch of objects that implement Serializable that I want to store in a SQL database. I have two questions Is there a way to serialize the object directly into the database Is that the best way to do it or should I Write the object out to a formatting String and put it in the database that way and then parse it back out Write each member to the database with a field that is unique to each object

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  • jquery(selector) how to select the last element from two different classes

    - by Yasir Laghari
    for the following html <div> <div class="col1" > I dont want to select this </div> <div class="col2"> I dont want to select this </div> <div class="col1"> I dont want to select this </div> <div class="col1"> I dont want to select this </div> <div class="col2"> I WANT to select this </div> </div> How do I select the last element with two different class names? Tried using $("col1:last,col2:last) but it gives back 2 elements tried $("col1,col2:last") and this gives all col1 and last of col2

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  • Does [Serializable] work for inherited classes?

    - by MattiasK
    I haven't worked much with remoting so excuse this rather rudimentary question, If I derive a class from an abstract class marked as [Serializable] (for passing the data across an appdomain), does the other side get the actual overriden implementation? ie does polymorphism work over remoting/Serializable? I need to create a clone on the other side rather than operating on the original so MarshalByRef is not an option...

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  • c++ design question: Can i query the base classes to find the number of derived classes satisfying a

    - by vivekeviv
    I have a piece of code like this class Base { public: Base(bool _active) { active = _active; } void Configure(); void Set Active(bool _active); private: bool active; }; class Derived1 : public Base { public: Derived1(bool active):Base(active){} }; similarly Derived 2 and Derived 3 Now if i call derived1Object.Configure, i need to check how many of the derived1Obj, derived2Obj,derived3Obj is active. Should i add this in the "Base" class like a function say, GetNumberOfActive()? And If the implementation is like this: class Imp { public: void Configure() { //Code instantiating a particular Derived1/2/3 Object int GetNumberOfActiveDerivedObj(); baseRef.Configure(int numberOfActiveDerivedClasses); } prive: Derived1 dObj1(true); Derived2 dObj2(false); Derived3 dObj3(true); }; should i calculate the numberOfActive Derived Objects in Imp Class? THanks

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  • Do classes which have a vector has a member have memory issues

    - by user263766
    I am just starting out C++, so sorry if this is a dumb question. I have a class Braid whose members are vectors. I have not written an assignment operator. When I do a lot of assignments to an object of the type Braid, I run into memory issues :- 0 0xb7daff89 in _int_malloc () from /lib/libc.so.6 #1 0xb7db2583 in malloc () from /lib/libc.so.6 #2 0xb7f8ac59 in operator new(unsigned int) () from /usr/lib/libstdc++.so.6 #3 0x0804d05e in __gnu_cxx::new_allocator<int>::allocate (this=0xbf800204, __n=1) at /usr/lib/gcc/i686-pc-linux-gnu/4.4.3/../../../../include/c++/4.4.3/ext/new_allocator.h:89 #4 0x0804cb0e in std::_Vector_base<int, std::allocator<int> >::_M_allocate (this=0xbf800204, __n=1) at /usr/lib/gcc/i686-pc-linux-gnu/4.4.3/../../../../include/c++/4.4.3/bits/stl_vector.h:140 #5 0x0804c086 in _Vector_base (this=0xbf800204, __n=1, __a=...) at /usr/lib/gcc/i686-pc-linux-gnu/4.4.3/../../../../include/c++/4.4.3/bits/stl_vector.h:113 #6 0x0804b4b7 in vector (this=0xbf800204, __x=...) at /usr/lib/gcc/i686-pc-linux-gnu/4.4.3/../../../../include/c++/4.4.3/bits/stl_vector.h:242 #7 0x0804b234 in Braid (this=0xbf800204) at braid.h:13 #8 0x080495ed in Braid::cycleBraid (this=0xbf8001b4) at braid.cpp:191 #9 0x080497c6 in Braid::score (this=0xbf800298, b=...) at braid.cpp:251 #10 0x08049c46 in Braid::evaluateMove (this=0xbf800468, move=1, pos=0, depth=2, b=...) I suspect that these memory issues are because the vectors are getting resized. What I want to know is whether objects of type Braid automatically expand when its members expand? he code I am writing is really long so I will post the section which is causing the problems. Here is the relevant section of the code :- class Braid { private : vector<int> braid; //Stores the braid. int strands; vector < vector<bool> > history; vector < vector<bool> > CM; public : Braid () : strands(0) {} Braid operator * (Braid); Braid* inputBraid(int,vector<int>); int printBraid(); int printBraid(vector<vector<int>::iterator>); vector<int>::size_type size() const; ..... ..... } Here is the function which causes the issue :- int Braid::evaluateMove(int move,int pos,int depth,Braid b) { int netscore = 0; Braid curr(*this); curr = curr.move(move,pos); netscore += curr.score(b); while(depth > 1) { netscore += curr.evaluateMove(1,0,depth,b); netscore += curr.evaluateMove(2,0,depth,b); for(int i = 0; i < braid.size();++i) { netscore += curr.evaluateMove(3,i,depth,b); netscore += curr.evaluateMove(4,i,depth,b); netscore += curr.evaluateMove(5,i,depth,b); curr = curr.cycleBraid(); netscore += curr.evaluateMove(6,0,depth,b); } --depth; } return netscore; }

