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  • Ruby Methods: return an usage string when insufficient arguments are given

    - by Shyam
    Hi, After creating a serious bunch of classes, with initialize methods, loading them in IRb requires to look back at the code. However, I think it should be easy enough to return a usage message, instead of: ArgumentError: wrong number of arguments (0 for 9) So I prefer to return a string with the human readable arguments, by example using "puts" or just a return of a string. Now I have seen the rescue keyword inside begin-end code, but I wonder how I could catch the ArgumentError when the initialize method is called. Thank you for your answers, feedback and comments!

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  • asp.net mvc model - my own database

    - by progtick
    The tutorials I have come across usually let you create a dababase from scratch creating a .mdf file or something and so on. However, what if I already have a SQL Server Express set up with the needed database? How do I tell my model to use that database? Right now, all my model contains is basically some classes that execute stored procedure on my own database and return manupulated data. Should I leave it as it is? What are the benefits of going through the full-fledged model approach that tutorials demonstrate?

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  • What is the best way to "override" enums?

    - by Tyler
    I have a number of classes which extend an abstract class. The abstract parent class defines an enum with a set of values. Some of the subclasses inherit the parent class's enum values, but some of the subclasses need the enum values to be different. Is there any way to somehow override the enum for these particular subclasses, and if not, what is a good way to achieve what I'm describing? class ParentClass { private MyEnum m_EnumVal; public virtual MyEnum EnumVal { get { return m_EnumVal; } set { m_EnumVal = value; } } public enum MyEnum { a, b, c }; } class ChildClass : ParentClass { private MyEnum m_EnumVal; public virtual MyEnum EnumVal { get { return m_EnumVal; } set { m_EnumVal = value; } } public enum MyEnum { d, e, f }; }

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  • Avoid stuck calling callback

    - by andlomba
    Hello all, This is a question about generic c++ event driven applications design. Lets assume that we have two threads, a "Dispatcher" (or "Engine"...) and a "Listener" (or "Client"...). Let's assume that I write the Dispatcher code, and release it as a library. I also write the Listener interface, of course. When the Dispatcher executes (after Listener registration) listenerInstance.onSomeEvent(); the event handling code will actually be executed by the Dispatcher thread, so if the person that implements the Listener writes something like void Listener::onSomeEvent() { while(true) ; } The Dispatcher will stuck forever. Is there a "plain old c++" (I mean no boost or libsigc++) way to "decouple" the two classes, so I can be sure that my Dispatcher will work fine whatever the Listeners does in the callbacks? bye and thanks in advance, Andrea

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  • what else to do to establish many-to-many associations in Ruby on Rails? thanks!

    - by john
    Hi, I have two classes and I want to establish a many-to-many assications, here is the code: class Category < ActiveRecord::Base has_and_belongs_to_many :events has_and_belongs_to_many :tips end class Tip < ActiveRecord::Base has_and_belongs_to_many :categories However, I kept getting the following errors and I would appreciate it if some one could educate me what is going wrong: PGError: ERROR: relation "categories_tips" does not exist : SELECT "categories".id FROM "categories" INNER JOIN "categories_tips" ON "categories".id = "categories_tips".category_id WHERE ("categories_tips".tip_id = NULL ) the viewer part: 4: <%= text_field :tip, :title %></label></p> 5: 6: <p><label>Categories<br/> 7: <%= select_tag('categories[]', options_for_select(Category.find(:all).collect {|c| [c.name, c.id] }, @tip.category_ids), :multiple => true ) %></label></p> 8: 9: <p><label>Location<br/> 10: <%= text_field_with_auto_complete :tip, :abstract %></label></p>

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  • PHP: Class extends problem "Call to private method ... from context ..."

