Search Results

Search found 46896 results on 1876 pages for 'temporary class'.

Page 447/1876 | < Previous Page | 443 444 445 446 447 448 449 450 451 452 453 454  | Next Page >

  • [Ruby On Rails] belongs_to with :class_name option fails.

    - by crackpot
    I have no idea what went wrong but I can't get belongs_to work with :class_name option. Could somebody enlighten me. Thanks a lot! Here is a snip from my code. class CreateUsers < ActiveRecord::Migration def self.up create_table :users do |t| t.text :name end end def self.down drop_table :users end end ##################################################### class CreateBooks < ActiveRecord::Migration def self.up create_table :books do |t| t.text :title t.integer :author_id, :null => false end end def self.down drop_table :books end end ##################################################### class User < ActiveRecord::Base has_many: books end ##################################################### class Book < ActiveRecord::Base belongs_to :author, :class_name => 'User', :validate => true end ##################################################### class BooksController < ApplicationController def create user = User.new({:name => 'John Woo'}) user.save @failed_book = Book.new({:title => 'Failed!', :author => @user}) @failed_book.save # missing author_id @success_book = Book.new({:title => 'Nice day', :author_id => @user.id}) @success_book.save # no error! end end environment: ruby 1.9.1-p387 Rails 2.3.5

    Read the article

  • Communicating between classes

    - by zachary
    I have a form that is divided into two classes. Each class represents the widgets on part of the form. What is the best way to allow these classes to share data between each other and update each other. Example: Button in class A is clicked. Update text field in class C

    Read the article

  • doubt in - Function Objects - c++

    - by Eternal Learner
    I have a class class fobj{ public: fobj(int i):id(i) {} void operator()() { std::cout<<"Prints"<<std::endl; } private: int id; }; template<typename T> void func(T type) { type(); } My Doubt is if I invoke func like Method 1: func(fobj(1); the message I wanted to print is printed. I was always thinking I needed to do something like Method 2: fobj Iobj(1); // create an instance of the fobj class func(Iobj); //call func by passing Iobj(which is a function object) How does Method 1 work? I mean what exactly happens? and how is a call made to the operator() in class fobj ?

    Read the article

  • c++ template and its element type

    - by David
    This is my template matrix class: template<typename T> class Matrix { public: .... Matrix<T> operator / (const T &num); } However, in my Pixel class, I didn't define the Pixel/Pixel operator at all! Why in this case, the compiler still compiles?

    Read the article

  • what is the reason i am getting out put is 111?

    - by kam
    Hi, #include "stdafx.h" #include<iostream.h> template<class T> class Sample { public: Sample(); static int i; }; template<class T> int Sample<T>::i = 0; template<class T> Sample<T>::Sample() { i++; cout<<i; } void main() { Sample<int>s1; Sample<float>s2; Sample<char>s3; } output: 111 what is the reason i am getting out put is 111?

    Read the article

  • final fields and thread-safety

    - by pcjuzer
    Should it be all fields, including super-fields, of a purposively immutable java class 'final' in order to be thread-safe or is it enough to have no modifier methods? Suppose I have a POJO with non-final fields where all fields are type of some immutable class. This POJO has getters-setters, and a constructor wich sets some initial value. If I extend this POJO with knocking out modifier methods, thus making it immutable, will extension class be thread-safe?

    Read the article

  • Java: Superclass to construct a subclass on certain conditions, possible?

    - by ramihope
    I have this condition public class A { public action() { System.out.println("Action done in A"); } } public class B extends A { public action() { System.out.println("Action done in B"); } } when I create an instance of B, the action will do just actions in B, as it overrides the action of the superclass. the problem is that in my project, the super class A is already used too many times, and I am looking for a way that under certain conditions, when i create an instance of A it makes a check and if it is true, replace itself with B. public class A { public A() { if ([condition]) { this = new B(); } } public action() { System.out.println("Action done in A"); } } A a = new A(); a.action(); // expect to see "Action done in B"... is this possible in some way?

