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  • Do I correctly understand what a class is?

    - by Matt
    I've had trouble finding a clear, concise laymans definition of a class. Usually, they give general ideas without specifically spelling it out, and I'm wondering if I'm understanding this correctly. As I understand it, a class is the set of code that controls an object. For example, in an app that has a button for 'Yes' and a button for 'No', and a text box for output, the code that tells the computer what to do when the user uses the Yes button is one class, the code for hitting No is another class, and an object is the two buttons and what they do together to influence the output box. Am I right, or am I confusing terms here? Thanks

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  • java: can't use constructors in abstract class

    - by ufk
    Hi. I created the following abstract class for job scheduler in red5: package com.demogames.jobs; import com.demogames.demofacebook.MysqlDb; import org.red5.server.api.IClient; import org.red5.server.api.IConnection; import org.red5.server.api.IScope; import org.red5.server.api.scheduling.IScheduledJob; import org.red5.server.api.so.ISharedObject; import org.apache.log4j.Logger; import org.red5.server.api.Red5; /** * * @author ufk */ abstract public class DemoJob implements IScheduledJob { protected IConnection conn; protected IClient client; protected ISharedObject so; protected IScope scope; protected MysqlDb mysqldb; protected static org.apache.log4j.Logger log = Logger .getLogger(DemoJob.class); protected DemoJob (ISharedObject so, MysqlDb mysqldb){ this.conn=Red5.getConnectionLocal(); this.client = conn.getClient(); this.so=so; this.mysqldb=mysqldb; this.scope=conn.getScope(); } protected DemoJob(ISharedObject so) { this.conn=Red5.getConnectionLocal(); this.client=this.conn.getClient(); this.so=so; this.scope=conn.getScope(); } protected DemoJob() { this.conn=Red5.getConnectionLocal(); this.client=this.conn.getClient(); this.scope=conn.getScope(); } } Then i created a simple class that extends the previous one: public class StartChallengeJob extends DemoJob { public void execute(ISchedulingService service) { log.error("test"); } } The problem is that my main application can only see the constructor without any parameters. with means i can do new StartChallengeJob() why doesn't the main application sees all the constructors ? thanks!

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  • General question about Ruby singleton class

    - by Dex
    module MyModule def my_method; 'hello'; end end class MyClass class << self include MyModule end end MyClass.my_method # => "hello I'm unsure why "include MyModule" needs to be in the singleton class in order to be called using just MyClass. Why can't I go: X = MyClass.new X.my_method

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  • ruby/datamapper: Refactor class methods to module

    - by DeSchleib
    Hello, i've the following code and tried the whole day to refactor the class methods to a sperate module to share the functionality with all of my model classes. Code (http://pastie.org/974847): class Merchant include DataMapper::Resource property :id, Serial [...] class << self @allowed_properties = [:id,:vendor_id, :identifier] alias_method :old_get, :get def get *args [...] end def first_or_create_or_update attr_hash [...] end end end I'd like to archive something like: class Merchant include DataMapper::Resource include MyClassFunctions [...] end module MyClassFunctions def get [...] def first_or_create_or_update[...] end => Merchant.allowed_properties = [:id] => Merchant.get( :id=> 1 ) But unfortunately, my ruby skills are to bad. I read a lot of stuff (e.g. here) and now i'm even more confused. I stumbled over the following two points: alias_method will fail, because it will dynamically defined in the DataMapper::Resource module. How to get a class method allowed_properties due including a module? What's the ruby way to go? Many thanks in advance.

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  • Compare Database container and class container

    - by Mohit Deshpande
    I am using a SQL Server database in my current project. I was watching the MVC Storefront videos (specifically the repository pattern) and I noticed that Rob (the creator of MVC Storefront) used a class called Category and Product, instead of a database and I have notice that using LINQ-SQL or ADO.NET, that a class is generated. Is there an advantage to using a class over a database to store information? Or is it the other way around? Or are they even comparable?

