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  • Linking/Combining Type Classes in Haskell

    - by thegravian
    Say I have two type classes defined as follows that are identical in function but different in names: class Monad m where (>>=) :: m a -> (a -> m b) -> m b return :: a -> m a class PhantomMonad p where pbind :: p a -> (a -> p b) -> p b preturn :: a -> p b Is there a way to tie these two classes together so something that is an instance of PhantomMonad will automatically be an instance of Monad, or will instances for each class have to be explicitly written? Any insight would be most appreciated, thanks!

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  • Creating a custom categories widget

    - by Scott B
    The code below is an attempt to take the WP_Widget_Categories class and use it as the basis for a custom categories widget based on the default categories widget. I'm getting no output however and the widget is not showing up in the "Available Widgets" listing. What am I doing wrong? <?php /* Plugin Name: My Categories Widget Version: 1.0 */ class MY_Widget_Categories extends WP_Widget { function MY_Widget_Categories() { $widget_ops = array( 'classname' => 'widget_categories', 'description' => __( "A list or dropdown of categories" ) ); $this->WP_Widget('categories', __('Categories'), $widget_ops); } function widget( $args, $instance ) { extract( $args ); $title = apply_filters('widget_title', empty( $instance['title'] ) ? __( 'Categories' ) : $instance['title']); $c = $instance['count'] ? '1' : '0'; $h = $instance['hierarchical'] ? '1' : '0'; $d = $instance['dropdown'] ? '1' : '0'; echo $before_widget; if ( $title ) echo $before_title . $title . $after_title; $cat_args = array('orderby' => 'name', 'show_count' => $c, 'hierarchical' => $h); if ( $d ) { $cat_args['show_option_none'] = __('Select Category'); wp_dropdown_categories(apply_filters('widget_categories_dropdown_args', $cat_args)); ?> <script type='text/javascript'> /* <![CDATA[ */ var dropdown = document.getElementById("cat"); function onCatChange() { if ( dropdown.options[dropdown.selectedIndex].value > 0 ) { location.href = "<?php echo get_option('home'); ?>/?cat="+dropdown.options[dropdown.selectedIndex].value; } } dropdown.onchange = onCatChange; /* ]]> */ </script> <?php } else { ?> <ul> <?php $cat_args['title_li'] = ''; wp_list_categories(apply_filters('widget_categories_args', $cat_args)); ?> </ul> <?php } echo $after_widget; } function update( $new_instance, $old_instance ) { $instance = $old_instance; $instance['title'] = strip_tags($new_instance['title']); $instance['count'] = $new_instance['count'] ? 1 : 0; $instance['hierarchical'] = $new_instance['hierarchical'] ? 1 : 0; $instance['dropdown'] = $new_instance['dropdown'] ? 1 : 0; return $instance; } function form( $instance ) { //Defaults $instance = wp_parse_args( (array) $instance, array( 'title' => '') ); $title = esc_attr( $instance['title'] ); $count = isset($instance['count']) ? (bool) $instance['count'] :false; $hierarchical = isset( $instance['hierarchical'] ) ? (bool) $instance['hierarchical'] : false; $dropdown = isset( $instance['dropdown'] ) ? (bool) $instance['dropdown'] : false; ?> <p><label for="<?php echo $this->get_field_id('title'); ?>"><?php _e( 'Title:' ); ?></label> <input class="widefat" id="<?php echo $this->get_field_id('title'); ?>" name="<?php echo $this->get_field_name('title'); ?>" type="text" value="<?php echo $title; ?>" /></p> <p><input type="checkbox" class="checkbox" id="<?php echo $this->get_field_id('dropdown'); ?>" name="<?php echo $this->get_field_name('dropdown'); ?>"<?php checked( $dropdown ); ?> /> <label for="<?php echo $this->get_field_id('dropdown'); ?>"><?php _e( 'Show as dropdown' ); ?></label><br /> <input type="checkbox" class="checkbox" id="<?php echo $this->get_field_id('count'); ?>" name="<?php echo $this->get_field_name('count'); ?>"<?php checked( $count ); ?> /> <label for="<?php echo $this->get_field_id('count'); ?>"><?php _e( 'Show post counts' ); ?></label><br /> <input type="checkbox" class="checkbox" id="<?php echo $this->get_field_id('hierarchical'); ?>" name="<?php echo $this->get_field_name('hierarchical'); ?>"<?php checked( $hierarchical ); ?> /> <label for="<?php echo $this->get_field_id('hierarchical'); ?>"><?php _e( 'Show hierarchy' ); ?></label></p> <?php } } function my_categories_init() { register_sidebar_widget(__('My Categories Widget'), 'MY_Widget_Categories'); } add_action("plugins_loaded", "my_categories_init"); ?>

