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• Can I create a custom class that inherits from a strongly typed DataRow?

  - by Calvin Fisher

  I'm working on a huge, old project with a lot of brittle code, some of which has been around since the .NET 1.0 era, and it has been and will be worked on by other people... so I'd like to change as little as possible. I have one project in my solution that contains DataSet.xsd. This project compiles to a separate assembly (Data.dll). The database schema includes several tables arranged more or less hierarchically, but the only way the tables are actually linked together is through joins. I can get, e.g. DepartmentRow and EmployeeRow objects from the autogenerated code. EmployeeRow contains information from the employee's corresponding DepartmentRow through a join. I'm making a new report to view multiple departments and all their employees. If I use the existing data access scheme, all I will be able to get is a spreadsheet-like output where each employee is represented on one line, with department information repeated over and over in its appropriate columns. E.g.: Department1...Employee1... Department1...Employee2... Department2...Employee3... But what the customer would like is to have each department render like a heading, with a list of employees beneath each. E.g.: - Department1... Employee1... Employee2... + Department2... I'm trying to do this by inheriting hierarchical objects from the autogenerated Row objects. E.g.: public class Department : DataSet.DepartmentRow { public List<Employee> Employees; } That way I could nest the data in the report by using a collection of Department objects as the DataSource, each of which will put its list of Employees in a subreport. The problem is that this gives me a The type Data.DataSet.DepartmentRow has no constructors defined error. And when I try to make a constructor, e.g. public class Department : DataSet.DepartmentRow { private Department() { } public List<Employee> Employees; } I get a 'Data.DataSet.DepartmentRow(System.Data.DataRowBuilder)' is inaccessible due to its protection level. error in addition to the first one. Is there a way to accomplish what I'm trying to do? Or is there something else I should be trying entirely?

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• In C#, can I hide/modify accessors in subclasses?

  - by Diego

  I'm not even sure what this principle is called or how to search for it, so I sincerely apologize if it has been brought up before, but the best way to do it is with an example. class Properties { public string Name { get; set; } } class MyClass { class SubProperties: Properties { public override Name { get { return GetActualName(); } set { _value = SetActualName(value); } } } public SubProperties ClassProperties; private GetActualName() { ClassProperties.Name = "name"; } private SetActualName(string s) { ClassProperties.Name = SomeOtherFunction(s); } } The idea is to have any object that instantiates MyClass have a fully accessible property ClassProperties. To that object, it would look exactly like a Properties object, but behind the scenes, MyClass is actually computing and modifying the results of the fields. This method of declaration is obviously wrong since I can't access GetActualName() and SetActualName() from within the SubProperties definition. How would I achieve something like this?

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• How can you extend the Bitmap class

  - by vrish88

  Hello, I am trying to extend the Bitmap class so that I can apply my own effects to an image. When I use this code: namespace ImageEditor { public class Effects : System.Drawing.Bitmap { public void toBlackAndWhite() { System.Drawing.Bitmap image = (Bitmap)this; AForge.Imaging.Filters.Grayscale filter = new AForge.Imaging.Filters.Grayscale(); this = filter.Apply(this); } } } I get the following error: 'ImageEditor.Effects': cannot derive from sealed type 'System.Drawing.Bitmap' So is there a way to get around this or is it simply not possible to extend the class? Thanks.

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• How to inherit events between objects

  - by marduck19

  I need inherit events and properties for example move a picture around the form Y have this code to move the picture but y need create multiple images with the same behavior private void pictureBox_MouseDown(object sender, MouseEventArgs e) { if (e.Button == MouseButtons.Left) { x = e.X; y = e.Y; } } private void pictureBox_MouseMove(object sender, MouseEventArgs e) { if (e.Button == MouseButtons.Left) { pictureBox.Left += (e.X -x); pictureBox.Top += (e.Y - y); } }

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• Method interception in PHP 5.*

