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  • How to override the attr_protected?

    - by KandadaBoggu
    I have STI implementation as follows: class Automobile < ActiveRecord::Base end class Car < Automobile end class Truck < Automobile end class User < ActiveRecord::Base has_many :automobiles accepts_nested_attributes_for :automobiles end I am creating a list of automobiles for a user. For each automobile, the UI sets the type field and the properties associated with the automobile.While form submission, the type field is ignored as it is a protected attribute. How do I work around this issue? Is there a declarative way to unprotect a protected attribute?

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  • Problem overridding virtual function

    - by William
    Okay, I'm writing a game that has a vector of a pairent class (enemy) that s going to be filled with children classes (goomba, koopa, boss1) and I need to make it so when I call update it calls the childclasses respective update. I have managed to create a example of my problem. #include <stdio.h> class A{ public: virtual void print(){printf("Hello from A");} }; class B : public A{ public: void print(){printf("Hello from B");} }; int main(){ A ab = B(); ab.print(); while(true){} } Output wanted: "Hello from B" Output got: "Hello from A" How do I get it to call B's print function?

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  • About calling an subclass' overriding method when casted to its superclass

    - by Omega
    #include <iostream> class Vehicle { public: void greet() { std::cout << "Hello, I'm a vehicle"; } }; class Car : public Vehicle { public: void greet() { std::cout << "Hello, I'm a car"; } }; class Bike : public Vehicle { public: void greet() { std::cout << "Hello, I'm a bike"; } }; void receiveVehicle(Vehicle vehicle) { vehicle.greet(); } int main() { receiveVehicle(Car()); return 0; } As you can see, I'm trying to send a parameter of type Vehicle to a function, which calls greet(). Car and Bike are subclasses of Vehicle. They overwrite greet(). However, I'm getting "Hello, I'm a vehicle". I suppose that this is because receiveVehicle receives a parameter of type Vehicle instead of a specific subclass like Car or Bike. But that's what I want: I want this function to work with any subclass of Vehicle. Why am I not getting the expected output?

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  • How to manage feeds with subclassed object in Django 1.2?

    - by Matteo
    Hi, I'm trying to generate a feed rss from a model like this one, selecting all the Entry objects: from django.db import models from django.contrib.sites.models import Site from django.contrib.auth.models import User from imagekit.models import ImageModel import datetime class Entry(ImageModel): date_pub = models.DateTimeField(default=datetime.datetime.now) author = models.ForeignKey(User) via = models.URLField(blank=True) comments_allowed = models.BooleanField(default=True) icon = models.ImageField(upload_to='icon/',blank=True) class IKOptions: spec_module = 'journal.icon_specs' cache_dir = 'icon/resized' image_field = 'icon' class Post(Entry): title = models.CharField(max_length=200) description = models.TextField() slug = models.SlugField(unique=True) def __unicode__(self): return self.title class Photo(Entry): alt = models.CharField(max_length=200) description = models.TextField(blank=True) original = models.ImageField(upload_to='photo/') class IKOptions: spec_module = 'journal.photo_specs' cache_dir = 'photo/resized' image_field = 'original' def __unicode__(self): return self.alt class Quote(Entry): blockquote = models.TextField() cite = models.TextField(blank=True) def __unicode__(self): return self.blockquote When I use the render_to_response in my views I simply call: def get_journal_entries(request): entries = Entry.objects.all().order_by('-date_pub') return render_to_response('journal/entries.html', {'entries':entries}) And then I use a conditional template to render the right snippets of html: {% extends "base.html" %} {% block main %} <hr> {% for entry in entries %} {% if entry.post %}[...]{% endif %}[...] But I cannot do the same with the Feed Framework in django 1.2... Any suggestion, please?

