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  • How to know if a std::list has been modified

    - by Nick
    I have this class: class C { public: C* parent; std::list<C> children; }; I can use this class in this way for example: C root; C child; root.children.push_back(child); // or other method of std::list (es: push_front, insert, ...) // Here child.parent is root // How can I set the parent of child? I want to do this work internally to my class without losing the functionality of std::list, is it possible?

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  • How can I get model names from inside my app?

    - by Cameron
    I have a bunch of models in a sub-directory that inherit from a model in the models root directory. I want to be able to set a class variable in another model that lists each inherited model class. i.e @@groups = sub_models.map do { |model| model.class.to_s } Not sure how to get at this info though...

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  • How to save to two tables using one SQLAlchemy model

    - by Oatman
    I have an SQLAlchemy ORM class, linked to MySQL, which works great at saving the data I need down to the underlying table. However, I would like to also save the identical data to a second archive table. Here's some psudocode to try and explain what I mean my_data = Data() #An ORM Class my_data.name = "foo" #This saves just to the 'data' table session.add(my_data) #This will save it to the identical 'backup_data' table my_data_archive = my_data my_data_archive.__tablename__ = 'backup_data' session.add(my_data_archive) #And commits them both session.commit() Just a heads up, I am not interested in mapping a class to a JOIN, as in: http://www.sqlalchemy.org/docs/05/mappers.html#mapping-a-class-against-multiple-tables

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  • Hibernate not loading associated object

    - by Noor
    Hi, i am trying to load a hibernate object ForumMessage but in it contain another object Users and the Users object is not being loaded. My ForumMessage Mapping File: <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Jan 4, 2011 10:10:29 AM by Hibernate Tools 3.4.0.Beta1 --> <hibernate-mapping> <class name="com.BiddingSystem.Models.ForumMessage" table="FORUMMESSAGE"> <id name="ForumMessageId" type="long"> <column name="FORUMMESSAGEID" /> <generator class="native" /> </id> <property name="ForumMessage" type="java.lang.String"> <column name="FORUMMESSAGE" /> </property> <many-to-one name="User" class="com.BiddingSystem.Models.Users" fetch="join"> <column name="UserId" /> </many-to-one> <property name="DatePosted" type="java.util.Date"> <column name="DATEPOSTED" /> </property> <many-to-one name="Topic" class="com.BiddingSystem.Models.ForumTopic" fetch="join"> <column name="TopicId" /> </many-to-one> </class> </hibernate-mapping> and I am using the follwing code: Session session = gileadHibernateUtil.getSessionFactory().openSession(); SQL="from ForumMessage"; System.out.println(SQL); Query query=session.createQuery(SQL); System.out.println(query.list().size()); return new LinkedList <ForumMessage>(query.list());

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  • How can I map a String to a function in Java?

    - by Bears will eat you
    Currently, I have a bunch of Java classes that implement a Processor interface, meaning they all have a processRequest(String key) method. The idea is that each class has a few (say, <10) member Strings, and each of those maps to a method in that class via the processRequest method, like so: class FooProcessor implements Processor { String key1 = "abc"; String key2 = "def"; String key3 = "ghi"; // and so on... String processRequest(String key) { String toReturn = null; if (key1.equals(key)) toReturn = method1(); else if (key2.equals(key)) toReturn = method2(); else if (key3.equals(key)) toReturn = method3(); // and so on... return toReturn; } String method1() { // do stuff } String method2() { // do other stuff } String method3() { // do other other stuff } // and so on... } You get the idea. This was working fine for me, but now I need a runtime-accessible mapping from key to function; not every function actually returns a String (some return void) and I need to dynamically access the return type (using reflection) of each function in each class that there's a key for. I already have a manager that knows about all the keys, but not the mapping from key to function. My first instinct was to replace this mapping using if-else statements with a Map<String, Function>, like I could do in Javascript. But, Java doesn't support first-class functions so I'm out of luck there. I could probably dig up a third-party library that lets me work with first-class functions, but I haven't seen any yet, and I doubt that I need an entire new library. I also thought of putting these String keys into an array and using reflection to invoke the methods by name, but I see two downsides to this method: My keys would have to be named the same as the method - or be named in a particular, consistent way so that it's easy to map them to the method name. This seems WAY slower than the if-else statements I have right now. Efficiency is something of a concern because these methods will tend to get called pretty frequently, and I want to minimize unnecessary overhead. TL; DR: I'm looking for a clean, minimal-overhead way to map a String to some sort of a Function object that I can invoke and call (something like) getReturnType() on. I don't especially mind using a 3rd-party library if it really fits my needs. I also don't mind using reflection, though I would strongly prefer to avoid using reflection every single time I do a method lookup - maybe using some caching strategy that combines the Map with reflection. Thoughts on a good way to get what I want? Cheers!

