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  • Access class instance "name" dynamically in Python

    - by user328317
    In plain english: I am creating class instances dynamically in a for loop, the class then defines a few attributes for the instance. I need to later be able to look up those values in another for loop. Sample code: class A: def init(self, name, attr): self.name=name self.attr=attr names=("a1", "a2", "a3") x=10 for name in names: name=A(name, x) x += 1 ... ... ... for name in names: print name.attr How can I create an identifier for these instances so they can be accessed later on by "name"? I've figured a way to get this by associating "name" with the memory location: class A: instances=[] names=[] def init(self, name, attr): self.name=name self.attr=attr A.instances.append(self) A.names.append(name) names=("a1", "a2", "a3") x=10 for name in names: name=A(name, x) x += 1 ... ... ... for name in names: index=A.names.index(name) print "name: " + name print "att: " + str(A.instances[index].att) This has had me scouring the web for 2 days now, and I have not been able to find an answer. Maybe I don't know how to ask the question properly, or maybe it can't be done (as many other posts seemed to be suggesting). Now this 2nd example works, and for now I will use it. I'm just thinking there has to be an easier way than creating your own makeshift dictionary of index numbers and I'm hoping I didn't waste 2 days looking for an answer that doesn't exist. Anyone have anything? Thanks in advance, Andy Update: A coworker just showed me what he thinks is the simplest way and that is to make an actual dictionary of class instances using the instance "name" as the key.

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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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  • Suggestions: Anti-Pattern counter-examples

    - by Tom W
    It doesn't seem that this exact question has been asked before, so I'll fire away: Most of us are familiar with the concept of an anti-pattern. However, avoiding implementation of anti-patterns can in principle swing too far the other way and cause problems itself. As an example, "Design by Committee" has a counter-example that I'd call "Design by Maverick" - wherein the design of an important feature is handed off to an individual to do what they think best, with the intention of reviewing their work later and deciding whether it should be finalised or go through another iteration. This takes much longer in practice as the rest of the team are occupied by other things, and can end up with a feature that's useful to nobody, particularly if the Maverick is not themselves an experienced end-user. Does anyone have any more examples of anti-pattern counter-examples?

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  • I Clean Solution'd my Winform App and now it's broken...

    - by Refracted Paladin
    I have a Winform App that uses a 3rd Party Library of Controls, DevExpress. I also created a bunch of Controls myself, extending those controls. Everything has been working fine when all of a sudden I opened VS today and on the Design Page all my extended controls were missing. I then tried rebuilding to no avail. Then I tried Cleaning and Rebuilding and made it even worse. Now I have tons(520) of erros stating things like -- Error 179 The name 'datBirthDate' does not exist in the current context D:\Documents\Visual Studio 2008\Projects\MatrixReloaded\MatrixReloaded\Controls\Member\ucGeneral.cs 339 17 MatrixReloaded also if I try to open a form or user control in Design Mode I first get this -- could not find type, "MyType" please make sure that the assembly that contains this type is referenced and then, if I click Ignore and Continue I get this for all Forms and Contros when I try and look at them in Design Mode -- Exception of type System.OutOfMemoryException was thrown Help!?!? When I googled I came across mostly references to VS 2003...I am on 2008 sp1.

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  • Accessing main class stage event listener.

    - by Hwang
    I wanted to remove an event listener from main class stage, but i get the error 1120: Access of undefined property stage. How do I actually access the stage? custom class: import main; main.disableVcam(); main class: public static function disableVcam():void { trace("disable"); stage.removeEventListener(MouseEvent.MOUSE_MOVE, movevC); }

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  • Create generic class instance throws TypeLoadException

    - by Elisa
    My TestLayer class has the namespace: "BLL.Infrastructure.TestLayer" and is inside the assembly: "BLL" public class LayerFactory<T, U> { public static IBaseLayer<T, U> Get() { var obj = Activator.CreateInstance("BLL", "BLL.Infrastructure.TestLayer", new object[] { (IBaseLayer<T, U>)null }); } } When I run the code the Activator throws an TypeLoadException with no more details Thats the concrete class it should create: GenericBaseLayer implements the IBaseLayer. public class TestLayer<T, U> : GenericBaseLayer<MyRequest, MyInfo.ActionType> { public TestLayer(IBaseLayer<MyRequest, MyInfo.ActionType> layer) : base(layer) { } } What do I wrong?