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  • A general declaration for all inherited classes

    - by Soham
    Consider, there is a class called SuperClass from which, ClassA, ClassB, ClassC is derived. From each one of those derived Classes, there are further more two classes are derived each called ChildClassAA and ChildClassAB[AB stands for Bth Child class from the Ath Class.Lets not really pull our hair on this nomenclature]. Now, ideally, I want to declare a general type as a private member of another Class say IndependentClass which can be initialized during run time as either of the objects of type ClassAor ClassB or ClassC and even the derived classes like ClassAA or ClassAB. Is there a possible way to do it?

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  • Forget late static binding, I need late static __FILE__ ...

    - by bobthecow
    I'm looking for the get_called_class() equivalent for __FILE__ ... Maybe something like get_included_file()? I have a set of classes which would like to know what directory they exist in. Something like this: <?php class A { protected $baseDir; public function __construct() { $this->baseDir = dirname(__FILE__); } public function getBaseDir() { return $this->baseDir; } } ?> And in some other file, in some other folder... <?php class B extends A { // ... } class C extends B { // ... } $a = new A; echo $a->getBaseDir(); $b = new B; echo $b->getBaseDir(); $c = new C; echo $c->getBaseDir(); // Annnd... all three return the same base directory. ?> Now, I could do something ghetto, like adding $this->baseDir = dirname(__FILE__) to each and every extending class, but that seems a bit... ghetto. After all, we're talking about PHP 5.3, right? Isn't this supposed to be the future? Is there another way to get the path to the file where a class was declared?

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  • Building drag and drop interface on iphone

    - by John Stewart
    I am trying to build an app which will have a bunch of cards that the user needs to drag and drop them onto specific drop zones. How would one go about detecting this and if the card is not on the drop zone then it should slide back. Any suggestions on how to structure this app?

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  • How to save derived type (TPT) in Entity Framework?

    - by Peter Stegnar
    I have problems with saving derived type (TPT) with Entity Framework to database. Let's say I have base entity Animal and derived type Dog. I want to save Dog entity. I thought that I could do it like contex.AddToDogs(), but contex contain only base entity - Animal. So I can only save Animal object - contex.AddToAnimals(). I have also tried with contex.AddObject("Animals", dogInstance), but I get the following error: The member with identity 'NavigationProperty' does not exist in the metadata collection. But I have add EntityReference to the "NavigationProperty". So how to save derived type in EF?

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  • How to link more than one object at a time in Xcode 4.2?

    - by Beppe
    I'm probably missing the basics here... Is there a way to link more than one object to a method at a time using Interface Builder in Xcode 4.2? I set tons of UIButtons in my UIView. All of them call just one method (let's say - (IBAction)buttonPushed:(UIButton *)aButton) that should do something different depending on the sender. I can't figure out a way to link them all with my method at a time. Any advice will be very appreciated... N.B. I'm using Xcode 4.2 on Snow Leopard, without storyboard.

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  • Javascript inherance and use of super: is this possible?

    - by Totty
    var Parent = function(value){ this.value = value; this.value1 = 3; this.hello = function(text){ alert(this.value1 + text); } } var Child = extends(Parent, function(value){ this.value1 = 1; this.hello = function(text){ this.super.hello(text); alert('Child' + this.value1 + this.value); } }) var child = new Child(2); child.hello('ola'); // this must output 2 alerts: // 1: "1ola" // 2: "Child1ola"

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  • ActiveRecord Validations for Models with has_many, belongs_to associations and STI

    - by keruilin
    I have four models: User Award Badge GameWeek The associations are as follows: User has many awards. Award belongs to user. Badge has many awards. Award belongs to badge. User has many game_weeks. GameWeek belongs to user. GameWeek has many awards. Award belongs to game_week. Thus, user_id, badge_id and game_week_id are foreign keys in awards table. Badge implements an STI model. Let's just say it has the following subclasses: BadgeA and BadgeB. Some rules to note: The game_week_id fk can be nil for BadgeA, but can't be nil for BadgeB. Here are my questions: For BadgeA, how do I write a validation that it can only be awarded one time? That is, the user can't have more than one -- ever. For BadgeB, how do I write a validation that it can only be awarded one time per game week?