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  • What else I must do allow my method to handle any type of objects

    - by NewHelpNeeder
    So to allow any type object I must use generics in my code. I have rewrote this method to do so, but then when I create an object, for example Milk, it won't let me pass it to my method. Ether there's something wrong with my generic revision, or Milk object I created is not good. How should I pass my object correctly and add it to linked list? This is a method that causes error when I insert an item: public void insertFirst(T dd) // insert at front of list { Link newLink = new Link(dd); // make new link if( isEmpty() ) // if empty list, last = newLink; // newLink <-- last else first.previous = newLink; // newLink <-- old first newLink.next = first; // newLink --> old first first = newLink; // first --> newLink } This is my class I try to insert into linked list: class Milk { String brand; double size; double price; Milk(String a, double b, double c) { brand = a; size = b; price = c; } } This is test method to insert the data: public static void main(String[] args) { // make a new list DoublyLinkedList theList = new DoublyLinkedList(); // this causes: // The method insertFirst(Comparable) in the type DoublyLinkedList is not applicable for the arguments (Milk) theList.insertFirst(new Milk("brand", 1, 2)); // insert at front theList.displayForward(); // display list forward theList.displayBackward(); // display list backward } // end main() } // end class DoublyLinkedApp Declarations: class Link<T extends Comparable<T>> {} class DoublyLinkedList<T extends Comparable<T>> {}

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  • Is call to function object inlined?

    - by dehmann
    In the following code, Foo::add calls a function via a function object: struct Plus { inline int operator()(int x, int y) const { return x + y; } }; template<class Fct> struct Foo { Fct fct; Foo(Fct f) : fct(f) {} inline int add(int x, int y) { return fct(x,y); // same efficiency adding directly? } }; Is this the same efficiency as calling x+y directly in Foo::add? In other words, does the compiler typically directly replace fct(x,y) with the actual call, inlining the code, when compiling with optimizations enabled?

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  • jquery: .attr() fails for child element

    - by user984003
    I'm going crazy staring at this. I need to change the attribute of an element, something which I have done many times before. But it fails. Now I can't even get jquery to show me the attribute that it has. Does it have to do with what is returned by find()? var c = new_photo_div.find('[class = photo]')[0]; alert(c); alert(new_photo_div.attr('class')); alert(c.attr('class')); The first alert correctly identifies the element: Object HTMLImageElement The second alert correctly gives me the class of new_photo_div. The third alert fails. No alert. I think it should say: photo

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  • Resolve circular typedef dependency?

    - by Nick
    What is the best way to resolve the following circular dependency in typedef-ing these structs? Note the C language tag - I'm looking for a solution in standard gcc C. typedef struct { char* name; int age; int lefthanded; People* friends; } Person; typedef struct { int count; int max; Person* data; } People;

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  • Do I always need to rebuild the project containing references to sub project's dll, if sub projects

    - by Puneet Dudeja
    I have a solution containing 4 class library projects and one "web site" project. The web site project contains references to the 3 class library projects, whenever I make changes in any of the class library projects, the only option I see is to rebuild the web site which takes a lot of time. Is there any option that I can only update the dll references and the changes are reflected in the web site project ?

