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  • Obtaining reference to Class instance by string name - VB.NET

    - by Jeff Williams
    Is it possible using Reflection or some other method to obtain a reference to a specific class instance from the name of that class instance? For example the framework for the applications i develop heavily uses public class instances such as: Public bMyreference as MyReference = new MyReference Then throughout the application bMyReference is used by custom controls and code. One of the properties of the custom controls is the "FieldName" which references a Property in these class instances (bMyReference.MyField) as a string. What i would like to be able to do is analyze this string "bMyReference.MyField" and then refer back to the actual Instance/Property. In VB6 I would use an EVAL or something simular to convert the string to an actual object but this obviously doesn't work in VB.net What I'm picturing is something like this Dim FieldName as String = MyControl.FieldName ' sets FielName to bMyReference.MyField Dim FieldObject() as String = FieldName.Split(".") ' Split into the Object / Property Dim myInstance as Object = ......... ' Obtain a reference to the Instance and set as myInstance Dim myProperty = myInstance.GetType().GetProperty(FieldObject(1))

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  • LVM mirroring VS RAID1

    - by syrenity
    Hi. Having learned a bit about LVM mirroring, I thought about replacing the current RAID-1 scheme I'm using to gain some flexibility. Problem is that according to what I found on the Internet, LVM is: 1) Slower then RAID-1, at least in reading (as only single volume being used for reading). 2) Non-reliable on power interrupts, and requires disk cache disabling for prevention of data loss. http://www.joshbryan.com/blog/2008/01/02/lvm2-mirrors-vs-md-raid-1/ Also it seems, at least to several setup guides I read (http://www.tcpdump.com/kb/os/linux/lvm-mirroring/intro.html), that one actually requires a 3rd disk for storing the LVM log. This makes the setup completely unusable on 2 disks installations, and lowers the amount of used mirror disks on higher amount of disks. Can anyone comment the above facts, and let me know his experience of using LVM mirroring? Thanks.

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  • Encapsulating user input of data for a class (C++)

    - by Dr. Monkey
    For an assignment I've made a simple C++ program that uses a superclass (Student) and two subclasses (CourseStudent and ResearchStudent) to store a list of students and print out their details, with different details shown for the two different types of students (using overriding of the display() method from Student). My question is about how the program collects input from the user of things like the student name, ID number, unit and fee information (for a course student) and research information (for research students): My implementation has the prompting for user input and the collecting of that input handled within the classes themselves. The reasoning behind this was that each class knows what kind of input it needs, so it makes sense to me to have it know how to ask for it (given an ostream through which to ask and an istream to collect the input from). My lecturer says that the prompting and input should all be handled in the main program, which seems to me somewhat messier, and would make it trickier to extend the program to handle different types of students. I am considering, as a compromise, to make a helper class that handles the prompting and collection of user input for each type of Student, which could then be called on by the main program. The advantage of this would be that the student classes don't have as much in them (so they're cleaner), but also they can be bundled with the helper classes if the input functionality is required. This also means more classes of Student could be added without having to make major changes to the main program, as long as helper classes are provided for these new classes. Also the helper class could be swapped for an alternative language version without having to make any changes to the class itself. What are the major advantages and disadvantages of the three different options for user input (fully encapsulated, helper class or in the main program)?

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  • 2 Classes need each other declared C++

    - by Prodigga
    I have a "Game" class which holds all the games settings and manages the game. I have a "Grid" class which is the grid the game is played on. The "Game" class initializes a "Grid" object as one of its members (passing itself ("this") as one of the parameters for "Grid"s constructor).. The "Grid" object therefor needs to deal with a "Game*" pointer. To do this it needs to know what "Game" is; i need to declare it before "Grid". But "Game" uses "Grid"...so it also needs "Grid" declared before it. so confused on how to include headers/etc correctly here..