    Read the article

  • Static variable definition order in c++

    - by rafeeq
    Hi i have a class tools which has static variable std::vector m_tools. Can i insert the values into the static variable from Global scope of other classes defined in other files. Example: tools.h File class Tools { public: static std::vector<std::vector> m_tools; void print() { for(int i=0 i< m_tools.size() ; i++) std::cout<<"Tools initialized :"<< m_tools[i]; } } tools.cpp File std::vector<std::vector> Tools::m_tools; //Definition Using register class constructor for inserting the new string into static variable. class Register { public: Register(std::string str) { Tools::m_tools.pushback(str); } }; Different class which inserts the string to static variable in static variable first_tool.cpp //Global scope declare global register variable Register a("first_tool"); //////// second_tool.cpp //Global scope declare global register variable Register a("second_tool"); Main.cpp void main() { Tools abc; abc.print(); } Will this work? In the above example on only one string is getting inserted in to the static list. Problem look like "in Global scope it tries to insert the element before the definition is done" Please let me know is there any way to set the static definiton priority? Or is there any alternative way of doing the same.

    Read the article

  • Constructor initialising an array of subobjects?

    - by ojw
    Say I have several objects within a class, each of which needs constructing with a different value. I can write something like this: class b { public: b(int num) { // 1 for a.b1, and 2 for a.b2 } }; class a { public: b b1; b b2; a() : b1(1), b2(2) { } }; However, is it possible to do the same thing if those multiple objects are stored in an array? My first attempt at it doesn't compile: class a { public: b bb[2]; a() : bb[0](1), bb[1](2) { } };

    Read the article

  • Android HTTP get methods

    - by Nick
    I have written a number of applications for blackberry and am just starting in Android. It seems to me that android has a lot more built in functions. I am starting by recreating some of my BB apps on Android and on one I take a few xml sites and parse them out. On blackberry I implemented this by creating a class that extended a thread. I would construct a new instance of this class with the parameters of my http request and it would call a function back in my main class, sending it the results. I am tempted to reuse my code, but am curious if android has something better built in. I have been looking at the handler class as well as possible using a service. Bascially, I would like to start a new thread that will return a document of a specific url. Thanks!

    Read the article

  • Asp.net static object behaviour

    - by Circadian
    I have the following class as part of an asp.net application. public sealed class SomeClass { private static string appId = Guid.NewGuid().ToString(); public static ReadSomethingFromDb(){} public static WriteSomethingToDb(){} } There are more than one application instances in the same application pool, and they all access the same database. I want the operations performed by the above class to be uniquely tied to the instance that performed it, hence the use of the appId. So adding a record to the database would for example contain a name, address and appId. This has been simplified for discussion purposes. Assuming that I have two instances running at mysite.a and mysite.b the above class would generate two different guids. My problem is that mysite.a sometimes produces more than one guid, which is unexpected. Thank you in advance

    Read the article

  • What to prefer in the following case?

    - by GK
    say suppose I have class as : public class Age { private int age; public int getAge() { return this.age; } } In my Main class I am calling the getAge() method many times. So I wanted to know is it advisable to call so many times or call once and assign it to some variable and use that variable. Which is best and why?

    Read the article

  • jQueryUI widget text plus icon

    - by cf_PhillipSenn
    I have: <div class="ui-widget"> <div class="ui-widget-header"> My Menu<span class="ui-icon ui-icon-circle-triangle-n"></span> </div> <ul class="ui-widget-content"> <li>Menu Item 1</li> <li>Menu Item 2</li> <li>Menu Item 3</li> </ul> </div> Right now, the ui-icon is appearing below "My Menu" Q: How can I get "My Menu" to appear on the same line as the UI widget?

    Read the article

  • Calling a constructor to reinitialize variables doesn't seem to work?

    - by Matt
    I wanted to run 1,000 iterations of a program, so set a counter for 1000 in main. I needed to reinitialize various variables after each iteration, and since the class constructor had all the initializations already written out - I decided to call that after each iteration, with the result of each iteration being stored in a variable in main. However, when I called the constructor, it had no effect...it took me a while to figure out - but it didn't reinitialize anything! I created a function exactly like the constructor - so the object would have its own version. When I called that, it reinitialized everything as I expected. int main() { Class MyClass() int counter = 0; while ( counter < 1000 ) { stuff happens } Class(); // This is how I tried to call the constructor initially. // After doing some reading here, I tried: // Class::Class(); // - but that didn't work either /* Later I used... MyClass.function_like_my_constructor; // this worked perfectly */ } ...Could someone try to explain why what I did was wrong, or didn't work, or was silly or what have you? I mean - mentally, I just figured - crap, I can call this constructor and have all this stuff reinitialized. Are constructors (ideally) ONLY called when an object is created?

    Read the article

  • Three customer addresses in one table or in separate tables?