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  • OOP - Handling Automated Instances of a Class - PHP

    - by dscher
    This is a topic that, as a beginner to PHP and programming, sort of perplexes me. I'm building a stockmarket website and want users to add their own stocks. I can clearly see the benefit of having each stock be a class instance with all the methods of a class. What I am stumped on is the best way to give that instance a name when I instantiate it. If I have: class Stock() { ....doing stuff..... } what is the best way to give my instances of it a name. Obviously I can write: $newStock = new Stock(); $newStock.getPrice(); or whatever, but if a user adds a stock via the app, where can the name of that instance come from? I guess that there is little harm in always creating a new child with $newStock = new Stock() and then storing that to the DB which leads me to my next question! What would be the best way to retrieve 20 user stocks(for example) into instances of class Stock()? Do I need to instantiate 20 new instances of class Stock() every time the user logs in or is there something I'm missing? I hope someone answers this and more important hope a bunch of people answer this and it somehow helps someone else who is having a hard time wrapping their head around what probably leads to a really elegant solution. Thanks guys!

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  • Unable to use 'class' as a key in NSDictionary with Xcode 4.5

    - by Vivin Paliath
    I'm trying to use a class as a key in an NSDictionary. I looked at the answer to this question and what I have is pretty much the same; I'm using setObject: forKey:. However, XCode complains, saying Incompatible pointer types sending 'Class' to parameter of type 'id<NSCopying>'. The call I have is: [_bugTypeToSerializerDictionary setObject: bugToStringSerializer forKey: [bugToStringSerializer serializedObjectType]]; bugToStringSerializer is an instance of BugToStringSerializer whose concrete implementations implement serializedObjectType. An example of a concrete implementation looks like this: - (Class) serializedObjectType { return [InfectableBug class]; } What am I doing wrong here?

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  • Add LINQ Auto-Generated Value Marker [Column(IsDbGenerated=true)] in Buddy Class

    - by Alex
    Hello, is it possible to decorate a field of a LINQ generated class with [Column(IsDbGenerated=true)] using a buddy class (which is linked to the LINQ class via [MetadataType(typeof(BuddyMetadata))]) ? My goal is to be able to clear and repopulate the LINQ ORM designer without having to set the "Auto Generate Value" property manually every time to re-establish the fact that certain columns are autogenerated. Thanks!

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  • jQuery Validation using the class instead of the name value

    - by Matt
    Hi, I'd like to validate a form using the jquery validate plugin, but I'm unable to use the 'name' value within the html - as this is a field also used by the server app. Specifically, I need to limit the number of checkboxes checked from a group. (Maximum of 3.) All of the examples I have seen, use the name attribute of each element. What I'd like to do is use the class instead, and then declare a rule for that. html This works: <input class="checkBox" type="checkbox" id="i0000zxthy" name="salutation" value="1" /> This doesn't work, but is what I'm aiming for: <input class="checkBox" type="checkbox" id="i0000zxthy" name="i0000zxthy" value="1" /> javascript: var validator = $(".formToValidate").validate({ rules:{ "salutation":{ required:true, }, "checkBox":{ required:true, minlength:3 } } }); Is it possible to do this - is there a way of targeting the class instead of the name within the rules options? Or do I have to add a custom method? Cheers, Matt

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  • jQuery Checkbox class attribute

    - by mike
    how do you access the class attribute of a in a jQuery selector statement? for example <asp:CheckBox runat="server" ID="cbTest" Text="Cb Test" FieldName="1st Test Check Box" class="toggleBox"/> this: $(':checkbox').toggleAttr("checked", true, false) accesses the checkbox and applies a custom function to the checked attribute but if i want to filter based on a certain class how do i access/filter based on that?

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  • python class decorator question?

    - by nsharish
    decorator 1: def dec(f): def wrap(obj, *args, **kwargs): f(obj, *args,**kwargs) return wrap decorator 2: class dec: def __init__(self, f): self.f = f def __call__(self, obj, *args, **kwargs): self.f(obj, *args, **kwargs) A sample class, class Test: @dec def disp(self, *args, **kwargs): print(*args,**kwargs) The follwing code works with decorator 1 but not with decorator 2. a = Test() a.disp("Message") I dont understand why decorator 2 is not working here. Can someone help me with this?