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  • User HasOne ActiveToken, HasMany Tokens, how to setup in Rails?

    - by viatropos
    I have two simple models: class User < ActiveRecord::Base has_many :tokens # has_one doesn't work, because Token already stores # foreign id to user... # has_one :active_token, :class_name => "Token" # belongs_to doesn't work because Token belongs to # User already, and they both can't belong to each other # belongs_to :active_token, :class_name => "Token" end class Token < ActiveRecord::Base belongs_to :user end I want to say "User has_one :active_token, :class_name => 'Token'", but I can't because Token already belongs_to User. What I did instead was just manually add similar functionality to the user like so: class User < ActiveRecord::Base has_many :tokens attr_accessor :active_token after_create :save_active_token before_destroy :destroy_active_token # it belongs_to, but you can't have both belongs_to each other... def active_token return nil unless self.active_token_id @active_token ||= Token.find(self.active_token_id) end def active_token=(value) self.active_token_id = value.id @active_token = value end def save_active_token self.active_token.user = self self.active_token.save end def destroy_active_token self.active_token.destroy if self.active_token end end Is there a better way?

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  • jQueryUI widgets

    - by cf_PhillipSenn
    How do I work with widgets? Here's what I've got so far: <html> <head> <script src="http://www.google.com/jsapi"></script> <script type="text/javascript"> google.load("jquery", "1"); google.load("jqueryui", "1"); </script> </head> <body> <div class="ui-widget"> <div class="ui-widget-header"> header </div> <div class="ui-widget-content"> content </div> </div> </body> </html> I'm trying to make a nice little div with a shaded header.

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  • Objective C - Custom Getter with inheritance

    - by anhdat
    Recently I have worked with Core Data. When I want to set a default value for some fields, I came up with this problem: So I made a simple represent: We have 2 class Parent and Child, in which Child inherit from Parent. // Parent.h @interface Parent : NSObject @property (strong, nonatomic) NSString *lastName; // Child.h @interface Child : Parent In Parent class, I made a custom getter to set a default value when nothing is set: // Parent.h - (NSString *)lastName { if (_lastName) { return _lastName; } else { return @"Parent Default Name"; } } But I cannot make a custom default value for the field "name" which Child inherits from its Parent. // Child.h @implementation Child - (NSString *)lastname { if (super.lastName) { return super.lastName; } else { return @"Child Default Name"; } } Apparently, this method is never called. So my question here is: How can I set a custom getter for the field the Child class inherits from Parent without define an overriding property?

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  • Should we or should we not check in the classes folder in WEB-INF directory into SVN?

    - by Vatsala
    I use SVN, and am learning how to use it along with eclipse IDE. The first time I add classes to my package, there is no problem, the generated class files get into SVN smoothly. The moment I edit them, I get this message - "WEB-INF/classes" is obstructed. I try the "clean-up" command and the clean up command says "WEB-INF/classes" folder is locked. I use TortoiseSVN as my SVN client. I know why this is happening. It probably because the Eclipse overwrites all the files while generating classes and then causes this - Is it inappropriate to commit the class files into SVN? If not, what should I do to commit these class files smoothly?

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  • How to create a project from existing source in Eclipse and then find it?