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  • Adding variably named fields to Python classes

    - by Carson Myers
    I have a python class, and I need to add an arbitrary number of arbitrarily long lists to it. The names of the lists I need to add are also arbitrary. For example, in PHP, I would do this: class MyClass { } $c = new MyClass(); $n = "hello" $c.$n = array(1, 2, 3); How do I do this in Python? I'm also wondering if this is a reasonable thing to do. The alternative would be to create a dict of lists in the class, but since the number and size of the lists is arbitrary, I was worried there might be a performance hit from this. If you are wondering what I'm trying to accomplish, I'm writing a super-lightweight script interpreter. The interpreter walks through a human-written list and creates some kind of byte-code. The byte-code of each function will be stored as a list named after the function in an "app" class. I'm curious to hear any other suggestions on how to do this as well.

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  • [iphone] method created in a seperate class returns "out of scope"

    - by Dror Sabbag
    Hey, I have created a Class (subclass of NSObject) which will hold all my SQLs/dbConnections etc.. in a seperate viewcontroller, i have instantiated the SQL's class and performed some actions, all went trough OK. but. one of my methods in the SQL's class is a method defined as follows: -(NSString *)queryTable:(NSUInteger *)fieldnum //query from db, and assign the field value into "fieldName" dbEntity = fieldName; [fieldName release]; } sqlite3_finalize(statement); } return dbEntity; } dbEntity is defined as NSString, and i have set it as a nonatoimc-retain property @property (nonatomic,retain) NSString *dbEntity; when ever i call this method out from my viewController and debug step by step, i see that the method is running, it is quering from the db as expected, but when it passes the value into dbEntity the values in dbEntity are suddenly "out of scope" that is... if i browse this specific action: dbEntity = fieldName; i can see values inside fieldName, but see "out of scope" in dbEntity. Why is that?!? what is wrong with dbEntity definitions? Any help will be appriciated.

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  • fluent nhibernate - storing and retrieving three classes in/from one table

    - by Will I Am
    Noob question. I have this situation where I have these objects: class Address { string Street; string City; ... } class User { string UserID; Address BillingAddress; Address MailingAddress; ... } What is the proper way of storing this data using (fluent) nHibernate? I could use a separate Address table and create a reference, but they are 1:1 relationships so I don't really want to incur the overhead of a join. Ideally I would store this as a single flat record. So, my question is, what is the proper way of storing an instance of class 'User' in such a way that it stores its contents and also the two addresses as a single record? My knowledge is failing me on how I can store this information in such a way that the two Address records get different column names (e.g. BillingAddress_Street and MailingAddress_Street, for example), and also how to read a record back into a User instance.