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  • Serializing an extended form object

    - by andyperfect
    I've been reading up on this whole subject, but I never came across this specific problem. I already understand that the whole idea of serializing an entire form is a horrible idea and just doesn't work. But, I am encountering a bit of a different problem. I have a class that inherits the "button" form object, that I call DataButton. Now for my problem. I want to be able to serialize this class, but I don't need any of the information from the actual button class. Is there any way to bypass the fact that I can't set the button form object to Serializable() and notify VB that when serialization is to occur, it should simply skip over that information? Theoretically, if such a procedure were possible, I'd be able to do the entire serialization without a hitch. I came up with the idea earlier of removing the "inherits" feature from the class, and having simply a button within the class, but that makes my program really difficult to work with as I am constantly changing the location, size, backgroundImage, text, and whatnot. Thus, immediate updates would be much tougher to work with. Any help would be greatly appreciated.

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  • Debug.writeline locks

    - by Carra
    My program frequently stops with a deadlock. When I do a break-all and look at the threads I see that three threads are stuck in our logging function: public class Logging { public static void WriteClientLog(LogLevel logLevel, string message) { #if DEBUG System.Diagnostics.Debug.WriteLine(String.Format("{0} {1}", DateTime.Now.ToString("HH:mm:ss"), message)); //LOCK #endif //...Log4net logging } } If I let the program continue the threads are still stuck on that line. I can't see where this can lock. The debug class, string class & datetime class seem to be thread safe. The error goes away when I remove the "#if DEBUG System... #endif" code but I'm curious why this behavior happens. Thread one: public void CleanCache() { Logging.WriteClientLog(LogLevel.Debug, "Start clean cache.");//Stuck } Thread two: private void AliveThread() { Logging.WriteClientLog(LogLevel.Debug, "Check connection");//Stuck }

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  • Expected symbol problems with this function declaration

    - by Derek
    I am just getting back into the C programming realm and I am having an issue that I think is linker related. I am using cmake for the first time as well, so that could be adding to my frustration. I have included a third party header file that contains a typedef that my code is trying to use, and it has this line: typedef struct a a_t so my code has a_t *var; //later..... var->member;// this line throws the error which throws the error: dereferencing pointer to incomplete type So am I just missing another include file, or is this a linker issue? I am building this code in QtCreator and using cmake. I can dive on a_t to see that typedef declaration in the included header, but I can't seem to dive on "struct a" itself to see where it's coming from. Thanks

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  • STI and accepts_nested_attributes_for in rails

    - by ryanshackintosh
    I have models as follows: class Entity < ActiveRecord::Base has_many :addresses accepts_nested_attributes_for :addresses, :reject_if => lambda { |a| a[:label].blank?} , :allow_destroy => true end class Client < Entity before_save :set_type private def set_type self.type = "Client" end end class Address < ActiveRecord::Base belongs_to :entity end I have recently implemented accepts_nested_attributes_for on the /clients/new form, as follows: <% form_for(@client, :html => {:class => 'form'}) do |f| -%> <%= f.label :name %> <%= f.text_field :name -%> <%= f.label :phone %> <%= f.text_field :phone %> <% f.fields_for :addresses do |a| %> <%= a.label :street %> <%= a.text_field :street%> <%= a.label :city %> <%= a.text_field :city %> <% end %> <% end %> And my controller as follows: class ClientsController < ApplicationController before_filter :load_client , :except => [:index, :new, :create, :render_clients] def new @client = Client.new @client.addresses.build end def create @client = Client.new(params[:client]) if @client.save flash[:notice] = 'Client has been successfully added' redirect_to @client else render :action => 'new' end end The issue is that when the record is saved it gives an error stating: "Entity can't be blank" I assume it is something to do with the fact that a 'Client' and not an 'Entity' is being added. Can anyone point me in the right direction?

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  • Protect value from changies using reflection?

