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  • Adding STI to Existing Table...

    - by keruilin
    I want to add STI to an existing table using a custom type column. Let's call this taste_type whose corresponding model is Fruit. In the Fruit model I have: set_inheritance_column :taste_type In my migration to add STI I have: class AddSTI < ActiveRecord::Migration def self.up add_column :fruits, :taste_type, :string, :limit => 100, :null => false Fruit.reset_column_information Fruit.find_by_id(1).update_attributes({:taste_type => 'Sour'}) end def self.down remove_column :fruits, :taste_type end end When I run the migration, I get the following error: Mysql::Error: Column 'taste_type' cannot be null: ... Any idea what's going? I can get the migration to run if I comment the set_inheritance_column in the Fruit model, then uncomment it after I run the migration. Obviously, I don't want to do this, however.

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  • Man machine interface command syntax and parsing

    - by idimba
    What I want is to add possibility to interact with application, and be able to extract information from application or event ask it to change some states. For that purpose I though of building cli utility. The utility will connect to the application and send user commands (one line strings) to the application and wait for response from the application. The command should contain: - command name (e.g. display-session-table/set-log-level etc.) - optionally command may have several arguments (e.g. log-level=10) The question to choose syntax and to learn parse it fast and correctly. I don't want to reinvent the whell, so maybe there's already an answer out there.

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  • Trying to recognize _NSFaultingMutableSet as member of NSSet

    - by Will
    I'm trying to recognize the result of a generic query to a managed object as an NSSet. Currently the class returned is a member of _NSFaultingMutableSet, which is clearly related, but fails the isMemberOf:[NSSet class] and isKindOf:[NSSet class] calls. Given that Cocoa doesn't do a direct implementation of NSSet, it's not surprising that I've got some air in the pipes, but I'm wondering if I'm messing something obvious up or this requires a higher grade of kung-fu than I possess. Code follows: SEL selector = NSSelectorFromString(someString); if(![self respondsToSelector:selector]){ NSLog(@"Error processing item"); return; } id items = [self performSelector:selector]; Class itemsClass = [items class]; if ( [itemsClass isKindOfClass:[NSSet class]]) { // do something }

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  • Conversion of pointer-to-pointer between derived and base classes?

    - by Mike Mueller
    Regarding the following C++ program: class Base { }; class Child : public Base { }; int main() { // Normal: using child as base is allowed Child *c = new Child(); Base *b = c; // Double pointers: apparently can't use Child** as Base** Child **cc = &c; Base **bb = cc; return 0; } GCC produces the following error on the last assignment statement: error: invalid conversion from ‘Child**’ to ‘Base**’ My question is in two parts: Why is there no implicit conversion from Child** to Base**? I can make this example work with a C-style cast or a reinterpret_cast. Using these casts means throwing away all type safety. Is there anything I can add to the class definitions to make these pointers cast implicitly, or at least phrase the conversion in a way that allows me to use static_cast instead?

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  • Me As Child Type

    - by Steven
    I have a MustInherit Parent class with two Child classes which Inherit from the Parent. How can I use (or Cast) Me in a Parent function as the the child type of that instance? EDIT: My actual goal is to be able to serialize (BinaryFormatter.Serialize(Stream, Object)) either of my child classes. However, "repeating the code" in each child "seems" wrong.

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  • C# visually subclass datagridview control VS2005

    - by DRapp
    Maybe its something stupid, but I'm having a problem with a subclass of a DataGridView Control in VS2005 C#. I know I can subclass from almost anything by doing public class MyDataGridView : DataGridView {} no problem, and I put in some things / elements I want applicable globally. Now, I take this gridview and put into a custom user control that will contain other controls too. So I have something like created by the visual designer. I grab some buttons, label, and my derived "MyDataGridView" on it. public partial class MyCompoundDGVPlus : UserControl So, now, I can visually draw, move, change all sorts of settings as needed, no problem. Now, I want this "MyCompoundDGVPlus" class as the basis for other classes, of which I will manipulate settings specific, but want all to have the same look / feel, and otherwise similar flow, hence the derivations. I've even set the "modifiers" setting to public, so I SHOULD be able to modify any of the properties of the controls at any derived level. So, now, I create a new subclass of "MyFirstDetailedDGVPlus" derived from "MyCompoundDGVPlus". Ok visually, all the label, button, datagridview appear. However, now I want to specifically define the columns of the datagridview here in this class visually, but its locked. However, the LABEL on the form, I CAN get all the property settings.... What am I missing.