  - by Rolf

  Hi everybody, I'm implementing a Log system for PHP, and I'm a bit stuck. All the configuration is defined in an XML file, that declares every method to be logged. XML is well parsed and converted into a multidimensionnal array (classname = array of methods). So far, so good. Let's take a simple example: #A.php class A { public function foo($bar) { echo ' // Hello there !'; } public function bar($foo) { echo " $ù$ùmezf$z !"; } } #B.php class B { public function far($boo) { echo $boo; } } Now, let's say I've this configuration file: <interceptor> <methods class="__CLASS_DIR__A.php"> <method name="foo"> <log-level>INFO</log-level> <log-message>Transaction init</log-message> </method> </methods> <methods class="__CLASS_DIR__B.php"> <method name="far"> <log-level>DEBUG</log-level> <log-message>Useless</log-message> </method> </methods> </interceptor> The thing I'd like AT RUNTIME ONLY (once the XML parser has done his job) is: #Logger.php (its definitely NOT a final version) -- generated by the XML parser class Logger { public function __call($name,$args) { $log_level = args[0]; $args = array_slice($args,1); switch($method_name) { case 'foo': case 'far': //case ..... //write in log files break; } //THEN, RELAY THE CALL TO THE INITIAL METHOD } } #"dynamic" A.php class A extends Logger { public function foo($log_level, $bar) { echo ' // Hello there !'; } public function bar($foo) { echo " $ù$ùmezf$z !"; } } #"dynamic" B.php class B extends Logger { public function far($log_level, $boo) { echo $boo; } } The big challenge here is to transform A and B into their "dynamic" versions, once the XML parser has completed its job. The ideal would be to achieve that without modifying the code of A and B at all (I mean, in the files) - or at least find a way to come back to their original versions once the program is finished. To be clear, I wanna find the most proper way to intercept method calls in PHP. What are your ideas about it ??? Thanks in advance, Rolf

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• How to find the first declaring method for a reference method

  - by Oliver Gierke

  Suppose you have a generic interface and an implementation: public interface MyInterface<T> { void foo(T param); } public class MyImplementation<T> implements MyInterface<T> { void foo(T param) { } } These two types are frework types. In the next step I want allow users to extend that interface as well as redeclare foo(T param) to maybe equip it with further annotations. public interface MyExtendedInterface extends MyInterface<Bar> { @Override void foo(Bar param); // Further declared methods } I create an AOP proxy for the extended interface and intercept especially the calls to furtherly declared methods. As foo(…) is no redeclared in MyExtendedInterface I cannot execute it by simply invoking MethodInvocation.proceed() as the instance of MyImplementation only implements MyInterface.foo(…) and not MyExtendedInterface.foo(…). So is there a way to get access to the method that declared a method initially? Regarding this example is there a way to find out that foo(Bar param) was declared in MyInterface originally and get access to the accoriding Method instance? I already tried to scan base class methods to match by name and parameter types but that doesn't work out as generics pop in and MyImplementation.getMethod("foo", Bar.class) obviously throws a NoSuchMethodException. I already know that MyExtendedInterface types MyInterface to Bar. So If I could create some kind of "typed view" on MyImplementation my math algorithm could work out actually.

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• c# inheriting generic collection and serialization...

  - by Stecy

  Hi, The setup: class Item { private int _value; public Item() { _value = 0; } public int Value { get { return _value; } set { _value = value; } } } class ItemCollection : Collection<Item> { private string _name; public ItemCollection() { _name = string.Empty; } public string Name { get {return _name;} set {_name = value;} } } Now, trying to serialize using the following code fragment: ItemCollection items = new ItemCollection(); ... XmlSerializer serializer = new XmlSerializer(typeof(ItemCollection)); using (FileStream f = File.Create(fileName)) serializer.Serialize(f, items); Upon looking at the resulting XML I see that the ItemCollection.Name value is not there! I think what may be happening is that the serializer sees the ItemCollection type as a simple Collection thus ignoring any other added properties... Is there anyone having encountered such a problem and found a solution? Regards, Stécy

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• Use super class's address/pointer in initialization list

  - by JQ

  context 1: class D : public B1, public B2{}; context 2: B2 takes B1 to initialize: B2( B1 * ) //B2's constructor my question is in D's initialization list: D::D() : B1(), B2( ? )... What should be in ? I don't want to put " (B1*)this " in the ? place, because it's no good to use "this" in initialization list. And since B1 part has been initialized, it makes sense to use it. What should I do ?