    - by sombe
    I have 3 classes in WordPress (the question itself is unrelated to it): class WP_Widget class Theme_Widget extends WP_Widget class Specific_Widget extends Theme_Widget Essentially Theme_Widget contains some extension functions to the basic WP_Widget. Inside Specific_Widget I call one of Theme_Widget's methods: class Specific_Widget { function __construct() { $this->some_method_that_belongs_to_Theme_Widget(); } } When I instantiate Specific_Widget, PHP throws a fatal error as follows: Fatal error: Call to private method Theme_Widget::some_method_that_belongs_to_Theme_Widget() from context 'Specific_Widget' in ... Do you have an idea as to how I can resolve this? This is the first time I've received this error from PHP. Could it be derive from WordPress itself?

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  • What features of Scala cannot be translated to Java?

    - by Paul
    The Scala compiler compiles direct to Java byte code (or .NET CIL). Some of the features of Scala could be re-done in Java straightforwardly (e.g. simple for comprehensions, classes, translating anonymous/inner functionc etc). What are the features that cannot be translated that way? That is presumably mostly of academic interest. More usefully, perhaps, what are the key features or idioms of Scala that YOU use that cannot be easily represented in Java? Are there any the other way about? Things that can be done straightforwardly in Java that have no straightforward equivalent in Scala? Idioms in Java that don't translate?

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  • Cocoa Interface Builder object initialization

    - by Stanley
    Base on the documentation and sample code that I have gone through, I got an impression that when a class defined in xcode is read into and configured in Interface Builder, an object based on the class is effectively created and stored in an xib or nib file. So the object is ready to be used when the corresponding application is launched. Alternatively, for classes that have not been handled by Interface Builder, code such as the "new" statements have to be written in xcode explicitly in order for the associated objects to be created and used. It will be very nice to have people who are more knowledgable than me to confirm or to correct my very naive understanding of Interface Builder ...

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  • JPanel superclass doesn't add the components of its subclasses..

    - by Acryl
    Well, I use a JFrame that adds two JPanels. Those JPanels are superclasses, because I find it easier to separate different areas of the GUI into different classes. But here's the problem: I add the (superclass) JPanel to the JFrame I set the layout of the superclass JPanel to new BorderLayout(); I add components in the subclasses, like this: JPanel panel = new JPanel(); panel.setLayout(new GridLayout(2,1)); panel.add(new JLabel("Label:"); panel.add(new JTextField(); add(panel, BorderLayout.NORTH); But it doesn't show. What do I do wrong? I've tried it without an additional JPanel in the subclasses, but it doesn't work either. I use jdk 1.6

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  • XmlNode.InnerText

    - by Jonathan.Peppers
    We have XML like so: <Example> <Node>Some text here <ChildNode>Child 1</ChildNode> <ChildNode>Child 2</ChildNode> </Node> </Example> We are using XmlDocument to parse this. When we have the XmlNode of the Node element, XmlNode.InnerText returns us this: "Some text hereChild 1Child2" How can we get the inner text of the Node element without the child nodes' inner text? We don't really want to use any Regex or string splitting to accomplish this. Note: We also don't want to switch to using a different set of classes to parse this XML, it would be too much of a code change.

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  • stick element to top of page until next element of that type appears

    - by aharon
    I'm having a hard time giving a good description of this, but bear with me: If I have a page structed like this <h2>Chapter 1</h2> <p>Lots of text that has mutiple screen worths of content</p> <h2>Chapter 2</h2> <p>Lots of text...</p> I'd like to have "Chapter 1" absolutely positioned or whatever at the top of the page until the user scrolls down to where "Chapter 2" starts, at which point now "Chapter 2" is displayed at the top of the page. We can add wrapper classes and divs if needed. Solutions that use JQuery would be great.

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  • NULL In a Class Destructor

    - by Hyper-DarkStar
    Simple question; Is it pointless to set a pointer( which allocates heap memory ) to NULL in the destructor? class SampleClass { public: SampleClass( int Init = 0 ) { Value = new int( Init ); } ~SampleClass( void ) { delete Value; Value = NULL; // Is this pointless? } int *Value; }; While on the subject of classes, when should I use the explicit keyword? Thanks.