    - by IordanTanev
    Hi, here is the problem case i am writing a little third party library. In this library i have a class like this public class TestClass { public int TestField { get; private set; } public TestClass( ) { TestField = 1; } } Then i have a varialbe form this class like this public TestClass test = new TestClass( ); The problem i am facing is that usnig reflection like this PropertyInfo field = typeof( TestClass ).GetProperty( "TestField" ); field.SetValue( test, 2, null ); programers can change internal value of this class. this will be very bad thing becouse it can crash the hole library. My question is what is the best way to protect my code form such changes.I know i can use some kind of bool flag so tha value can be changed only ones but this is not very good salution is there a better one? Best Regards, Iordan

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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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  • connecting to multiple resources

    - by Dudu
    I would like to know if there is a way to connect to multiple resources: Specifically I have the following problem abstact class BaseClass { ObservableCollection<BaseClass>; } class GrandSonClass:BaseClass{} class SonClass:BaseClass{} class FatherClass:BaseClass { CollectionViewSource col = new CollectionViewSource ; col.Source = Items.SelectMany(p => p.Items); } FatherClass's Items are of ChildrenClass type, and ChildrenClass's Items are of GrandSonClass type; I want FatherClass to bind to all the GrandSonClass's items it possesses. The solution of using SelectMany is not good as I need this to be dynamically updated whenever FatherClass adds more Items and whenever its Items(SonClasses) add more Items. Now I could go on and write notifiaction events but I was wondering if there is a smarter way to do it -i.e. simply define the sources as the Items of each Item FatherClass posses

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  • C# Constructor Problem When Using Generics

    - by Jimbo
    Please see an example of my code below: public class ScrollableCheckboxList { public List<ScrollableCheckboxItem> listitems; public void ScrollableCheckboxList<TModel>(IEnumerable<TModel> items, string valueField, string textField, string titleField) where TModel : class { listitems = new List<ScrollableCheckboxItem>(); foreach (TModel item in items) { Type t = typeof(TModel); PropertyInfo[] props = new [] { t.GetProperty(textField), t.GetProperty(valueField), t.GetProperty(titleField) }; listitems.Add(new ScrollableCheckboxItem { text = props[0].GetValue(item, null).ToString(), value = props[1].GetValue(item, null).ToString(), title = props[2].GetValue(item, null).ToString() }); } } } The code produces the following error: 'ScrollableCheckboxList': member names cannot be the same as their enclosing type This clearly means that there is a method in the class that has the same name as the class, but usually insinuates that the method is trying to return something (which is not allowed) In my case, all I have done is declare a constructor - why would this be a problem?

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  • C#: Determine Type for (De-)Serialization

    - by dbemerlin
    Hi, i have a little problem implementing some serialization/deserialization logic. I have several classes that each take a different type of Request object, all implementing a common interface and inheriting from a default implementation: This is how i think it should be: Requests interface IRequest { public String Action {get;set;} } class DefaultRequest : IRequest { public String Action {get;set;} } class LoginRequest : DefaultRequest { public String User {get;set;} public String Pass {get;set;} } Handlers interface IHandler<T> { public Type GetRequestType(); public IResponse HandleRequest(IModel model, T request); } class DefaultHandler<T> : IHandler<T> // Used as fallback if the handler cannot be determined { public Type GetRequestType() { return /* ....... how to get the Type of T? ((new T()).GetType()) ? .......... */ } public IResponse HandleRequest(IModel model, T request) { /* ... */ } } class LoginHandler : DefaultHandler<LoginRequest> { public IResponse HandleRequest(IModel mode, LoginRequest request) { } } Calling class Controller { public ProcessRequest(String action, String serializedRequest) { IHandler handler = GetHandlerForAction(action); IRequest request = serializer.Deserialize<handler.GetRequestType()>(serializedRequest); handler(this.Model, request); } } Is what i think of even possible? My current Solution is that each handler gets the serialized String and is itself responsible for deserialization. This is not a good solution as it contains duplicate code, the beginning of each HandleRequest method looks the same (FooRequest request = Deserialize(serializedRequest); + try/catch and other Error Handling on failed deserialization). Embedding type information into the serialized Data is not possible and not intended. Thanks for any Hints.

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  • Where do you put non-controller classes in codeigniter?