    - by DR
    In my application I have a Customer class and an Address class. The Customer class has three instances of the Address class: customerAddress, deliveryAddress, invoiceAddress. Whats the best way to reflect this structure in a database? The straightforward way would be a customer table and a separate address table. A more denormalized way would be just a customer table with columns for every address (Example for "street": customer_street, delivery_street, invoice_street) What are your experiences with that? Are there any advantages and disadvantages of these approaches?

    Read the article

  • Misunderstanding function pointer - passing it as an argument

    - by Stef
    I want to pass a member function of class A to class B via a function pointer as argument. Please advise whether this road is leading somewhere and help me fill the pothole. #include <iostream> using namespace std; class A{ public: int dosomeA(int x){ cout<< "doing some A to "<<x <<endl; return(0); } }; class B{ public: B(int (*ptr)(int)){ptr(0);}; }; int main() { A a; int (*APtr)(int)=&A::dosomeA; B b(APtr); return 0; } This brilliant piece of code leaves me with the compiler error: cannot convert int (A::*)(int)' toint (*)(int)' in initialization Firstly I want it to compile. Secondly I don't want dosomeA to be STATIC.

    Read the article

  • How do i get my search bar to actually work?

    - by Sam
    Hey guys, I've got a search bar and it looks fine, but i don't really know how to make it search the whole of my site... Here's my html code so far: <form class="search2" method="get" action="default.html" /> <input class="search2" type="text" name="serach_bar" size="31" maxlength="255" value="" style="left: 396px; top: 153px; width: 293px; height: 26px;" /> <input class="search1" type="submit" name="submition" value="Search" style=" padding- bottom:20px; left: 691px; top: 153px; height: 23px" /> <input class="search2" type="hidden" name="sitesearch" value="default.html" /> Thanks in advance guys!

    Read the article

  • how toaccess the attributes in another form? c#

    - by Chelsea_cole
    I have a problem in a same namespace: public partial class frmForm1 : Form // Form1 { public class Account { public string Username; public string Password; } public class ListAcc { public static int count = 0; private static List<Account> UserList; public static List<Account> Data() { return UserList; } } } public partial class frmForm2 : Form // Form2 { private void button2_Click(object sender, EventArgs e) { frmForm1.Account A; string m = frmForm1.ListAcc<A>.[0].Username; //ERROR } } How could i access the attributes (Username, Password...) in frmForm1? Someone help me? Thanks!

    Read the article

  • Boost singleton trouble

    - by Ockonal
    Hi guys, I have some class which uses boost singleton. It calls some function from own c++ library. This library is written in make file as dependence. Now I have another singleton class and it should call first singleton class. After this code I got linkers error about undefined references for functions which are used in first singleton. When I remove calling first singleton class from second the errors remove. Maybe there is something wrong?

    Read the article

  • null reference problems with c#

    - by alex
    Hi: In one of my window form, I created an instance of a class to do some works in the background. I wanted to capture the debug messages in that class and displayed in the textbox in the window form. Here is what I did: class A //window form class { public void startBackGroundTask() { B backGroundTask = new B(this); } public void updateTextBox(string data) { if (data != null) { if (this.Textbox.InvokeRequired) { appendUIDelegate updateDelegate = new appendUIDelegate(updateUI); try { this.Invoke(updateDelegate, data); } catch (Exception e) { Console.WriteLine(e.Message); } } else { updateUI(data); } } } private void updateUI(string data) { if (this.Textbox.InvokeRequired) { this.Textbox.Invoke(new appendUIDelegate(this.updateUI), data); } else { //update the text box this.Textbox.AppendText(data); this.Textbox.AppendText(Environment.NewLine); } } private delegate void appendUIDelegate(string data); } class B // background task { A curUI; public b( A UI) { curUI = UI; } private void test() { //do some works here then log the debug message to UI. curUI.updateTextBox("message); } } I keep getting a null reference exception after this.Invoke(updateDelegate, data); is called. I know passing "this" as a parameter is strange. But I want to send the debug message to my window form. Please help. Thanks

    Read the article

  • Unable to run JAR file (created in Eclipse)