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  • Problem deriving a user control from an abstract base class in website project

    - by Sprintstar
    In a Visual Studio website, I have created a user control. This control is derived from a class (in App_Code) that is itself derived from System.Web.UI.UserControl. This is an abstract class with an abstract method. I then try to implement that method in the user control, but I get the following errors from Visual Studio: Error 1 'WebUserControl.AbstractMethod()': no suitable method found to override C:\Users\User\Documents\Visual Studio 2010\WebSites\Delme\WebUserControl.ascx.cs 10 28 C:\...\Delme\ Error 2 'WebUserControl' does not implement inherited abstract member 'AbstractBaseClass.AbstractMethod()' c:\Users\User\AppData\Local\Temp\Temporary ASP.NET Files\delme\0eebaa86\f1a48678\App_Web_nrsbzxex.0.cs 14 Error 1 says that my override of the abstract method is invalid, it doesn't recognise the abstract method in the base class. Error 2 says that the partial class automatically built by asp.net doesn't implement the abstract method! Note that this works fine when the code is used in a Web Application project. Why is this happening?

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  • Xerces C++ SAX Parsing Problem: expected class-name before '{' token

    - by aduric
    I'm trying to run through an example given for the C++ Xerces XML library implementation. I've copied the code exactly, but I'm having trouble compiling it. error: expected class-name before '{' token I've looked around for a solution, and I know that this error can be caused by circular includes or not defining a class before it is used, but as you can see from the code, I only have 2 files: MySAXHandler.hpp and MySAXHandler.cpp. However, the MySAXHandler class is derived from HandlerBase, which is included. MyHandler.hpp #include <xercesc/sax/HandlerBase.hpp> class MySAXHandler : public HandlerBase { public: void startElement(const XMLCh* const, AttributeList&); void fatalError(const SAXParseException&); }; MySAXHandler.cpp #include "MySAXHandler.hpp" #include <iostream> using namespace std; MySAXHandler::MySAXHandler() { } void MySAXHandler::startElement(const XMLCh* const name, AttributeList& attributes) { char* message = XMLString::transcode(name); cout << "I saw element: "<< message << endl; XMLString::release(&message); } void MySAXHandler::fatalError(const SAXParseException& exception) { char* message = XMLString::transcode(exception.getMessage()); cout << "Fatal Error: " << message << " at line: " << exception.getLineNumber() << endl; XMLString::release(&message); } I'm compiling like so: g++ -L/usr/local/lib -lxerces-c -I/usr/local/include -c MySAXHandler.cpp I've looked through the HandlerBase and it is defined, so I don't know why I can't derive a class from it? Do I have to override all the virtual functions in HandlerBase? I'm kinda new to C++. Thanks in advance.

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  • Seam @Factory in abstract base class?

    - by Shadowman
    I've got a series of web actions I'm implementing in Seam to perform create, read, update, etc. operations. For my read/update/delete actions, I'd like to have individual action classes that all extend an abstract base class. I'd like to put the @Factory method in the abstract base class to retrieve the item that is to be acted upon. For example, I have this as the base class: public abstract class BaseAction { @In(required=false)@Out(required=false) private MyItem item=null; public MyItem getItem(){...} public void setItem(...){...} @Factory("item") public void initItem(){...} } My subclasses would extend BaseAction, so that I don't have to repeat the logic to load the item that is to be viewed, deleted, updated, etc. However, when I start my application, Seam throws errors saying I have declared multiple @Factory's for the same object. Is there any way around this? Is there any way to provide the @Factory in the base class without encoutnering these errors?

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  • Help with abstract class in Java with private variable of type List<E>