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  • Error in my OO Generics design. How do I workaround it?

    - by John
    I get "E2511 Type parameter 'T' must be a class type" on the third class. type TSomeClass=class end; ParentParentClass<T>=class end; ParentClass<T: class> = class(ParentParentClass<T>) end; ChildClass<T: TSomeClass> = class(ParentClass<T>) end; I'm trying to write a lite Generic Array wrapper for any data type(ParentParentClass) ,but because I'm unable to free type idenitifiers( if T is TObject then Tobject(T).Free) , I created the second class, which is useful for class types, so I can free the objects. The third class is where I use my wrapper, but the compiler throws that error. How do I make it compile?

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  • Any solution or programming tips for Inner class?

    - by huahsin68
    Hi, I'm having some toubt here. Hope you guys can share out some programming tips. Just curious to know whether is it a good programming practice if I do something like the code below. class Outer { public: class Inner { public: Inner() {} } Outer() {} }; I have been doing this for structure where I only want my structure to be expose to my class instead of global. But the case is different here, I am using a class now? Have you guys facing such a situation before? Very much appreciated on any advice from you ;)

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  • C++ explicit template specialization of templated constructor of templated class

    - by Victor Liu
    I have a class like template <class T> struct A{ template <class U> A(U u); }; I would like to write an explicit specialization of this for a declaration like A<int>::A(float); In the following test code, if I comment out the specialization, it compiles with g++. Otherwise, it says I have the wrong number of template parameters: #include <iostream> template <class T> struct A{ template <class U> A(T t, U *u){ *u += U(t); } }; template <> template <> A<int>::A<int,float>(int t, float *u){ *u += U(2*t); } int main(){ float f = 0; int i = 1; A<int>(i, &f); std::cout << f << std::endl; return 0; }

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  • creative way for implementing Data object with it's corespanding buisness logic class in java

    - by ekeren
    I have a class that need to be serialized (for both persistentcy and client-server communication) for simplicity reasons lets 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 loose my hierarchy freedom, does any of you have any creative solution for this problem... I also reviewed DAO pattern: http://java.sun.com/blueprints/patterns/DAO.html

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  • PHP 'instanceof' failing with class constant

    - by Nathan Loding
    I'm working on a framework that I'm trying to type as strongly as I possibly can. (I'm working within PHP and taking some of the ideas that I like from C# and trying to utilize them within this framework.) I'm creating a Collection class that is a collection of domain entities/objects. It's kinda modeled after the List<T> object in .Net. I've run into an obstacle that is preventing me from typing this class. If I have a UserCollection, it should only allow User objects into it. If I have a PostCollection, it should only allow Post objects. All Collections in this framework need to have certain basic functions, such as add, remove, iterate. I created an interface, but found that I couldn't do the following: interface ICollection { public function add($obj) } class PostCollection implements ICollection { public function add(Post $obj) {} } This broke it's compliance with the interface. But I can't have the interface strongly typed because then all Collections are of the same type. So I attempted the following: interface ICollection { public function add($obj) } abstract class Collection implements ICollection { const type = 'null'; } class PostCollection { const type = 'Post'; public function add($obj) { if(!($obj instanceof self::type)) { throw new UhOhException(); } } } When I attempt to run this code, I get syntax error, unexpected T_STRING, expecting T_VARIABLE or '$' on the instanceof statement. A little research into the issue and it looks like the root of the cause is that $obj instanceof self is valid to test against the class. It appears that PHP doesn't process the entire self::type constant statement in the expression. Adding parentheses around the self::type variable threw an error regarding an unexpected '('. An obvious workaround is to not make the type variable a constant. The expression $obj instanceof $this->type works just fine (if $type is declared as a variable, of course). I'm hoping that there's a way to avoid that, as I'd like to define the value as a constant to avoid any possible change in the variable later. Any thoughts on how I can achieve this, or have I take PHP to it's limit in this regard? Is there a way of "escaping" or encapsulating self::this so that PHP won't die when processing it?

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  • Java: is Exception class thread-safe?

    - by Vilius Normantas
    As I understand, Java's Exception class is certainly not immutable (methods like initCause and setStackTrace give some clues about that). So is it at least thread-safe? Suppose one of my classes has a field like this: private final Exception myException; Can I safely expose this field to multiple threads? I'm not willing to discuss concrete cases where and why this situation could occur. My question is more about the principle: can I tell that a class which exposes field of Exception type is thread-safe? Another example: class CustomException extends Exception { ... } Is this class thread-safe?