    - by Trist
    I hate starting a post with this but I'm new to Java... I've followed this tutorial to create a socket server (mines in Eclipse). I can run the server within Eclipse, all is well. But when I try to export the project I can't figure out how to run it. I keep getting this error (it varies depending on how I run it) Exception in thread "main" java.lang.NoClassDefFoundError: xsocketserver/Main Caused by: java.lang.ClassNotFoundException: xsocketserver.Main at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:315) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:330) at java.lang.ClassLoader.loadClass(ClassLoader.java:250) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:398) I've read this problem relates to class paths being set. I've tried the following: java -cp libs/xSocket-2.8.12.jar xsocketserver.Main java -jar xSocketServer.jar java -classpath xSocketServer:xSocketServer/libs/xSocket-2.8.12.jar xsocketserver.Main plus many others. The file structure within the JAR is as follows: xSocketServer.jar -> xsocketserver -> Main.class -> xSocketDataHandler.class -> META-INF -> MANIFEST.MF -> libs -> xSocket-2.8.12.jar Incidentally I've tried adding my own manifest file which contains the Class-Path but when I check it it always reads: Manifest-Version: 1.0 Main-Class: xsocketserver.Main I'm guessing this is a common problem based on the number of hits I've seen in Google but I can't fathom what I'm doing wrong. Wrong Export settings maybe??

    Read the article

  • java.util.Observable, will clients complete executing their update() before continuing

    - by jax
    When I call: setChanged(); notifyObservers() on a java.until.Observable class, will all the listening Observer objects complete execution of their udpate() methods - assuming we are running in the same Thread - before the java.until.Observable class continues running? This is important because I will be sending a few messages through the notifyObservers(Object o) method in quick concession, it is important that each Observer class has finished its method before the new one though. I understand that the order of execution for each Observer class may vary when we call notifyObservers() - it is just important that the order of method execution for each individual instance is in order.

    Read the article

  • Calling child constructor by casting (ChildClass)parentObject; to track revisions

    - by FreshCode
    To track revisions of a Page class, I have a PageRevision class which inherits from Page and adds a revision ID (Guid RevisionID;). If possible, how should I cast an existing Page object to a PageRevision and ensure that the PageRevision constructor is called to create a new revision ID? I could could have a PageRevision(Page page) constructor which generates the Guid and copies all the Page attributes, but I want to automate it, especially if a Page class has many attributes (and I later add one, and forget to modify the copy constructor). Desired use Page page = new Page(123, "Page Title", "Page Body"); // where 123 is page ID PageRevision revision = (PageRevision)page; // now revision.RevisionID should be a new Guid. Page, PageRevision classes: public class Page { public int ID { get; set; } public string Title { get; set; } public string Body { get; set; } } public class PageRevision : Page { public Guid RevisionID { get; set; } public PageRevision() { this.RevisionID = Guid.NewGuid(); } }

    Read the article

  • jquery XML, i need .html() not .text() but not working?

    - by Xtian
    I need var long to be exported as html and not text. I know I have .text() but when I use .html() it will not work. Also if I take the .text() out when declaring the variable and it will not work in IE? The reason for this is, in the XML certain words will have html tags like or and I need those to be recognized. I thought I solved it when I took out .text() but then i looked at IE and I got nothing. $(document).ready(function(){ $.ajax({ type: "GET", url: "xml/sites.xml", dataType: "xml", success: function(xml) { $(xml).find('site').each(function(){ var id = $(this).attr('id'); var title = $(this).find('title').text(); var class =$(this).find('class').text(); $('<div class="'+class+'" id="link_'+id+'"></div>').html('<h2>'+title+'</h2>').appendTo('#page-wrap'); $(this).find('desc').each(function(){ var long = $(this).find('long'); var url = $(this).find('url').text(); $('<div class="long"></div>').html(long).appendTo('#link_'+id); $('<a href="http://'+url+'"</a>').html(url).appendTo('#link_'+id); }); }); } }); });// JavaScript Document

    Read the article

  • AJAX Closures and targeting 'this'

    - by Nick Lowman
    In the code example below the success callback function logs 'input#04.update' four times rather than each individual input, which makes sense seeing how closures work but how would I go about targeting each individual input using this. <input type="text" name="" id="01" class="update"> <input type="text" name="" id="02" class="update"> <input type="text" name="" id="03" class="update"> <input type="text" name="" id="04" class="update"> function updateFields(){ $('input.update').each(function(){ $this = $(this); $.ajax({ data: 'id=' + this.id, success: function(resp){ console.log($this); $this.val(resp) } }); }); }

    Read the article

< Previous Page | 443 444 445 446 447 448 449 450 451 452 453 454  | Next Page >