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  • Does Qt support virtual pure slots ?

    - by ereOn
    Hi, My GUI project in Qt has a lot of "configuration pages" classes which all inherit directly from QWidget. Recently, I realized that all these classes share 2 commons slots (loadSettings() and saveSettings()). Regarding this, I have two questions: Does it make sense to write a intermediate base abstract class (lets name it BaseConfigurationPage) with these two slots as virtual pure methods ? (Every possible configuration page will always have these two methods, so I would say "yes") Before I do the heavy change in my code (if I have to) : does Qt support virtual pure slots ? Is there anything I should be aware of ? Here is a code example describing everything: class BaseConfigurationPage : public QWidget { // Some constructor and other methods, irrelevant here. public slots: virtual void loadSettings() = 0; virtual void saveSettings() = 0; }; class GeneralConfigurationPage : public BaseConfigurationPage { // Some constructor and other methods, irrelevant here. public slots: void loadSettings(); void saveSettings(); };

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  • .net, C# Interface between Business Logic and DAL

    - by Joel
    I'm working on a small application from scratch and using it to try to teach myself architecture and design concepts. It's a .NET 3.5, WPF application, and I'm using Sql Compact Edition as my data store. I'm working on the business logic layer, and have just now begun to write the DAL. I'm just using SqlCeComamnds to send over simple queries and SqlCeResultSet to get at the results. I'm starting to design my Insert and Update methods, and here's the issue - I don't know the best way to get the necessary data from the BLL into the DAL. Do I pass in a generic collection? Do I have a massive parameter list with all the data for the database? Do I simply pass in the actual business object (thus tying my DAL to the conrete stuff in the BLL?). I thought about using interfaces - simply passing IBusinessObjectA into the DAL, which provides the simplicity I'm looking for without tying me TOO tightly to current implementations. What do you guys think?

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  • Persisting non-entity class that extends an entity (jpa) - example?

    - by Michal Minicki
    The JPA tutorial states that one can have a non-entity that extends entity class: Entities may extend both entity and non-entity classes, and non-entity classes may extend entity classes. - http://java.sun.com/javaee/5/docs/tutorial/doc/bnbqa.html Is it possible to persist such structure? I want to do this: @Entity abstract class Test { ... } class FirstConcreteTest extends Test { ... } // Non-ntity class SecondConcreteTest extends Test { ... } // Non-entity Test test = new FirstConcreteTest(); em.persist(test); What I would like it to do is to persist all fields mapped on abstract Test to a common database table for all concrete classes (first and second), leaving all fields of first and second test class unpersisted (these can contain stuff like EJBs, jdbc pools, etc). And a bonus question. Is it possible to persist abstract property too? @Entity abstract class Test { @Column @Access(AccessType.PROPERTY) abstract public String getName(); } class SecondConcreteTest extends Test { public String getName() { return "Second Concrete Test"; } }

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  • Agile web development with Rails 4 interface difficulties

    - by Luke Annison
    I've been following along with the examples in the book in making a online catalog and am having a couple of discouraging difficulties in Chapter 8 task C: Catalog display. I have input the code for the stylesheets as instructed but it has created a slightly skewed result as compared to what is shown in the book. Whilst minor and aesthetic in nature its a little shock to my confidence and slightly irritating when trying to carry on through the book. I have too little rep to post a pic, but heres the link: http://s11.postimage.org/3pwlzfiwj/Screen_Shot_2012_10_08_at_22_29_56.png) As you can see the boarder seems a little confused and the image at the top is covering the header text. I've been through the code time and time again but can't seem find out where I've gone wrong. Could anybody give me some clues?

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  • Can this be done with multiple inhertance?