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  • how to call a function to refresh GUI

    - by SWKK
    Hi Guys, I am refactoring some code to decouple GUI from some state. #include <StateObject> Class GUI{ ... StateObject A; void doSomething() { A->hullaballoo();} **void ReFreshMyGui() { //take state A and redraw }** }; State object is being shared by multiple classes to update the state but this Gui Object specializes in displaying the state. So I would like to call the Refresh function via StateObject whenever its modified. I am not sure how or if signals will provide the solution. Any hints?

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  • "Reloading" Bindings in Ninject2?

    - by Michael Stum
    I'm using Ninject2 for DI and I have a Module that loads data from a config file. I wonder if there is a way to tell the Kernel or the Module to reload the config? (I can trigger that through code if needed) What worries me is the lifetime of existing objects. Say I have ITest bound to TestImpl1 in Singleton Scope and I change the config to bind ITest to TestImpl2 instead. All new requests should get TestImpl2, but the classes that already requested TestImpl1 before obviously keep it. However, what if all users of TestImpl1 are gone - will TestImpl1 be properly garbage collected and disposed in case it implements IDisposable? Or will it just be orphaned? Do I have to loop through each type and call Unbind/Bind on it? Or can I just unload the entire Module and reload it while still managing any existing object?

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  • [MAC] Using a proxy for NSURLConnection

    - by SideSwipe
    Is there any way to get the content of a webfile (namely a .html Document) using a proxy, which is not defined in the system settings? I know that NSURLConnection is the right way to download a web file into a variable and not into a file (for which we should use NSURLDownload), but I don't find an way to use a proxy for it. Are there some inofficial APIs, Librarys or Classes or such I could use for what I want to do? I'm not that pro in Mac Programming, so im searching for something more or less simple to do for me plz. SideSwipe

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  • Unrecognized option: -o Could not create the Java virtual machine.

    - by Kerubu
    I've got an unusual build error when using Buildroot to create an image for my Phidget SBC. It's unusual because it occurs ONLY on my development laptop and NOT on my general use laptop even though I am using EXACTLY the same Builroot environment as published by Phidgets themselves. When I try to create my Buildroot image I get the following error when it attempts to compile GNU classpath: Making all in tools make[2]: Entering directory `/home/xxxx/buildroot_phidgetsbc/buildroot-phidgetsbc_1.0.4.20111028/output/build/classpath-0.98/tools' /bin/mkdir -p classes asm /bin/mkdir -p ../tools/generated/gnu/classpath/tools/gjdoc/expr java -classpath antlr.Tool -o ../tools/generated/gnu/classpath/tools/gjdoc/expr/ \ ./gnu/classpath/tools/gjdoc/expr/java-expression.g Unrecognized option: -o Could not create the Java virtual machine. make[2]: *** [tools.zip] Error 1 The only difference I can possibly thing of is the different Linux (Ubuntu) versions I am using on each laptop. Also I cannot find a -o option documented for Java and don't understand why it works on one laptop but not the other. Any suggestions would be helpful.

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  • execute external command / application from java

    - by IttayD
    I'm looking for a package to support reliably executing external processes from Java. My criteria: Abstract over OS. So if I want to run 'foo', it will look for 'foo.bat', 'foo.exe' under windows and 'foo' under other OSs (or, have a way of passing a map of os-command) Being able to execute Java classes by simply giving the class name and arguments (so the package locates the java command, copies jvm flags and then executes) Process stdout and stderr properly Watchdog / Monitoring capabilities I've looked at commons-exec but it looks like it answers only 3 & 4. Ant has support for execution but looks like an overkill to use it for this purpose only.