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  • ruby restrict attr_accessor in subclass

    - by Arivarasan
    I want restrict the access of superclass's method in subclass class Parent attr_accessor :first_name, :last_name def initialize(first_name, last_name) @first_name, @last_name = first_name, last_name end def full_name @first_name + " " + @last_name end end class Son < Parent attr_accessor :first_name def initialize(parent, first_name) @first_name = first_name @last_name = parent.last_name end def full_name @first_name + " " + @last_name end end p = Parent.new("Bharat", "Chipli") puts p.full_name s = Son.new(p, "Harry") s.last_name= "Smith" puts s.full_name here i am getting son's full name as "Harry Smith", but i want "Harry Chipli"

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  • Cocoa: Creating a Window with a Variable Number of Interface Elements

    - by Rui Pacheco
    Hi, I've a window that will have an unknown amount of text fields, determined by the content of a remote server. In high level terms, how should I go about this? Create a custom view or create an empty window with a backing NSWindowController and then add stuff to it when the window is opened? I've seen the examples on the O'Reilly Cocoa book and those effectively create a custom NSView. Is this the right way to do it, 8 year later?

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  • User Interface functionality modelling languages?

    - by naugtur
    I am looking for a UI functionality modelling language (UML-alike "thing", but for user interfaces) that is already accepted and maybe has its design patterns and handles the problem better than state or activity diagram. (If there is no such thing I'm planning to develop that BTW :)) This question came to mind as a result of a discovery that UML and its diagrams fails at describing complicated UI functionality with event-driven flow of execution (ie. javascript/jQuery big projects) EDIT: I've been thinking of using BPMN but It was not created for this purpose. EDIT2: See this community topic of mine - I decided to start developing said language.

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  • Working examples of winform/WPF apps

    - by melody
    I'm a user interface designer. The project I'm working on is a dashboard that will have several interactive and customizable widgets (think Netvibes, etc.). The development group is going to be using either WinForm or WPF to build the dashboard and widgets. I need to understand the capabilities of each technology better and see a sampling of actual working apps to help accomplish this. I can't download and build examples... need live examples somewhere on the web. Can you point me to live, existing apps? Thx.

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  • Flash External Interface issue with Firefox

    - by majestiq
    I am having a hard time getting ExternalInterface to work on Firefox. I am trying to call a AS3 function from javascript. The SWF is setup with the right callbacks and it is working in IE. I am using AC_RunActiveContent.js to embed the swf into my page. However, I have modified it to add an ID to the Object / Embed Tags. Below are object and embed tag that are generated for IE and for Firefox respectively. <object codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=9,0,0,0" width="400" height="400" align="middle" id="jpeg_encoder2" name="jpeg_encoder3" classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" > <param name="movie" value="/jpeg_encoder/jpeg_encoder3.swf" /> <param name="quality" value="high" /> <param name="play" value="true" /> <param name="loop" value="true" /> <param name="scale" value="showall" /> <param name="wmode" value="window" /> <param name="devicefont" value="false" /> <param name="bgcolor" value="#ffffff" /> <param name="menu" value="false" /> <param name="allowFullScreen" value="false" /> <param name="allowScriptAccess" value="always" /> </object> <embed width="400" height="400" src="/jpeg_encoder/jpeg_encoder3.swf" quality="high" pluginspage="http://www.macromedia.com/go/getflashplayer" align="middle" play="true" loop="true" scale="showall" wmode="window" devicefont="false" id="jpeg_encoder2" bgcolor="#ffffff" name="jpeg_encoder3" menu="false" allowFullScreen="false" allowScriptAccess="always" type="application/x-shockwave-flash" > </embed> I am calling the function like this... <script> try { document.getElementById('jpeg_encoder2').processImage(z); } catch (e) { alert(e.message); } </script> In Firefox, I get an error saying "document.getElementById("jpeg_encoder2").processImage is not a function" Any Ideas?

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  • Final classes in Python 3.x- something Guido isn't telling me?