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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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  • 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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  • book with good examples for each implementation?

    - by ajsie
    i've read about design patterns and it seems that there are a lot of different design patterns to use. i wonder if there are some books that acts like a reference. "you want to build a framework, then consider this, this and this pattern". also giving some examples. then jumps to another implementation eg. search engine and gives some patterns and concrete examples to use. in this way you learn about the weakness and strength about each pattern and where they will fit, instead of just reading about every design pattern decoupled from each other. are there good "reference sheets" or other tutorials good for a beginner at this? 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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  • How to remove class Conditionally ?

    - by Wazdesign
    $("li").hoverIntent({ sensitivity: 3, interval: 200, over: addOver, timeout: 500, out: removeOver }); function addOver(){ $(this).addClass('over').children('a:first').addClass('active');} function removeOver(){ $(this).removeClass('over').children('a:first').removeClass('active');} alert ('version 2 menu'); }); On mouseout I want to remove class of " li a" if it already dont have class. I want to remove the class of the children.

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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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  • friend declaration block an external function access to the private section of a class

    - by MiP
    I'm trying to force function caller from a specific class. For example this code bellow demonstrate my problem. I want to make 'use' function would be called only from class A. I'm using a global namespace all over the project. a.h #include "b.h" namespace GLOBAL{ class A{ public: void doSomething(B); } } a.cpp #include "a.h" using namespace GLOBAL; void A::doSomething(B b){ b.use(); } b.h namespace GLOBAL{ class B{ public: friend void GLOBAL::A::doSomething(B); private: void use(); } Compiler says: ‘GLOBAL::A’ has not been declared ‘void GLOBAL::B::use()’ is private Can anyone help here ? Thanks a lot, Mike.

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  • PDO using singleton stored as class properity

    - by Misiur
    Hi again. OOP drives me crazy. I can't move PDO to work. Here's my DB class: class DB extends PDO { public function &instance($dsn, $username = null, $password = null, $driver_options = array()) { static $instance = null; if($instance === null) { try { $instance = new self($dsn, $username, $password, $driver_options); } catch(PDOException $e) { throw new DBException($e->getMessage()); } } return $instance; } } It's okay when i do something like this: try { $db = new DB(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(DBException $e) { echo $e->getMessage(); } But this: try { $db = DB::instance(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(DBException $e) { echo $e->getMessage(); } Does nothing. I mean, even when I use wrong password/username, I don't get any exception. Second thing - I have class which is "heart" of my site: class Core { static private $instance; public $db; public function __construct() { if(!self::$instance) { $this->db = DB::instance(DB_TYPE.':hpost='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } return self::$instance; } private function __clone() { } } I've tried to use "new DB" inside class, but this: $r = $core->db->query("SELECT * FROM me_config"); print_r($r->fetch()); Return nothing. $sql = "SELECT * FROM me_config"; print_r($core->db->query($sql)); I get: PDOStatement Object ( [queryString] => SELECT * FROM me_config ) I'm really confused, what am I doing wrong?

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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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  • Python: Is there a way to reflectivly list all attributes of a class

    - by hhafez
    Given a class such as def MyClass text = "hello" number = 123 Is there a way in python to inspect MyClass an determine that it has the two attributes text and number. I can not use something like inspect.getSource(object) because the class I am to get it's attributes for are generate using SWIG (so they are hidden in .so :) ). So I am really looking for something equivalant to Java's [Class.getDeclardFields][1] Any help would be appreciated, otherwise I'll have to solve this problem with SWIG + JAVA instead of SWIG + Python.

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  • executing a class in remote jvm

    - by redzedi
    Hi All, I have a small test class that i want to run on a particular jvm that's already up and running (basically it's an web application running on Tomcat) . The reason i want to do this is i want to execute a small test class (with the main method and all) within that jvm so that i get the same environment (loaded and initialized classes) for my test class. Is it possible to indicate that ,say through a jvm parameter, that it should not initialize a new vm to execute my class but instead go and execute on the remote vm and show me the result here, on my console. So the local jvm acts as a kind of thin proxy ? I am not aware in case there are some tools that should make this possible ... also heard somewhere that java 6 jvm comes with an option like this , is that true ?? Please help me. Thanks,

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