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  • c# .net framework subtracting time-span from date

    - by smkngspcmn
    I want to subtract a time-span from a date-time object. Date is 1983/5/1 13:0:0 (y/m/d-h:m:s) Time span is 2/4/28-2:51:0 (y/m/d-h:m:s) I can use the native DateTime and TimeSpan objects to do this, after converting years and months of the time-span to days (assuming a 30 day month and a ~364 day year). new DateTime(1981,5,1,13,0,0).Subtract(new TimeSpan(878,13,51,0)); With this i get the result: {12/4/1978 11:09:00 PM} But this is not exactly what i expected. If i do this manually (assuming a 30 day month) i get 1981/0/3-10:9:0 This is pretty close to what i'm after except i shouldn't get 0 for month and year should be 1980. So can someone please show me how i can do this manually and avoid getting a 0 month value? Also why do i get a completely different value when i use native classes?

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  • Difference between var and Class class in object creation

    - by Divine
    Its a silly question, however shocked to see different behaviors. Learning a lot. Lets say I have two classes below Class A { public void Display() { } } Class B : A { public void Display() { } } Class C : B { public void Display() { } } Class Final { static void Main() { var c = new C(); // B c = new C(); //My doubt is, both of the above gives different results. May I know B c = new C() creates object of B or C? What I understood is, it creates object of B. Then why we say "new C()"? I agree with C c = new C(); But I thought, B b = new C(); creates object of B. Where we use this style? Only when utilizing runtime polymorphism? (Overriding methods)? } }

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  • Using variables within Attributes in C#

    - by tehp
    We have some Well-Attributed DB code, like so: [Display(Name = "Phone Number")] public string Phone { get; set; } Since it is quite generic we'd like to use it again, but with a different string in the Name part of the attribute. Since it's an attribute it seems to want things to be const, so we tried: const string AddressType = "Student "; [Display(Name = AddressType + "Phone Number")] public string Phone { get; set; } This seems to work alright, except that having a const string means we can't overwrite it in any base classes, thereby removing the functionality that we originally were intending to add, and exposing my question: Is there a way to use some sort of variable inside of an attribute so that we can inherit and keep the attribute decorations?

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  • C# private (hidden) base class

    - by Loadmaster
    It is possible to make a C# base class accessible only within the library assembly it's compiled into, while making other subclasses that inherit from it public? For example: using System.IO; class BaseOutput: Stream // Hidden base class { protected BaseOutput(Stream o) { ... } ...lots of common methods... } public class MyOutput: BaseOutput // Public subclass { public BaseOutput(Stream o): base(o) { ... } public override int Write(int b) { ... } } Here I'd like the BaseOutput class to be inaccessible to clients of my library, but allow the subclass MyOutput to be completely public. I know that C# does not allow base classes to have more restrictive access than subclasses, but is there some other legal way of achieving the same effect?

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  • solutions for rapid front-end development?

    - by fayer
    im using mvc framework and i have learned some techniques that help me with different parts of RAD. models: doctrine/visual paradigm controllers/libraries: various design patterns now i only need to know what technique/solution i should use for the views so that i can create views more rapidly. cause i don't think it's efficient to code css/html manually, even though i understand it. its the same principle when using visual paradigm to create both my mysql database tables and doctrine model classes. i believe in using right tools will boost up development speed. so what could i use for the views to save time and energy and don't reinvent the wheel all the time? dreamweaver? any css generation tools? 960/blueprint for layout? suggestions? thanks

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  • Inheritance and Implicit Type Casting

    - by Josué Molina
    Suppose I have the following three classes: class Animal {}; class Human : public Animal {}; class Dog : public Animal { public: void setOwner(Animal* owner) { this->owner = owner; } private: Animal* owner; }; Why is the following allowed, and what exactly is happening? Dog d; Human h; d.setOwner(&h); // ? At first, I tried to cast it like this d.setOwner(&(Animal)h), but the compiler gave me a warning, and I hit a run-time error. Edit: the warning the compiler gave me was "taking address of temporary". Why is this so?