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  • creative way for implementing Data object with its corresponding business logic class in java

    - by ekeren
    I have a class that need to be serialized (for both persistentcy and client-server communication) for simplicity's sake let's call the classes Business a BusinessData and I prefix for their Interfaces. All the getter and setter are delegated from Business class to BusinessData class. I thought about implementing IBusinessData interface that will contain all the getter and setters and IBusiness interface that will extend it. I can either make Business extend BuisnessData so I will not need to implement all getter and setter delegates, or make some abstract class ForwardingBusinessData that will only delegate getter and setters. Any of the above option I lose my hierarchy freedom, do any of you have any creative solutions for this problem... I also reviewed DAO pattern: http://java.sun.com/blueprints/patterns/DAO.html

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  • Java - Could not find the main class?

    - by asmo
    I'm having a hard-time with a Java error. I'm getting this when double-clicking on my compiled project Jar file in order to run it: Could not find the main class: testPackage.testFrame. Program will exit. However, my main class is cleary defined in the project properties. Furthermore, everything works fine when I run the project directly from NetBeans. I'm using the ip2c.jar third-party library to determine countries from IP addresses. If I comment the class that is using the ip2c.jar file, I don't get the error. How can a third-party library be preventing the JVM from finding my main class?

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  • StructureMap - Injecting a dependency into a base class?

    - by David
    In my domain I have a handful of "processor" classes which hold the bulk of the business logic. Using StructureMap with default conventions, I inject repositories into those classes for their various IO (databases, file system, etc.). For example: public interface IHelloWorldProcessor { string HelloWorld(); } public class HelloWorldProcessor : IHelloWorldProcessor { private IDBRepository _dbRepository; public HelloWorldProcessor(IDBRepository dbRepository) { _dbRepository = dbrepository; } public string HelloWorld(){ return _dbRepository.GetHelloWorld(); } } Now, there are some repositories that I'd like to be available to all processors, so I made a base class like this: public class BaseProcessor { protected ICommonRepository _commonRepository; public BaseProcessor(ICommonRepository commonRepository) { _commonRepository = commonRepository; } } But when my other processors inherit from it, I get a compiler error on each one saying that there's no constructor for BaseProcessor which takes zero arguments. Is there a way to do what I'm trying to do here? That is, to have common dependencies injected into a base class that my other classes can use without having to write the injections into each one?

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  • How can i use 'log' inside a src/groovy/ class

    - by firnnauriel
    I'm encountering this error: groovy.lang.MissingPropertyException: No such property: log for class: org.utils.MyClass Here's the content of the class: package org.utils class MyClass { int organizationCount = 0 public int getOrganizationCount(){ log.debug "There are ${organizationCount} organization(s) found." return organizationCount } } Do i need to add an import statement? What do i need to add? Note that the class is located in src/groovy/org/utils. I know that the 'log' variable is accessible in controllers, services, etc. Not sure in 'src' classes. Thanks.

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  • Base class with abstract subclasses in C# ?

    - by Nick Brooks
    public abstract class Request { public class Parameters { //Threre are no members here //But there should be in inherited classes } public Request() { parameters = new Parameters(); } public Parameters parameters; } Two questions: How do I make it so I can add stuff to the constructor but the original constructor will still be executed? How do I make it so the subclasses can add members to the Parameters class?

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  • Overriding the admin Media class

    - by shacker
    Given an admin media class that sets up a rich text editor, like: class TutorialAdmin(admin.ModelAdmin): fields... class Media: js = ['/paths/to/tinymce.js',] I would like the ability to selectively override js depending on a field value in the model it references. I've added a "use_editor" boolean to the Tutorial model. The question is, how can I detect whether the current instance has that bool set? I'd like to end up with something like: class Media: if self.use_editor: js = ['/path/to/tinymce.js',] else: js = '' Ideas? Thanks.