    - by Nazgulled
    Hi, It's been two years since I last coded something in Java so my coding skills are bit rusty. I need to save data (an user profile) in different data structures, ArrayList and LinkedList, and they both come from List. I want to avoid code duplication where I can and I also want to follow good Java practices. For that, I'm trying to create an abstract class where the private variables will be of type List<E> and then create 2 sub-classes depending on the type of variable. Thing is, I don't know if I'm doing this correctly, you can take a look at my code: Class: DBList import java.util.List; public abstract class DBList { private List<UserProfile> listName; private List<UserProfile> listSSN; public List<UserProfile> getListName() { return this.listName; } public List<UserProfile> getListSSN() { return this.listSSN; } public void setListName(List<UserProfile> listName) { this.listName = listName; } public void setListSSN(List<UserProfile> listSSN) { this.listSSN = listSSN; } } Class: DBListArray import java.util.ArrayList; public class DBListArray extends DBList { public DBListArray() { super.setListName(new ArrayList<UserProfile>()); super.setListSSN(new ArrayList<UserProfile>()); } public DBListArray(ArrayList<UserProfile> listName, ArrayList<UserProfile> listSSN) { super.setListName(listName); super.setListSSN(listSSN); } public DBListArray(DBListArray dbListArray) { super.setListName(dbListArray.getListName()); super.setListSSN(dbListArray.getListSSN()); } } Class: DBListLinked import java.util.LinkedList; public class DBListLinked extends DBList { public DBListLinked() { super.setListName(new LinkedList<UserProfile>()); super.setListSSN(new LinkedList<UserProfile>()); } public DBListLinked(LinkedList<UserProfile> listName, LinkedList<UserProfile> listSSN) { super.setListName(listName); super.setListSSN(listSSN); } public DBListLinked(DBListLinked dbListLinked) { super.setListName(dbListLinked.getListName()); super.setListSSN(dbListLinked.getListSSN()); } } 1) Does any of this make any sense? What am I doing wrong? Do you have any recommendations? 2) It would make more sense for me to have the constructors in DBList and calling them (with super()) in the subclasses but I can't do that because I can't initialize a variable with new List<E>(). 3) I was thought to do deep copies whenever possible and for that I always override the clone() method of my classes and code it accordingly. But those classes never had any lists, sets or maps on them, they only had strings, ints, floats. How do I do deep copies in this situation?

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  • C# - What should I do when every inherited class needs getter from base class, but setter only for O

    - by msfanboy
    Hello, I have a abstract class called WizardViewModelBase. All my WizardXXXViewModel classes inherit from the base abstract class. The base has a property with a getter. Every sub class needs and overrides that string property as its the DisplayName of the ViewModel. Only ONE ViewModel called WizardTimeTableWeekViewModel needs a setter because I have to set wether the ViewModel is a timetable for week A or week B. Using 2 ViewModels like WizardTimeTableWeekAViewModel and WizardTimeTableWeekBViewModel would be redundant. I do not want to override the setter in all other classes as they do not need a setter. Can I somehow tell the sub class it needs not to override the setter? Or any other suggestion? With interfaces I would be free to use getter or setter but having many empty setter properties is not an option for me.

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  • PHP echo query result in Class??

    - by Jerry
    Hi all I have a question about PHP Class. I am trying to get the result from Mysql via PHP. I would like to know if the best practice is to display the result inside the Class or store the result and handle it in html. For example, display result inside the Class class Schedule { public $currentWeek; function teamQuery($currentWeek){ $this->currentWeek=$currentWeek; } function getSchedule(){ $connection = mysql_connect(DB_SERVER,DB_USER,DB_PASS); if (!$connection) { die("Database connection failed: " . mysql_error()); } $db_select = mysql_select_db(DB_NAME,$connection); if (!$db_select) { die("Database selection failed: " . mysql_error()); } $scheduleQuery=mysql_query("SELECT guest, home, time, winner, pickEnable FROM $this->currentWeek ORDER BY time", $connection); if (!$scheduleQuery){ die("database has errors: ".mysql_error()); } while($row=mysql_fetch_array($scheduleQuery, MYSQL_NUMS)){ //display the result..ex: echo $row['winner']; } mysql_close($scheduleQuery); //no returns } } Or return the query result as a variable and handle in php class Schedule { public $currentWeek; function teamQuery($currentWeek){ $this->currentWeek=$currentWeek; } function getSchedule(){ $connection = mysql_connect(DB_SERVER,DB_USER,DB_PASS); if (!$connection) { die("Database connection failed: " . mysql_error()); } $db_select = mysql_select_db(DB_NAME,$connection); if (!$db_select) { die("Database selection failed: " . mysql_error()); } $scheduleQuery=mysql_query("SELECT guest, home, time, winner, pickEnable FROM $this->currentWeek ORDER BY time", $connection); if (!$scheduleQuery){ die("database has errors: ".mysql_error()); // create an array } $ret = array(); while($row=mysql_fetch_array($scheduleQuery, MYSQL_NUMS)){ $ret[]=$row; } mysql_close($scheduleQuery); return $ret; // and handle the return value in php } } Two things here: I found that returned variable in php is a little bit complex to play with since it is two dimension array. I am not sure what the best practice is and would like to ask you experts opinions. Every time I create a new method, I have to recreate the $connection variable: see below $connection = mysql_connect(DB_SERVER,DB_USER,DB_PASS); if (!$connection) { die("Database connection failed: " . mysql_error()); } $db_select = mysql_select_db(DB_NAME,$connection); if (!$db_select) { die("Database selection failed: " . mysql_error()); } It seems like redundant to me. Can I only do it once instead of calling it anytime I need a query? I am new to php class. hope you guys can help me. thanks.