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  • Parse file to hash in Ruby

    - by Taschetto
    I'm a ruby newcomer who's trying to read a text file (a Valgrind simulation output) like this: -------------------------------------------------------------------------------- Profile data file 'temp/gt_1024_2_16.out' -------------------------------------------------------------------------------- I1 cache: 1024 B, 16 B, 2-way associative D1 cache: 32768 B, 64 B, 8-way associative LL cache: 3145728 B, 64 B, 12-way associative Profiled target: bash run.sh Events recorded: Ir I1mr ILmr Dr D1mr DLmr Dw D1mw DLmw Events shown: Ir I1mr ILmr Dr D1mr DLmr Dw D1mw DLmw Event sort order: Ir I1mr ILmr Dr D1mr DLmr Dw D1mw DLmw Thresholds: 99 0 0 0 0 0 0 0 0 Include dirs: User annotated: Auto-annotation: off -------------------------------------------------------------------------------- Ir I1mr ILmr Dr D1mr DLmr Dw D1mw DLmw -------------------------------------------------------------------------------- 1,894,017 246,981 2,448 519,124 4,691 2,792 337,817 1,846 1,672 PROGRAM TOTALS // other data I want to extract the PROGRAM TOTALS table and put it into a hash. Something like... myHash = { :Ir => 1894017, :I1mr => 246981, ILmr => 2448, ..., DLmw => 1672 } What are the best options for doing this? Could the CSV classes help me out? Thanks a bunch.

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  • ASP.NET MVC2 - usage of LINQ-generated class (validation problem)

    - by ile
    There are few things not clear to me about ASP.NET MV2. In database I have table Contacts with several fields, and there is an additional field XmlFields of which type is xml. In that field are stored additional description fields. There are 4 classes: Contact class which corresponds to Contact table and is defined by default when creating LINQ classes ContactListView class which inherits Contact class and has some additional properties ContactXmlView class that contains fields from XmlFields field ContactDetailsView class which merges ContactListView and ContactXmlView into one class and this one is used to display data in view pages ContactListView class has re-defined some properties from Contact class (so that I can add [Required] filter used for validation) - but I get warning message: 'ObjectTest.Models.Contacts.ContactListView.FirstName' hides inherited member 'SA.Model.Contact.FirstName'. Use the new keyword if hiding was intended. ContactDetailsView class is also used in a form when creating new contact and adding it to database. I am not sure if this is correct way, and the warning message confuses me a bit. Any advise about this? Thanks, Ile EDIT According to Jakob's instructions I tried it from scratch: [MetadataType(typeof(Person_Validation))] public partial class Person { } public class Person_Validation { [Required] string FirstName { get; set; } [Required] string LastName { get; set; } [Required] int Age { get; set; } } In Controller I have this: [HttpPost] public ActionResult Create(Person person, FormCollection collection) { if (ModelState.IsValid) { try { personRepository.Add(person); personRepository.Save(); } catch { return View(person); } } return RedirectToAction("Index"); } View: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Validate.Models.Person>" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Create </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <h2>Create</h2> <% using (Html.BeginForm()) {%> <%= Html.ValidationSummary(true) %> <fieldset> <legend>Fields</legend> <div class="editor-label"> <%= Html.LabelFor(model => model.FirstName) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.FirstName) %> <%= Html.ValidationMessageFor(model => model.FirstName) %> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.LastName) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.LastName) %> <%= Html.ValidationMessageFor(model => model.LastName) %> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.Age) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Age) %> <%= Html.ValidationMessageFor(model => model.Age) %> </div> <p> <input type="submit" value="Create" /> </p> </fieldset> <% } %> <div> <%= Html.ActionLink("Back to List", "Index") %> </div> </asp:Content> When posting new person with no values, nothing happens (page is just reloaded). When posting with some values, person is added to db. I have no idea what am I doing wrong.

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