    - by Milo
    Here is what I would like to do. Say I have Class Widget. I then create Button from Widget. I then create ModifiedWidget which re-implements certain functions of Widget. I then want Button to use ModifiedWidget rather than plain Widget. Is this possible to do some how? Thanks class Button : public Widget; class SuperButton : public Button, public ModifiedWidget; I'm just not sure if that would do what I want it to though.

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  • Is it possible to override a property and return a derived type in VB.NET?

    - by Casey
    Consider the following classes representing an Ordering system: Public Class OrderBase Public MustOverride Property OrderItem() as OrderItemBase End Class Public Class OrderItemBase End Class Now, suppose we want to extend these classes to a more specific set of order classes, keeping the aggregate nature of OrderBase: Public Class WebOrder Inherits OrderBase Public Overrides Property OrderItem() as WebOrderItem End Property End Class Public Class WebOrderItem Inherits OrderItemBase End Class The Overriden property in the WebOrder class will cause an error stating that the return type is different from that defined in OrderBase... however, the return type is a subclass of the type defined in OrderBase. Why won't VB allow this?

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  • How do you make a private member in the base class become a public member in the base class?

    - by jasonline
    Consider the following code: class Base { void f() { } }; class Derived: public Base { public: }; What can you change in the derived class, such that you can perform the following: Derived d; d.f(); If the member is declared as public in the base class, adding a using declaration for Base::f in the derived class public section would've fix the problem. But if it is declared as private in the base class, this doesn't seem to work.

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  • Having troubles inheriting base class

    - by Nick
    When I inherit the base class, it's telling me there is no such class This is enhanced.h: class enhanced: public changeDispenser // <--------where error is occuring { public: void changeStatus(); // Function: Lets the user know how much of each coin is in the machine enhanced(int); // Constructor // Sets the Dollar amount to what the User wants void changeLoad(int); // Function: Loads what change the user requests into the Coin Machine int dispenseChange(int); // Function: Takes the users amount of cents requests and dispenses it to the user private: int dollar; }; This is enhanced.cpp: #include "enhanced.h" #include <iostream> using namespace std; enhanced::enhanced(int dol) { dollar = dol; } void enhanced::changeStatus() { cout << dollar << " dollars, "; changeDispenser::changeStatus(); } void enhanced::changeLoad(int d) { dollar = dollar + d; //changeDispenser::changeLoad; } This is changeDispenser.h: class changeDispenser { public: void changeStatus(); // Function: Lets the user know how much of each coin is in the machine changeDispenser(int, int, int, int); // Constructor // Sets the Quarters, Dimes, Nickels, and Pennies to what the User wants void changeLoad(int, int, int, int); // Function: Loads what change the user requests into the Coin Machine int dispenseChange(int); // Function: Takes the users amount of cents requests and dispenses it to the user private: int quarter; int dime; int nickel; int penny; }; I didn't include the driver file or the changeDispenser imp file, but in the driver, these are included #include "changeDispenser.h" #include "enhanced.h"

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  • Want to mimic iphone address book search (In terms of interface & interaction)

    - by mr-sk
    Hi, When you do a search in the address book the flow is: 1) Select the search bar 2) The right most transparent a-z index is removed 3) A transparent black window is placed over the current UITableView 4) When you begin typing, a new UITableView is loaded with no data 5) The UITableView is populated with data as you type. 6) If you select an item you are brought to it 7) If you cancel the search you return to the main UITalbeView My first real question is, how do I load a new UITableView when a user begins searching? Is it as easy as popping a new view on the stack? It would then be a seperate .m/.h file with its own implementation? The second question is how do you remove the right most index? Or just that just go away when you render the new (blank) UITableView? I've gotten search working, but mine does it in the same UITableView, which when you start contains like 2K results, is grouped (A results under A Heading, etc) and has a right most index. I'd be happy leaving the results in the table, if I could; 1) Remove the rightmost a-z index 2) Drop the table groupings 3) Tell the view I only have N search results so it will build the scroll bar correctly. Thanks for your input; sk

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