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  • Using Classes / OOP in PHP

    - by Alex Demchak
    I'm pretty proficient with PHP, outside of OOP - which I am just now starting to jump in to. I've been watching videos and reading tutorials, but they are all still pretty confusing... If I have FILE 1 (class.time.php) class Time { function GetTime(){ $time = date('H:i:s'); printf($time); } } and then in a nother php page I've got FILE 2 (page.php) I can do include('class.time.php'); and then anywhere in this page I can then do $time = new Time; //Calling the class and setting the class to a variable $time->GetTime(); //This is BASICALLY saying (run the 'GetTime' function in the 'Time Class' My main question is, is the comment above (This is BASICALLY saying.....) correct? or is there a better way to think of it?

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  • Passing a NSString to another ViewController using classes

    - by Jeff Kranenburg
    I know this insanely simple, but I am re-teaching myself the basics and trying to get my head around this:-) I have one ViewController called MainVC and I have one called ClassVC In ClassVC I have this code: @interface ClassVC : UIViewController { NSString *mainLine; } @property (nonatomic, retain) NSString *mainLine; @end and I have this in the implementation file: @synthesize mainLine = _mainLine; -(NSString *)_mainLine { _mainLine = @"This a string from a Class"; return _mainLine; } Now I was thinking that if I #import the ClassVC into MainVC I would be able to transfer that string along as well like so: This code is in the viewDidLoad _mainLabel.text = _secondClass.mainLine; NSLog(@"%@", _secondClass.mainLine); But that is not working - so cannot I not pass strings in through this way???

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  • Force to reimplement a static function in inherit classes

    - by pacopepe
    Hi, I have a program in C++ with plugins (dynamic libs). In the main program, I want to execute a static function to check if i can create a object of this type. An example without dynamic libs (aren't neccesary to understand the problem): #include "libs/parent.h" #include "libs/one.h" #include "libs/two.h" int main(int argc, char * argv[]) { Parent obj; if (One.match(argv[1])) { obj = new One(); else if (Two.match(argv[1])) { obj = new Two(); } Now, i have a interface class named Parent. All plugins inherit from this class. Ideally, I have a virtual static function in Parent named match, and all the plugins need to reimplement this function. The problem with this code is that i can't do a static virtual function in C++, so i don't know how to solve the problem. Sorry for mi english, i did my best

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  • how to organize classes in ruby if they are literal subclasses

    - by RetroNoodle
    I know that title didn't make sense, Im sorry! Its hard to word what I am trying to ask. I had trouble googling it for the same reason. So this isn't even Ruby specific, but I am working in ruby and I am new to it, so bear with me. So you have a class that is a document. Inside each document, you have sentences, and each sentence has words. Words will have properties, like "noun" or a count of how many times they are used in the document, etc. I would like each of the elements, document, sentence, word be an object. Now, if you think literally - sentences are in documents, and words are in sentences. Should this be organized literally like this as well? Like inside the document class you will define and instantiate the sentence objects, and inside the sentence class you will define and instantiate the words? Or, should everything be separate and reference each other? Like the word class would sit outside the sentence class but the sentence class would be able to instantiate and work with words? This is a basic OOP question I guess, and I suppose you could argue to do it either way. What do you guys think? Each sentence in the document could be stored in a hash of sentence objects inside the document object, and each word in the sentence could be stored in a hash of word objects inside the sentence. I dont want to code myself into a corner here, thats why I am asking, plus I have wondered this before in other situations. Thank you!

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  • What happens when you create an instance of an object containing no state in C#?