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• nhibernate virtual methods & resharper

  - by Berryl

  I am curious how other Resharper users deal wih R#'s complaint about virtual methods it thinks are unused because it can't tell that NHIb will use them at runtime. I currently leave it as a hint, reluctantly, although am tempted to shut it off completely. Cheers, Berryl

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• How do you configure IIS5 advanced settings from command line?

  - by Jason

  I am trying to automate some of the build process for my asp.net apps by creating the virtual directories it needs and setting all their settings in a batch file. So far I have been able to figure out how to create virtual directories, but how to do you configure them beyond that? For example I need to be able to set them as an application, set the default document, change framework version, turn on integrated authentication, etc. Does anyone know of any scripts that can do all this without a third party utility? Does the adsutil.vbs admin script do any of this?

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• Windows Mobile Development on MacBook Pro?

  - by Ted Nichols

  I am a frequent Windows Mobile application developer in need of a new development laptop. I am considering a MacBook or Macbook Pro running either Fusion from VMWare or Parallels Desktop. This will give me the option to port my applications to the iPhone depending on what MS does with WM 6.5 and 7. Has anybody tried doing Windows Mobile development using Microsoft Windows Mobile Device Center (or ActiveSync) and VS2008 on the MacBook Pro using one of these virtual machines? Does the device emulator work properly? What about debugging a Windows Mobile device over a USB cable? In general, do most USB drivers (non HID) designed for Windows work under these virtual machines? Thanks.

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• Sharing view logic in Django

  - by Jeremy B.

  I've begun diving into Django again and I'm having trouble finding the parallel to some common concepts from my life in C#. While using .NET MVC I very often find myself creating a base controller which will provide a base action implementation to take care of the type of stuff I want to do on every request, like retrieving user information, getting localization values. Where I'm finding myself confused is how to do this in Django. I am getting more familiar with the MVT concept but I can't seem to find how to solve this scenario. I've looked at class based views and the generic views yet they didn't seem to work how I expected. What am I missing? How can i create default logic that each view will be instructed to run but not have to write it in each view method?

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• Is there any way to manipulate variables passed in to a child class constructor before passing it of

  - by Matt

  Hi, Is there any way to delay calling a superclass constructor so you can manipulate the variables first? Eg. public class ParentClass { private int someVar; public ParentClass(int someVar) { this.someVar = someVar; } } public class ChildClass : ParentClass { public ChildClass(int someVar) : base(someVar) { someVar = someVar + 1 } } I want to be able to send the new value for someVar (someVar + 1) to the base class constructor rather than the one passed in to the ChildClass constructor. Is there any way to do this? Thanks, Matt

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• Me As Child Type

  - by Steven

  I have a MustInherit Parent class with two Child classes which Inherit from the Parent. How can I use (or Cast) Me in a Parent function as the the child type of that instance? EDIT: My actual goal is to be able to serialize (BinaryFormatter.Serialize(Stream, Object)) either of my child classes. However, "repeating the code" in each child "seems" wrong.

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• Two models, one STI and a Validation

  - by keruilin

  Let's say I have two tables -- Products and Orders. For the sake of simplicity assume that only one product can be purchased at a time so there is no join table like order_items. So the relationship is that Product has many orders, and Order belongs to product. Therefore, product_id is a fk in the Order table. The product table is STI -- with the subclasses being A, B, C. When the user orders subclass Product C, two special validations must be checked on the Order model fields order_details and order_status. These two fields can be nil for all other Product subclasses (ie A and B). In other words, no validation needs to run for these two fields when a user purchases A and B. My question is: How do I write validations (perhaps custom?) in the Order model so that the Order model knows to only run the validations for the two fields -- order_details and order_status -- when Product subclass C is being saved to the orders table?