    - by GlenCrawford
    This question is built on top of many assumptions. If one assumption is wrong, then the whole thing falls over. I'm still relatively new to Python and have just entered the curious/exploratory phase. It is my understanding that Python does not support the creating of classes that cannot be subclassed (final classes). However, it seems to me that the bool class in Python cannot be subclassed. This makes sense when the intent of the bool class is considered (because bool is only supposed to have two values: true and false), and I'm happy with that. What I want to know is how this class was marked as final. So my question is: how exactly did Guido manage to prevent subclassing of bool? >>> class TestClass(bool): pass Traceback (most recent call last): File "<pyshell#2>", line 1, in <module> class TestClass(bool): TypeError: type 'bool' is not an acceptable base type Related question: http://stackoverflow.com/questions/2172189/why-i-cant-extend-bool-in-python

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  • Sharing view logic in Django

    - by Jeremy B.
    I've begun diving into Django again and I'm having trouble finding the parallel to some common concepts from my life in C#. While using .NET MVC I very often find myself creating a base controller which will provide a base action implementation to take care of the type of stuff I want to do on every request, like retrieving user information, getting localization values. Where I'm finding myself confused is how to do this in Django. I am getting more familiar with the MVT concept but I can't seem to find how to solve this scenario. I've looked at class based views and the generic views yet they didn't seem to work how I expected. What am I missing? How can i create default logic that each view will be instructed to run but not have to write it in each view method?

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  • Linq 2 SQL Store inherited classes - not mapped to tables in the database

    - by user348672
    Hi. I'm trying to introduce the Linq2SQL technique into the project and have encountered the following issue: I've created ORM classes based on the Northwind database. In some other application I create several classes derived from the Linq2SQL classes. I'm able to add such a class to EntitySet but the application fails to submit changes. Is there any way around this? Sample code(MyClass is derived from the Order): DataClasses1DataContext northwind = new DataClasses1DataContext(); Product chai = northwind.Products.Single(p => p.ProductName == "Chai"); Product tofu = northwind.Products.Single(p => p.ProductName == "Tofu"); Order myOrder = new Order(); myOrder.OrderDate = DateTime.Now; myOrder.RequiredDate = DateTime.Now.AddDays(1); myOrder.Freight = 34; Order_Detail myItem1 = new Order_Detail(); myItem1.Product = chai; myItem1.Quantity = 12345; Order_Detail myItem2 = new Order_Detail(); myItem2.Product = tofu; myItem2.Quantity = 3; myOrder.Order_Details.Add(myItem1); myOrder.Order_Details.Add(myItem2); Customer myCustomer = northwind.Customers.Single(c => c.CompanyName == "B's Beverages"); MyClass newOrder = new MyClass(); newOrder.OrderDate = DateTime.Now; newOrder.RequiredDate = DateTime.Now.AddDays(31); newOrder.Freight = 35; Order_Detail myItem3 = new Order_Detail(); myItem3.Product = tofu; myItem3.Quantity = 3; newOrder.Order_Details.Add(myItem3); myCustomer.Orders.Add(myOrder); myCustomer.Orders.Add(newOrder); As I said I'm able to add the newOrder object but unable to submit into the database.

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  • How to make a 3D UI for an application ?

    - by wacky_coder
    I'm building an application and I'd like its User Interface to be 3D, most probably a cylinder. The user would see the cylinder[Horizontally laid] and the cylinder's curved surface would have the buttons and any other controls that need to be placed. The cylinder needs to rotate and later, I'd like to add some other effects to the cylinder too. Someone told me that such a UI can be modelled using Maya or Blender and exported to openGL and then I could use C/C++ (with Qt) to carry out the actions. How can this be done?? Is there any other way to build the UI and do all the other things that I need ?? I really need some help because I have the UI in mind, but no idea on how to implement it. Thanks

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  • How can you extend the Bitmap class

    - by vrish88
    Hello, I am trying to extend the Bitmap class so that I can apply my own effects to an image. When I use this code: namespace ImageEditor { public class Effects : System.Drawing.Bitmap { public void toBlackAndWhite() { System.Drawing.Bitmap image = (Bitmap)this; AForge.Imaging.Filters.Grayscale filter = new AForge.Imaging.Filters.Grayscale(); this = filter.Apply(this); } } } I get the following error: 'ImageEditor.Effects': cannot derive from sealed type 'System.Drawing.Bitmap' So is there a way to get around this or is it simply not possible to extend the class? Thanks.