    - by Roman
    I have created several .class files. All of them are located in one directory. I used a text editor to write these class files. Now I want to switch to Eclipse. In Eclipse I click File-New-Java Project. Then I select "Create project from existing source". After that I select the directory where all my .class files and click OK. As a result, nothing visible happens. But when I try to do the same, Eclipse tells me that that this project already exist. Where does it exist and how can I access it? By the way, in my "workspace" file nothing new appeared. Is it OK? I though my new Java Project will be there.

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  • A problem with .NET 2.0 project, using a 3.0 DLL which implements WCF services.

    - by avance70
    I made a client for accessing my WCF services in one project, and all classes that work with services inherit from this class: public abstract class ServiceClient<TServiceClient> : IDisposable where TServiceClient : ICommunicationObject This class is where I do stuff like disposing, logging when the client was called, etc. some common stuff which all service classes would normally do. Everything worked fine, until I got the task to implement this on an old system. I got into a problem when I used this project (DLL) in an other project which cannot reference System.ServiceModel (since it's an old .NET 2.0 software that I still maintain, and upgrading it to 3.0 is out of the question). Here, if I omit where TServiceClient : ICommunicationObject then the project can build, but the ServiceClient cannot use, for example, client.Close() or client.State So, is my only solution to drop the where statement, and rewrite the service classes?

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  • how does an object knows about its parent in javascript

    - by alter
    Lets suppose I made a class called Person. var Person = function(fname){this.fname = fname;}; pObj is the object I made from this class. var pObj = new Person('top'); now I add one property to Person class, say lname. Person.prototype.lname = "Thomsom"; now pObj.lname gets me "Thomson". My question is that, when pObj didn't find the property lname in it, how does it know where to look for.

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  • INSERT SQL in Java

    - by Pierre
    Hello. I have a Java application and I want to use SQL database. I have a class for my connection : public class SQLConnection{ private static String url = "jdbc:postgresql://localhost:5432/table"; private static String user = "postgres"; private static String passwd = "toto"; private static Connection connect; public static Connection getInstance(){ if(connect == null){ try { connect = DriverManager.getConnection(url, user, passwd); } catch (SQLException e) { JOptionPane.showMessageDialog(null, e.getMessage(), "Connection Error", JOptionPane.ERROR_MESSAGE); } } return connect; } } And now, in another class I succeeded to print my values but when I attempt to insert a value nothing is happening ... Here's my code : try { Statement state = SQLConnection.getInstance().createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY); Statement state2 = SQLConnection.getInstance().createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_UPDATABLE); state2.executeUpdate("INSERT INTO table(field1) VALUES (\"Value\")"); // Here's my problem ResultSet res = state.executeQuery("SELECT * FROM plateau");

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  • How to return a 'read-only' copy of a vector

    - by michael
    Hi, I have a class which has a private attribute vector rectVec; class A { private: vector<Rect> rectVec; }; My question is how can I return a 'read-only' copy of my Vector? I am thinking of doing this: class A { public: const vect<Rect>& getRectVec() { return rectVect; } } Is that the right way? I am thinking this can guard against the callee modify the vector(add/delete Rect in vector), what about the Rect inside the vector?

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  • Setting custom control properties

    - by Rob
    I though it would be very simple but I can not get it today. I have a user control, with a grid control contained in it. public Unit Width { get { return CustomerGrid.Width; } set { CustomerGrid.Width = value; } } I expose the width property and when I set it in the designer it works at run-time but not design time. What class do I inherit from or method to override to get my controls to function at design time. Note I tried to inherit from WebControl but got the message Make sure that the class defined in this code file matches the 'inherits' attribute, and that it extends the correct base class

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  • Calling from a parent file in python

    - by Teifion
    I have a file called main.py and a file called classes.py main.py contains the application and what's happening while class.py contains some classes. main.py has the following code main.py import classes def addItem(text): print text myClass = classes.ExampleClass() And then we have classes.py classes.py class ExampleClass (object): def __init__(self): addItem('bob') Surprisingly enough that's not the actual code I am using because I've stripped out anything that'd get in the way of you seeing what I want to do. I want to be able to call a method that's defined in main.py from a class within classes.py. How do I do this? Thanks in advance

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  • Whats the best to way convert a set of Java objects to another set of objects?