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• spring - constructor injection and overriding parent definition of nested bean

  - by mdma

  I've read the Spring 3 reference on inheriting bean definitions, but I'm confused about what is possible and not possible. For example, a bean that takes a collaborator bean, configured with the value 12 <bean name="beanService12" class="SomeSevice"> <constructor-arg index="0"> <bean name="beanBaseNested" class="SomeCollaborator"> <constructor-arg index="0" value="12"/> </bean> </constructor-arg> </bean> I'd then like to be able to create similar beans, with slightly different configured collaborators. Can I do something like <bean name="beanService13" parent="beanService12"> <constructor-arg index="0"> <bean> <constructor-arg index="0" value="13"/> </bean> </constructor> </bean> I'm not sure this is possible and, if it were, it feels a bit clunky. Is there a nicer way to override small parts of a large nested bean definition? It seems the child bean has to know quite a lot about the parent, e.g. constructor index. I'd prefer not to change the structure - the parent beans use collaborators to perform their function, but I can add properties and use property injection if that helps. This is a repeated pattern, would creating a custom schema help? Thanks for any advice!

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• Define interface for loading custom UserControls through reflection

  - by Tim

  I'm loading custom user controls into my form using reflection. I would like all my user controls to have a "Start" and "End" method so they should all be like: public interface IStartEnd { void Start(); void End(); } public class AnotherControl : UserControl, IStartEnd { public void Start() { } public void End() { } } I would like an interface to load through reflection, but the following obviously wont work as an interface cannot inherit a class: public interface IMyUserControls : UserControl, IInit, IDispose { }

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• .NET C# Explicit implementation of grandparent's interface method in the parent interface

  - by Cristi Diaconescu

  That title's a mouthful, isn't it?... Here's what I'm trying to do: public interface IBar { void Bar(); } public interface IFoo: IBar { void Foo(); } public class FooImpl: IFoo { void IFoo.Foo() { /*works as expected*/ } //void IFoo.Bar() { /*i'd like to do this, but it doesn't compile*/ } void IBar.Bar() { /*works as expected*/ } } So... Is there a way to declare IFoo.Bar(){...} in my class, other than basically merging the two interfaces into one? And, if not, why?

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• Is it possible to add JPA annotation to superclass instance variables?

  - by Kristofer Borgstrom

  Hi, I am creating entities that are the same for two different tables. In order do table mappings etc. different for the two entities but only have the rest of the code in one place - an abstract superclass. The best thing would be to be able to annotate generic stuff such as column names (since the will be identical) in the super class but that does not work because JPA annotations are not inherited by child classes. Here is an example: public abstract class MyAbstractEntity { @Column(name="PROPERTY") //This will not be inherited and is therefore useless here protected String property; public String getProperty() { return this.property; } //setters, hashCode, equals etc. methods } Which I would like to inherit and only specify the child-specific stuff, like annotations: @Entity @Table(name="MY_ENTITY_TABLE") public class MyEntity extends MyAbstractEntity { //This will not work since this field does not override the super class field, thus the setters and getters break. @Column(name="PROPERTY") protected String property; } Any ideas or will I have to create fields, getters and setters in the child classes? Thanks, Kris