    - by sprugman
    I've got a class Widgets. Widgets are made up of Doohickies. I'm never going to need to access Doohickies directly via url -- they're essentially a private class, only used by Widgets. Where do you put your code to define the Doohicky class? In /app/controllers/doohicky.php? in app/controllers/widget.php? somewhere else? Obviously, the former seems cleaner, but it's not obvious to me how to make the Doohicky class available to Widget.

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  • How do I replace "this" in Java with something that works.

    - by Luke Alderton
    I'm looking to get the showGUI() method work, the compiler says "this" is not a static variable and cannot be referenced from a static context, what would I use to replace "this"? I've tried test.main (test being the package it's in). The reason I'm using the static method showGUI() is because I need the method to be called from another static method, as well as the startup() method. Below are my two main classes. public class Main extends SingleFrameApplication { @Override protected void startup() { showGUI(); } @Override protected void configureWindow(java.awt.Window root) { } public static Main getApplication() { return Application.getInstance(Main.class); } public static void main(String[] args) { launch(Main.class, args); } public static void showGUI() { show(new GUI(this)); } } public class GUI extends FrameView { public GUI(SingleFrameApplication app) { super(app); initComponents(); } private void initComponents() { //all the GUI stuff is somehow defined here } }

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  • Why does the VS2005 debugger not report "base." values properly? (was "Why is this if statement fail

    - by Rawling
    I'm working on an existing class that is two steps derived from System.Windows.Forms.Combo box. The class overrides the Text property thus: public override string Text { get { return this.AccessibilityObject.Value; } set { if (base.Text != value) { base.Text = value; } } } The reason given for that "get" is this MS bug: http://support.microsoft.com/kb/814346 However, I'm more interested in the fact that the "if" doesn't work. There are times where "base.Text != value" is true and yet pressing F10 steps straight to the closing } of the "set" and the Text property is not changed. I've seen this both by just checking values in the debugger, and putting a conditional breakpoint on that only breaks when the "if" statement's predicate is true. How on earth can "if" go wrong? The class between this and ComboBox doesn't touch the Text property. The bug above shouldn't really be affecting anything - it says it's fixed in VS2005. Is the debugger showing different values than the program itself sees? Update I think I've found what is happening here. The debugger is reporting value incorrectly (including evaluating conditional breakpoints incorrectly). To see this, try the following pair of classes: class MyBase { virtual public string Text { get { return "BaseText"; } } } class MyDerived : MyBase { public override string Text { get { string test = base.Text; return "DerivedText"; } } } Put a breakpoint on the last return statement, then run the code and access that property. In my VS2005, hovering over base.Text gives the value "DerivedText", but the variable test has been correctly set to "BaseText". So, new question: why does the debugger not handle base properly, and how can I get it to?

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  • Scope of Groovy's ExpandoMetaClass?

    - by TicketMonster
    Groovy exposes an ExpandoMetaClass that allows you to dynamically add instance and class methods/properties to a POJO. I would like to use it to add an instance method to one of my Java classes: public class Fizz { // ...etc. } Fizz fizz = new Fizz(); fizz.metaClass.doStuff = { String blah -> fizz.buzz(blah) } This would be the equivalent to refactoring the Fizz class to have: public class Fizz { // ctors, getters/setters, etc... public void doStuff(String blah) { buzz(blah); } } My question: Does this add doStuff(String blah) to only this particular instance of Fizz? Or do all instances of Fizz now have a doStuff(String blah) instance method? If the former, how do I get all instances of Fizz to have the doStuff instance method? I know that if I made the Groovy: fizz.metaClass.doStuff << { String blah -> fizz.buzz(blah) } Then that would add a static class method to Fizz, such as Fizz.doStuff(String blah), but that's not what I want. I just want all instances of Fizz to now have an instance method called doStuff. Ideas?

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  • How to get Ponter/Reference semantics in Scala.

    - by Lukasz Lew
    In C++ I would just take a pointer (or reference) to arr[idx]. In Scala I find myself creating this class to emulate a pointer semantic. class SetTo (val arr : Array[Double], val idx : Int) { def apply (d : Double) { arr(idx) = d } } Isn't there a simpler way? Doesn't Array class have a method to return some kind of reference to a particular field?

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