    - by HDave
    Basic Java question here from a real newbie. I have a set of Java objects (of class "MyClass") that implement a certain interface (Interface "MyIfc"). I have a set of these objects stored in a private variable in my class that is declared as follows: protected Set<MyClass> stuff = new HashSet<MyClass>(); I need to provide a public method that returns this set as a collection of objects of type "MyIfc". public Collection<MyIfc> getMyStuff() {...} How do I do the conversion? The following line gives me an error that it can't do the conversion. I would have guessed the compiler knew that objects of class MyClass implemented MyIfc and therefore would have handled it. Collection<MyIfc> newstuff = stuff; Any enlightenment is appreciated.

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  • When can we mock an object and its methods?

    - by Shailendra
    I am novice to the Moq and unit testing. I have to write unit tests to a lot of classes which has the objects of other classes. can i mock the methods of the class objects. Here is the exact scenerio- I have a class two classes A and B and A has a private object of B and in a method of A i am internally calling the method of B and then doing some calculation and returning the result. Can i mock the method of B in this scenerio? Please try to give me full detail about the conditions where i can mock the methods and functions of the class. Thanx

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  • Simple OOP-related question.

    - by M4design
    This question came to my mind quite a few times. Let my explain my question through an example. Say I've got two classes: 1- Grid. 2- Cell. Now the location of the cell 'should' be stored in the grid class, not in the cell class itself. Say that the cell wanted to get its location through a method in the grid. How can it do that? Keep in mind that the cell was created/initialised by the Grid class. What good OO approach to solve this problem? Thank you

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  • C#: Storting Instance of Objects in (Hashtable)

    - by DaGambit
    Hi I tried filling a Hashtable in the following way: ResearchCourse resCourse= new ResearchCourse();//Class Instance resCourse.CID="RC1000"; resCourse.CName="Rocket Science"; TaughtCourse tauCourse= new TaughtCourse();//Class Instance tauCourse.CID="TC1000"; tauCourse.CName="Marketing"; Hashtable catalog = new Hashtable(); catalog.Add("1", "resCourse.CID"); catalog.Add("2", "tauCourse.CID"); foreach (DictionaryEntry de in catalog) { Console.WriteLine("{0}, {1}", de.Key, de.Value); } Output Result to Console was: 1, resCourse.CID 2, tauCourse.CID Expected Result to be: 1, RC1000 2, TC2000 What am I misunderstanding about Hashtables? What is an easy way for the Hashtable to store the class instance and its values?

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  • What is dbReferenceProperty?

    - by user246114
    Hi, In the python app engine docs, I see something called dbReferenceProperty. I can't understand what it is, or how it's used. I'm using the java interface to app engine, so I'm not sure if there's an equivalent. I'm interested in it because it sounds like some sort of pseudo-join, where we can point a property of a class to some other object's value - something like if we had: class User { private String mPhotoUrl; private String mPhone; private String mState; private String mCountry; .. etc .. } class UserLite { @ReferenceProperty User.mPhotoUrl; private String mPhotoUrl; } then if we had to update a User object's mPhotoUrl value, the change would somehow propagate out to all UserLite instances referencing it, rather than having to update every UserLite object instance manually, Thanks

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  • Which is the best and appropriate way to write the code in Winforms ?

    - by Harikrishna
    What is the best way to write the code ? (1) Like directly writing the code in the button_click() event. or (2) Make the function of that code which I write in button_click() event and write this function in one class and then that function I should call in the button_Click() event.Like is it called three-tired approach to write the code ? Like in button_Click() event I write the code to save the records in csv file from datatable.So I should write that code in button_Click() event or I should make one new function and one new class and write that code in that function which is the new class and calling that function in button_Click() event. This is only one example but I am talking about all the code written in my application that which is the appropriate and best way to write the code and what are the benefits ? Note that I write the code in Winforms with c#.