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• Virgin STI Help

  - by Mutuelinvestor

  I am working on a horse racing application and I'm trying to utilize STI to model a horse's connections. A horse's connections is comprised of his owner, trainer and jockey. Over time, connections can change for a variety of reasons: The horse is sold to another owner The owner switches trainers or jockey The horse is claimed by a new owner As it stands now, I have model this with the following tables: horses connections (join table) stakeholders (stakeholder has three sub classes: jockey, trainer & owner) Here are my clases and associations: class Horse < ActiveRecord::Base has_one :connection has_one :owner_stakeholder, :through => :connection has_one :jockey_stakeholder, :through => :connection has_one :trainer_stakeholder, :through => :connection end class Connection < ActiveRecord::Base belongs_to :horse belongs_to :owner_stakeholder belongs_to :jockey_stakeholder belongs_to :trainer_stakeholder end class Stakeholder < ActiveRecord::Base has_many :connections has_many :horses, :through => :connections end class Owner < Stakeholder # Owner specific code goes here. end class Jockey < Stakeholder # Jockey specific code goes here. end class Trainer < Stakeholder # Trainer specific code goes here. end One the database end, I have inserted a Type column in the connections table. Have I modeled this correctly. Is there a better/more elegant approach. Thanks in advance for you feedback. Jim

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• Inherit static properties in subclass without redeclaration?

  - by David

  Hi, I'm having the same problem as this guy with the application I'm writing right now. The problem is that static properties are not being inherited in subclasses, and so if I use the static:: keyword in my main class, it sets the variable in my main class as well. It works if I redeclare the static variables in my subclass, but I expect to have a large number of static properties and subclasses and wish to avoid code duplication. The top-rated response on the page I linked has a link to a few "workarounds", but it seems to have 404'd. Can anyone lend me some help or perhaps point me in the direction of said workarounds?

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• Android virtual keyboard turn on kaps lock

  - by Faisal khan

  I have an edit text field. When the user clicks on it by default it shows small letters on the virtual keyboard. I want by default to display first letter caps and rest of them small on the keyboard. How can this be done?

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• How to inherit constructors with arguments in .NET?

  - by Soumya92

  I have a "MustInherit" .NET class which declares a constructor with an integer parameter. However, Visual Studio gives me an error when I create any derived class stating that there is no constructor that can be called without any arguments. Is it possible to inherit the constructor with arguments? Right now, I have to use Public Sub New(ByVal A As Integer) MyBase.New(A) End Sub in the derived classes. Is there any way to avoid this?

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• When do instance variables get initialized and values assigned?

  - by AKh

  When doees the instance variable get initialized? Is it after the constructor block is done or before it? Consider this example: public abstract class Parent { public Parent(){ System.out.println("Parent Constructor"); init(); } public void init(){ System.out.println("parent Init()"); } } public class Child extends Parent { private Integer attribute1; private Integer attribute2 = null; public Child(){ super(); System.out.println("Child Constructor"); } public void init(){ System.out.println("Child init()"); super.init(); attribute1 = new Integer(100); attribute2 = new Integer(200); } public void print(){ System.out.println("attribute 1 : " +attribute1); System.out.println("attribute 2 : " +attribute2); } } public class Tester { public static void main(String[] args) { Parent c = new Child(); ((Child)c).print(); } } OUTPUT: Parent Constructor Child init() parent Init() Child Constructor attribute 1 : 100 attribute 2 : null When the memory for the atribute 1 & 2 are allocated in the heap ? Curious to know why is attribute 2 is NULL ? Are there any design flaws?

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• method __getattr__ is not inherited from parent class

  - by ??????

  Trying to subclass mechanize.Browser class: from mechanize import Browser class LLManager(Browser, object): IS_AUTHORIZED = False def __init__(self, login = "", passw = "", *args, **kwargs): super(LLManager, self).__init__(*args, **kwargs) self.set_handle_robots(False) But when I make something like this: lm["Widget[LinksList]_link_1_title"] = anc then I get an error: Traceback (most recent call last): File "<pyshell#8>", line 1, in <module> lm["Widget[LinksList]_link_1_title"] = anc TypeError: 'LLManager' object does not support item assignment Browser class have overridden method __getattr__ as shown: def __getattr__(self, name): # pass through _form.HTMLForm methods and attributes form = self.__dict__.get("form") if form is None: raise AttributeError( "%s instance has no attribute %s (perhaps you forgot to " ".select_form()?)" % (self.__class__, name)) return getattr(form, name) Why my class or instance don't get this method as in parent class?

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