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  • selenium cannot find element with class in IE

    - by Rob
    I'm using selenium_client with cucumber, webrat + IE As you'd expect, Firefox works fine. I've tried the following: selenium.is_visible("css=#flash .flash_notice") selenium.is_visible("xpath=//*[@id='flash']/*[@class='flash_notice]") selenium.is_visible("xpath=//*[@id='flash']/*[contains(@class,'flash_notice]')") both cannot find the element. I think it must be something to do with IE, looking closer at the html selenium returns from IE... It looks like this: <UL id=flash> <LI className=flash_notice>Deleted</LI> </UL> Notice IE returns the class attribute as className, is this confusing selenium? How can I get round this so that I can use the same statement for selenium using IE and Firefox Just to confuse us even more, this example works, confirming its something to do with checking the class attribute selenium.is_visible("xpath=//*[@id='flash']/*[. =\'Deleted\']")

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  • httpURLConnection vs apache commons http

    - by Pablo Fernandez
    Hi everyone! I just wanted to know if any of you had any problems using java default HttpURLConnection class. Some kind of bug that made you switch to apache commons. Or is it just the (ugly) interface that class exposes that justifies the birth of 3rd party http lib? Disclosure: I heard some arguments against java.net having some serious problems, but I'm finding hard to believe that a class that is part of the java core distribution still has issues after several releases of the JDK

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  • Adding business logic to a domain class using a getter style method name

    - by Richard Paul
    I'm attempting to add a method to a grails domain class, e.g. class Item { String name String getReversedName() { name.reverse() } } When I attempt to load the application using grails console I get the following error: Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory':Invocation of init method failed; nested exception is org.hibernate.PropertyNotFoundException: Could not find a setter for property reversedName in class Item ... 18 more It looks like Hibernate is interpreting getReversedName() as a getter for a property, however in this case it is a derived field and hence should not be persisted. Obviously in my actual code the business logic I'm exposing is more complex but it isn't relevant to this question. I want to be able to call item.reversedName in my code/gsps. How can I provide property (getter) access to a method in a Grails domain class without Grails attempting to map it with Hibernate?

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  • Defining a recursive function in a Prototype class?

    - by btl
    I'm trying to create an image rotator class that cycles through an arbitrary number of images in an unordered list. Is it possible to define a recursive function within a class declaration? E.g: var Rotator = Class.create() { initialize: function() { do something... this.rotate(); } rotate: function() { do something... this.rotate() } }

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  • Question regarding common class

    - by Rocky Singh
    I have following two classes: public class A : System.Web.UI.WebControls.Button { public virtual string X { get { object obj = ViewState["X"]; if (obj != null) return (string)obj; return null; } set { ViewState["X"] = value; } } protected override void OnLoad(EventArgs e) { X=2; } } and public class B : System.Web.UI.WebControls.TextBox { public virtual string X { get { object obj = ViewState["X"]; if (obj != null) return (string)obj; return null; } set { ViewState["X"] = value; } } protected override void OnLoad(EventArgs e) { X=2; } } As you must be seeing the class A and B have exactly the same code , my question is how can I make a common class for it and use these two classes.

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  • Inheritance and choose constructor from base class

    - by myle
    My question is rather simple, but I am stuck. How can I choose the desired constructor from base class? // node.h #ifndef NODE_H #define NODE_H #include <vector> // definition of an exception-class class WrongBoundsException { }; class Node { public: ... Node(double, double, std::vector<double>&) throw (WrongBoundsException); ... }; #endif // InternalNode.h #ifndef INTERNALNODE_H #define INTERNALNODE_H #include <vector> #include "Node.h" class InternalNode : public Node { public: // the position of the leftmost child (child left) int left_child; // the position of the parent int parent; InternalNode(double, double, std::vector<double>&, int parent, int left_child) throw (WrongBoundsException); private: int abcd; }; #endif // InternalNode.cpp #include "InternalNode.h" #define UNDEFINED_CHILD -1 #define ROOT -1 // Here is the problem InternalNode::InternalNode(double a, double b, std::vector<double> &v, int par, int lc) throw (WrongBoundsException) : Node(a, b, v), parent(par), left_child(lc) { std::cout << par << std::endl; } I get: $ g++ InternalNode.cpp InternalNode.cpp:16: error: declaration of ‘InternalNode::InternalNode(double, double, std::vector &, int, int) throw (WrongBoundsException)’ throws different exceptions InternalNode.h:17: error: from previous declaration ‘InternalNode::InternalNode(double, double, std::vector &, int, int)’ UPDATE 0: Fixed missing : UPDATE 1: Fixed throw exception