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  • Yahoo Astra flash component error BaseScrollPane not found

    - by Chris
    I'm trying to use the Astra library from Yahoo but I'm getting an error saying the base class BaseScrollPane is not found. It appears to be imported from fl.containers.BaseScrollPane, which leads me to believe it should be a part of the base flash 10 library and therefore should be available, but it appears to be missing. Is this part of a separate package from somewhere? Update: For what it's worth, I found the actual class files in the Configuration/Component Source folder on my hard drive, but adding that to the class path (as well as the Components directory) did no good. I ended up fixing the issue by dragging a scroll pane component to the stage from the Components window and then deleting it, but I'm not sure what exactly that action changed that made it work, and would like to know for future reference.

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  • Reference to an instance method of a particular object

    - by Andrey
    In the following code, if i try to pass method reference using the class name, works. But passing the reference variable compiler gives an error, i do not understand why? public class User { private String name; public User(String name) { this.name = name; } public void printName() { System.out.println(name); } } public class Main { public static void main(String[] args) { User u1 = new User("AAA"); User u2 = new User("BBB"); User u3 = new User("ZZZ"); List<User> userList = Arrays.asList(u1, u2, u3); userList.forEach(User::printName); // works userList.forEach(u1::printName); // compile error } } Thanks,

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  • ActiveRecord has_many and polymorphic

    - by leomayleomay
    I've came into a problem while working with AR and polymorphic, here's the description, class Base < ActiveRecord::Base; end class Subscription < Base set_table_name :subscriptions has_many :posts, :as => :subscriptable end class Post < ActiveRecord::Base belongs_to :subscriptable, :polymorphic => true end in the console, >> s = Subscription.create(:name => 'test') >> s.posts.create(:name => 'foo', :body => 'bar') and it created a Post like: #<Post id: 1, name: "foo", body: "bar", subscriptable_type: "Base", subscriptable_id: 1, created_at: "2010-05-10 12:30:10", updated_at: "2010-05-10 12:30:10"> the subscriptable_type is Base but Subscription, anybody can give me a hand on this?

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  • How do you extend a Ruby module with macro-like metaprogramming methods?

    - by Ian Terrell
    Consider the following extension (the pattern popularized by several Rails plugins over the years): module Extension def self.included(recipient) recipient.extend ClassMethods recipient.class_eval { include InstanceMethods } end module ClassMethods def macro_method puts "Called macro_method within #{self.name}" end end module InstanceMethods def instance_method puts "Called instance_method within #{self.object_id}" end end end If you wished to expose this to every class, you can do the following: Object.send :include, Extension Now you can define any class and use the macro method: class FooClass macro_method end #=> Called macro_method within FooClass And instances can use the instance methods: FooClass.new.instance_method #=> Called instance_method within 2148182320 But even though Module.is_a?(Object), you cannot use the macro method in a module: module FooModule macro_method end #=> undefined local variable or method `macro_method' for FooModule:Module (NameError) This is true even if you explicitly include the original Extension into Module with Module.send(:include, Extension). How do you add macro like methods to Ruby modules?

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  • How to load modules in Java

    - by gerardorn
    I'm building a server that loads modules. Each module is a .jar file. Inside the jar there's all the classes that the module needs. The server needs to read the jar, find the main class (it doesnt have the main method on it is just the class that makes the module work but not as a different program), build an object of that class and store it in a vector of modules so that it can acces to a specific module depending on the job to be done. How can I do that? As far as the server, it is listening and receiving request, but there's no modules to delegate the job to, since my vector of modules is empty.

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  • placing image as div background

    - by Lucka
    How can I place only an image in a div as background image, and add url link to it. Currenty I'm doing it this way: <div class="image"><a href="example.com"><img src="books.png" alt="Test" /></a></div> I want to do something like following, but its not working (the image does not appear). <div class="image"><a href="example.com"><span class="books"></span></a></div> Thanks.

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