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  • Virgin STI Help

    - by Mutuelinvestor
    I am working on a horse racing application and I'm trying to utilize STI to model a horse's connections. A horse's connections is comprised of his owner, trainer and jockey. Over time, connections can change for a variety of reasons: The horse is sold to another owner The owner switches trainers or jockey The horse is claimed by a new owner As it stands now, I have model this with the following tables: horses connections (join table) stakeholders (stakeholder has three sub classes: jockey, trainer & owner) Here are my clases and associations: class Horse < ActiveRecord::Base has_one :connection has_one :owner_stakeholder, :through => :connection has_one :jockey_stakeholder, :through => :connection has_one :trainer_stakeholder, :through => :connection end class Connection < ActiveRecord::Base belongs_to :horse belongs_to :owner_stakeholder belongs_to :jockey_stakeholder belongs_to :trainer_stakeholder end class Stakeholder < ActiveRecord::Base has_many :connections has_many :horses, :through => :connections end class Owner < Stakeholder # Owner specific code goes here. end class Jockey < Stakeholder # Jockey specific code goes here. end class Trainer < Stakeholder # Trainer specific code goes here. end One the database end, I have inserted a Type column in the connections table. Have I modeled this correctly. Is there a better/more elegant approach. Thanks in advance for you feedback. Jim

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  • Can can I reference extended methods/params without having to cast from the base class object return

    - by Greg
    Hi, Is there away to not have a "cast" the top.First().Value() return to "Node", but rather have it automatically assume this (as opposed to NodeBase), so I then see extended attributes for the class I define in Node? That is is there a way to say: top.Nodes.First().Value.Path; as opposed to now having to go: ((Node)top.Nodes.First().Value).Path) thanks [TestMethod()] public void CreateNoteTest() { var top = new Topology(); Node node = top.CreateNode("a"); node.Path = "testpath"; Assert.AreEqual("testpath", ((Node)top.Nodes.First().Value).Path); // *** HERE *** } class Topology : TopologyBase<string, Node, Relationship> { } class Node : NodeBase<string> { public string Path { get; set; } } public class NodeBase<T> { public T Key { get; set; } public NodeBase() { } public NodeBase(T key) { Key = key; } } public class TopologyBase<TKey, TNode, TRelationship> where TNode : NodeBase<TKey>, new() where TRelationship : RelationshipBase<TKey>, new() { // Properties public Dictionary<TKey, NodeBase<TKey>> Nodes { get; private set; } public List<RelationshipBase<TKey>> Relationships { get; private set; } }

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  • How do I prevent JAXB from binding superclass methods of the @XmlRootElement when marshalling?

    - by Matt Fisher
    I have a class that is annotated as the @XmlRootElement with @XmlAccessorType(XmlAccessType.NONE). The problem that I am having is that the superclass's methods are being bound, when I do not want them to be bound, and cannot update the class. I am hoping there is an annotation that I can put on the root element class to prevent this from happening. Example: @XmlRootElement @XmlAccessorType(XmlAccessType.NONE) public class Person extends NamedObject { @XmlElement public String getId() { ... } } I would expect that only the methods annotated @XmlElement on Person would be bound and marshalled, but the superclass's methods are all being bound, as well. The resulting XML then has too much information. How do I prevent the superclass's methods from being bound without having to annotate the superclass, itself?

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  • Programming interface

    - by user309010
    Hi All, I currently building a data collection system [mainly "EFM" - enterprise feed back management] using .NET. I was wondering if there is a possibility to provide the user to script and manipulate the objects - like a programming language but with minor functionalities Thanks

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  • Why do pure virtual base classes get direct access to static data members while derived instances do

    - by Shamster
    I've created a simple pair of classes. One is pure virtual with a static data member, and the other is derived from the base, as follows: #include <iostream> template <class T> class Base { public: Base (const T _member) { member = _member; } static T member; virtual void Print () const = 0; }; template <class T> T Base<T>::member; template <class T> void Base<T>::Print () const { std::cout << "Base: " << member << std::endl; } template <class T> class Derived : public Base<T> { public: Derived (const T _member) : Base<T>(_member) { } virtual void Print () const { std::cout << "Derived: " << this->member << std::endl; } }; I've found from this relationship that when I need access to the static data member in the base class, I can call it with direct access as if it were a regular, non-static class member. i.e. - the Base::Print() method does not require a this- modifier. However, the derived class does require the this-member indirect access syntax. I don't understand why this is. Both class methods are accessing the same static data, so why does the derived class need further specification? A simple call to test it is: int main () { Derived<double> dd (7.0); dd.Print(); return 0; } which prints the expected "Derived: 7"

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