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  • Use of type 'id' in cocoa class

    - by gotye
    Hey guys, I want to implement a class which can be used by two classes of my project. One is manipulating 'NewsRecord' objects. One is manipulating 'GalleriesRecord' objects. In another class, I may use one of the two objects so i do something like that : // header class id myNewsRecordOrGalleriesRecord; // class.m // NewsRecord and GalleriesRecord have both the title property NSLog(myNewsRecordOrGalleriesRecord.title); and i get : error : request for member 'title' in something not a structure or union any ideas :D ? Thanks. Gotye How am I supposed to do it ?

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  • Find tag that contains certain text and add a class

    - by David Gard
    I have the following HTML, and I need to add a class to both <li> and <a> where the text 'Charts' exists (so not the second line, but rather the 4th and 5th). I cannot change the output of the HTML. <div class="wp-submenu-wrap"> <div class="wp-submenu-head">Charts</div> <ul> <li class="wp-first-item"> <a class="wp-first-item" tabindex="1" href="admin.php?page=charts">Charts</a> </li> <li> <a tabindex="1" href="admin.php?page=add-chart">Add Chart</a> </li> </ul> </div> I've tried doing this by locating the <a> tag that contains the text, but it is not working. Can somebody please point me in the correct direction? Thanks. Code that I've tried - $(document).ready(function(){ if(pagenow === 'admin_page_edit-chart') { var page = $('.wp-submenu-wrap a:contains["Charts"]'); page.addClass('current'); page.parent('li').addClass('current'); } });

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  • Question of using static_cast on "this" pointer in a derived object to base class

    - by Johnyy
    Hi, this is an example taken from Effective C++ 3ed, it says that if the static_cast is used this way, the base part of the object is copied, and the call is invoked from that part. I wanted to understand what is happening under the hood, will anyone help? class Window { // base class public: virtual void onResize() { } // base onResize impl }; class SpecialWindow: public Window { // derived class public: virtual void onResize() { // derived onResize impl; static_cast<Window>(*this).onResize(); // cast *this to Window, // then call its onResize; // this doesn't work! // do SpecialWindow- } // specific stuff };

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  • xml to xsd to c# class - C# 3.0, .net 3.5

    - by uno
    Following this articlelink text one of the comments from 'zanoni' said he did it this way Using .NET 3.5: [XmlRoot] public class EmailConfiguration { [XmlElement] public string DataBoxID { get; set; } [XmlElement] public DefaultSendToAddressCollectionClass DefaultSendToAddressCollection { get; set; } } public class DefaultSendToAddressCollectionClass { [XmlElement] public string[] EmailAddress { get; set; } } How would I get my class to be as what he described? I ran the xsd tool and it is in the fashion as what shane posted in the above link [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.3038")] [System.SerializableAttribute()] [System.Diagnostics.DebuggerStepThroughAttribute()] [System.ComponentModel.DesignerCategoryAttribute("code")] [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)] [System.Xml.Serialization.XmlRootAttribute(Namespace="", IsNullable=false)] public partial class EmailConfiguration : object, System.ComponentModel.INotifyPropertyChanged { private string dataBoxIDField; private EmailConfigurationDefaultSendToAddressCollection[] defaultSendToAddressCollectionField; /// <remarks/> [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified)] public string DataBoxID { get { return this.dataBoxIDField; } set { this.dataBoxIDField = value; this.RaisePropertyChanged("DataBoxID"); } }