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  • Exception when access inner class reflectively

    - by MikeJiang
    Hi Folk, Here is a sample java program. I wonder why the two approaches reslut different stories. Is it a bug or kind of bitter java feature? And I run the sample upon java 1.5 package test; public class TestOut{ public static void main(String[] args){ new TestIn();//it works Class.forName("test.TestOut$TestIn").newInstance();// throw IllegalAccessException } private static class TestIn{} }

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  • Ruby on Rails with_option cannot call class method

    - by Dmitri
    I have a problem calling class method from the with_option block with validations: Model: class Model < ActiveRecord::Base attr_accessible :field with_options :if => "<not important>" do |step| ... bunch of validations step.validates :field, :inclusion => {:within => Model.field} end private self.field (1..10) end end And it returns: undefined method `field' for #Class:0x5f394a8 self.class.field also doesn't work. What is wrong with it ? How to fix it ? Big big thanks!

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  • SWIG-Lua question on class returning another class

    - by John Smith
    I am concreting a question I had earlier. I have two classes in C++ and I use SWIG to wrap them. A method in one class can return a pointer to the other class. How can I get Lua to see it as more than just a userdata? More concretely: I have class fruit { int numberofseeds; //some other stuff about fruit constructors etc... public: getseedcount() { return numberofseeds; } } class tree { fruit * apple; public: //constructors and whatnot fruit * getfruit() { return apple; } } I wrap these two class with SWIG so I can access them in Lua So I can get in Lua the object x=pomona.tree(grannysmith). My question now is: How can I arrange for things so that when I type y=x:getfruit() I will get a pomona:fruit type object? Where I can write something line y:getseedcount()? At the moment all I get is userdata which not edible.

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  • Class interaction

    - by user1264391
    Ok so I'm doing a simulation about a "Mall" I have many classes in the same "level" which corresponds to each person's personality. For example I have the class: clown, thief, assassin, materialist, etc. in the same level And a father class called Clients. In the Client class I have some methods for eating,walking, etc. and each specific class has a specific method, the thief steals, assassin kills, etc. I was wondering how could I put every "client" in a list and still cast every specific method?

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  • How to implement an abstract class in ruby?

    - by Chirantan
    I know there is no concept of abstract class in ruby. But if at all it needs to be implemented, how to go about it? I tried something like... class A def self.new raise 'Doh! You are trying to instantiate an abstract class!' end end class B < A ... ... end But when I try to instantiate B, it is internally going to call A.new which is going to raise the exception. Also, modules cannot be instantiated but they cannot be inherited too. making the new method private will also not work. Any pointers?

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  • Python: saving and loading a class definition

    - by Peterstone
    Hi! I am interested in saving and load objects using the pickle module as you can read in a question I asked before: Python: Errors saving and loading objects with pickle module Someone commment: 1, In an other way: the error is raise because pickle wanted to load an instance of the class Fruits and search for the class definition where it was defined, but it didn't find it so it raise the error Now I want to save and load a class definition in order to solve the problem I describe in the question mentioned before. Thank you so much!

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  • iPhone - extending a class delegate

    - by Digital Robot
    OK, I know how to create a class extension, using something like that: on .h @interface UIButton (myExtensionName) // my extended methods @end and then on .m @implementation UIButton (myExtensionName) // my implementations @end But how do I declare the extended delegates I may create? If this was a normal class I would do @protocol myExtensionName <NSObject> // my delegate declarations @end but how do I do that on a class extension? thanks

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