    - by liquorice
    I am I think ok at algorithmic programming, if that is the right term? I used to play with turbo pascal and 8086 assembly language back in the 1980s as a hobby. But only very small projects and I haven't really done any programming in the 20ish years since then. So I am struggling for understanding like a drowning swimmer. So maybe this is a very niave question or I'm just making no sense at all, but say I have an object kind of like this: class Something : IDoer { void Do(ISomethingElse x) { x.DoWhatEverYouWant(42); } } And then I do var Thing1 = new Something(); var Thing2 = new Something(); Thing1.Do(blah); Thing2.Do(blah); does Thing1 = Thing2? does "new Something()" create anything? Or is it not much different different from having a static class, except I can pass it around and swap it out etc. Is the "Do" procedure in the same location in memory for both the Thing1(blah) and Thing2(blah) objects? I mean when executing it, does it mean there are two Something.Do procedures or just one?

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  • Ruby on Rails: Modules vs. Classes

    - by Jack
    I'm trying to add a function that will be accessible throughout all parts of my program. I want something like: def GlobalFunctions.my_function(x,y) puts x + y end to be accessible for all models. Specifically I am trying to use a function like this in my seeds.rb file but I am most likely going to be reusing the code and don't want any redundancy. Now I know I can make a simple class, but I could also make a module. What are some reasons to go in either direction? And once I've decided on which type to use, how do I make it accessible throughout the whole program? I have tried a module, but I keep getting " Expected app/[module file] to define [ModuleName]"

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  • How to declare different non-JPA annotations on embedded classes

    - by e99y
    @Embedded public class EmbedMe { private String prop1; private String prop2; } @Entity public class EncryptedEmbedded { @Embeddable private EmbedMe enc; } I am current using Jasypt for encryption. Is there a way to indicate that the @Embeddable in EncryptedEmbedded will use @Type(value = "newDeclaredTypeHere") per attribute (prop1, prop2)? Thanks in advance... ;)

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  • How classes are secure than structures ?

    - by Asad Hanif
    Structure's member are public by default ans class's members are private by default. We can access private data members through a proper channel (using member function). If we have access to member functions we can read/write data in private data member, so how it is secure...we are accessing it and we are changing data too.....

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  • Automatically Add a Prefix to Column Names for @Embeddable Classes

    - by VeeArr
    I am developing a project in which I am persisting some POJOs by adding Hibernate annotations. One problem I am running into is that code like this fails, as Hibernate tries to map the sub-fields within the Time_T onto the same column (i.e. startTime.sec and stopTime.sec both try to map to the colum sec, causing an error). @Entity public class ExampleClass { @Id long eventId; Time_T startTime; Time_T stopTime; } @Embeddable public class Time_T { int sec; int nsec; } As there will be many occurrences like this throughout the system, it would be nice if there was an option to automatically append a prefix to the column name (e.g. make the columns be startTime_sec, startTime_nsec, stopTime_sec, stopTime_nsec), without having to apply overrides on a per-field basis. Does Hibernate have this capability, or is there any other reasonable work-around?

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  • Operator as and generic classes

    - by abatishchev
    I'm writing .NET On-the-Fly compiler for CLR scripting and want execution method make generic acceptable: object Execute() { return type.InvokeMember(..); } T Execute<T>() { return Execute() as T; /* doesn't work: The type parameter 'T' cannot be used with the 'as' operator because it does not have a class type constraint nor a 'class' constraint */ // also neither typeof(T) not T.GetType(), so on are possible return (T) Execute(); // ok } But I think operator as will be very useful: if result type isn't T method will return null, instead of an exception! Is it possible to do?

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  • jquery switch element classes

    - by Sobakinet
    Please take a look here: http://jsfiddle.net/ZUd27/7/ What I need: There are several elements. One of them is active and visible. If I hover over any inactive element, it becomes visible and active. The previously active element becomes inactive. On mouseout, nothing happens - the last hovered element stays active. My problems: The first active element always stays active (in DOM?). It becomes invisible, but on next mouseover nothing happens. Other elements don't behave as they should. If one of them is active, on next mousein it becomes invisible. thx

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