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  • Choosing a design pattern for a class that might change it's internal attributes

    - by the_drow
    I have a class that holds arbitrary state and it's defined like this: class AbstractFoo { }; template <class StatePolicy> class Foo : public StatePolicy, public AbstractFoo { }; The state policy contains only protected attributes that represent the state. The state might be the same for multiple behaviors and they can be replaced at runtime. All Foo objects have the same interface to abstract the state itself and to enable storing Foo objects in containers. I would like to find the least verbose and the most maintainable way to express this.

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  • functional dependencies vs type families

    - by mhwombat
    I'm developing a framework for running experiments with artificial life, and I'm trying to use type families instead of functional dependencies. Type families seems to be the preferred approach among Haskellers, but I've run into a situation where functional dependencies seem like a better fit. Am I missing a trick? Here's the design using type families. (This code compiles OK.) {-# LANGUAGE TypeFamilies, FlexibleContexts #-} import Control.Monad.State (StateT) class Agent a where agentId :: a -> String liveALittle :: Universe u => a -> StateT u IO a -- plus other functions class Universe u where type MyAgent u :: * withAgent :: (MyAgent u -> StateT u IO (MyAgent u)) -> String -> StateT u IO () -- plus other functions data SimpleUniverse = SimpleUniverse { mainDir :: FilePath -- plus other fields } defaultWithAgent :: (MyAgent u -> StateT u IO (MyAgent u)) -> String -> StateT u IO () defaultWithAgent = undefined -- stub -- plus default implementations for other functions -- -- In order to use my framework, the user will need to create a typeclass -- that implements the Agent class... -- data Bug = Bug String deriving (Show, Eq) instance Agent Bug where agentId (Bug s) = s liveALittle bug = return bug -- stub -- -- .. and they'll also need to make SimpleUniverse an instance of Universe -- for their agent type. -- instance Universe SimpleUniverse where type MyAgent SimpleUniverse = Bug withAgent = defaultWithAgent -- boilerplate -- plus similar boilerplate for other functions Is there a way to avoid forcing my users to write those last two lines of boilerplate? Compare with the version using fundeps, below, which seems to make things simpler for my users. (The use of UndecideableInstances may be a red flag.) (This code also compiles OK.) {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, UndecidableInstances #-} import Control.Monad.State (StateT) class Agent a where agentId :: a -> String liveALittle :: Universe u a => a -> StateT u IO a -- plus other functions class Universe u a | u -> a where withAgent :: Agent a => (a -> StateT u IO a) -> String -> StateT u IO () -- plus other functions data SimpleUniverse = SimpleUniverse { mainDir :: FilePath -- plus other fields } instance Universe SimpleUniverse a where withAgent = undefined -- stub -- plus implementations for other functions -- -- In order to use my framework, the user will need to create a typeclass -- that implements the Agent class... -- data Bug = Bug String deriving (Show, Eq) instance Agent Bug where agentId (Bug s) = s liveALittle bug = return bug -- stub -- -- And now my users only have to write stuff like... -- u :: SimpleUniverse u = SimpleUniverse "mydir"

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  • can a .class file be added to the urlpath of a URLClassLoader

    - by java_geek
    I have a custom class loader which extends from a URLClassLoader. I added a .class file to the urlpath using addURL(); but when i do a class.forname() using this loader i get a ClassNotFoundException. However, if i create a jar and add the jar to the urlpath, i do not get any exception. What can be added to the urlpath of a URLClassLoader usign addURL()

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  • Instanciate a class with a given id in ExtJS

    - by Miller
    Hello, I would like to know if it is possible to instanciate a class by its id . For example we have a class extending Ext.grid.GridPanel with an id property, is it possible to instanciate the class just knowing his id (which is the component id in this case) ?

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