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  • WPF inherited UserControl lost VS designer support

    - by PaN1C_Showt1Me
    Hi ! I' written this UserControl: <my:MyUserControl x:Class="MyClass" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:my="clr-namespace:MyNameSpace.MyControls;assembly=MyAssembly"> </my:MyUserControl> public partial class Editor : MyNameSpace.MyControls.MyUserControl {} Everything works, the control is shown in the VS 2008 Designer, but I cannot click directly in the elements and select them as it was with UserControl. Any idea how to solve it?

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  • Are static members inherited? (C++)

    - by Keand64
    When static members are inherited, are they static for the entire heirarchy, or just that class, ie: class SomeClass { public: SomeClass(){total++;} static int total; }; class SomeDerivedClass: public SomeClass { public: SomeDerivedClass(){total++;} }; int main() { SomeClass A; SomeClass B; SomeDerivedClass C; return 0; } would total be 3 in all three instances, or would it be 2 for SomeClass and 1 for SomeDerivedClass?

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  • Can I make a derived class inherit a derived member from its base class in Java?

    - by Eric
    I have code that looks like this: public class A { public void doStuff() { System.out.print("Stuff successfully done"); } } public class B extends A { public void doStuff() { System.out.print("Stuff successfully done, but in a different way"); } public void doMoreStuff() { System.out.print("More advanced stuff successully done"); } } public class AWrapper { public A member; public AWrapper(A member) { this.member = member; } public void doStuffWithMember() { a.doStuff(); } } public class BWrapper extends AWrapper { public B member; public BWrapper(B member) { super(member); //Pointer to member stored in two places: this.member = member; //Not great if one changes, but the other does not } public void doStuffWithMember() { member.doMoreStuff(); } } However, there is a problem with this code. I'm storing a reference to the member in two places, but if one changes and the other does not, there could be trouble. I know that in Java, an inherited method can narrow down its return type (and perhaps arguments, but I'm not certain) to a derived class. Is the same true of fields?

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  • Root base class in C++

    - by Littlesmith
    Every object in .NET inherits (directly or indirectly) from the common root base "Object". Is there such a common object root in C++? How do I pass any object to a function? public void DoSomeStuff(object o) { ... }

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  • unable to pas derived List<>

    - by Tarscher
    Hi all, I have class A {} class B : A {} I also have a method that expects a List parameter void AMethod(List<A> parameter) {} Why can't I List<B> bs = new List<B>(); AMethod(bs); And secondly what is the most elegant way to make this work? regards

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  • Determine an object's class returned by a factory method (Error: function does not take 1 arguments

    - by tzippy
    I have a factorymethod that either returns an object of baseclass or one that is of derivedclass (a derived class of baseclass). The derived class has a method virtual void foo(int x) that takes one argument. baseclass however has virtual void foo() without an argument. In my code, a factory method returns a pointer of type bar that definetly points to an object of class derivedclass. However since this is only known at runtime I get a compiler error saying that foo() does not take an argument. Can I cast this pointer to a pointer of type derivedclass? std::auto_ptr<baseclass> bar = classfactory::CreateBar(); //returns object of class derivedclass bar->foo(5); class baseclass { public: virtual void foo(); } class derivedclass : public baseclass { public: virtual void foo(int x); }

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  • Should I share UI for objects that use common fields?

    - by wb
    I have a parent class that holds all of the fields that are common between all device types. From that, I have a few derived classes that each hold their unique fields. Say I have device type "Switch" and "Transformer". Both derived classes only have 2-3 of their own unique fields. When doing the UI design (windows forms) in this case. Should I create two separate forms for each device type or create a user control with all fields that are shared among all devices? Thank you.

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  • Calling child constructor by casting (ChildClass)parentObject; to track revisions

    - by FreshCode
    To track revisions of a Page class, I have a PageRevision class which inherits from Page and adds a revision ID (Guid RevisionID;). If possible, how should I cast an existing Page object to a PageRevision and ensure that the PageRevision constructor is called to create a new revision ID? I could could have a PageRevision(Page page) constructor which generates the Guid and copies all the Page attributes, but I want to automate it, especially if a Page class has many attributes (and I later add one, and forget to modify the copy constructor). Desired use Page page = new Page(123, "Page Title", "Page Body"); // where 123 is page ID PageRevision revision = (PageRevision)page; // now revision.RevisionID should be a new Guid. Page, PageRevision classes: public class Page { public int ID { get; set; } public string Title { get; set; } public string Body { get; set; } } public class PageRevision : Page { public Guid RevisionID { get; set; } public PageRevision() { this.RevisionID = Guid.NewGuid(); } }

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  • PHP class extends not working why and is this how to correctly extend a class?

    - by Matthew
    Hi so I'm trying to understand how inherteince works in PHP using object oriented programming. The main class is Computer, the class that is inheriting is Mouse. I'm extedning the Computer class with the mouse class. I use __construct in each class, when I istinate the class I use the pc type first and if it has mouse after. For some reason computer returns null? why is this? class Computer { protected $type = 'null'; public function __construct($type) { $this->type = $type; } public function computertype() { $this->type = strtoupper($this->type); return $this->type; } } class Mouse extends Computer { protected $hasmouse = 'null'; public function __construct($hasmouse){ $this->hasmouse = $hasmouse; } public function computermouse() { if($this->hasmouse == 'Y') { return 'This Computer has a mouse'; } } } $pc = new Computer('PC', 'Y'); echo $pc->computertype; echo $pc->computermouse;

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  • [PHP] How to unset object's inherited properties ?

    - by vbklv
    I have an Object ( [id] => 1 [parent_id] => 0 [result:Database:private] => [db:Database:private] => mysqli Object ( [affected_rows] => 0 ... ) ) Obviously, the Object has inherited the 'db' and 'result' properties of the parent Database class. unset($object-result) nor unset($object-result:Database) nor unset($object-result:Database:private) work. How could I unset those properties when they are no longer needed (i.e. when the object properties are about to be output)? Is it a generally a good idea to have a database object as an inherited property of other classes (extend one Database class with all other classes that use database connections)?

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  • Constructors from extended class in Java

    - by Crystal
    I'm having some trouble with a hw assignment. In one assignment, we had to create a Person class. Mine was: public class Person { String firstName; String lastName; String telephone; String email; public Person() { firstName = ""; lastName = ""; telephone = ""; email = ""; } public Person(String firstName) { this.firstName = firstName; } public Person(String firstName, String lastName, String telephone, String email) { this.firstName = firstName; this.lastName = lastName; this.telephone = telephone; this.email = email; } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getTelephone() { return telephone; } public void setTelephone(String telephone) { this.telephone = telephone; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public boolean equals(Object otherObject) { // a quick test to see if the objects are identical if (this == otherObject) { return true; } // must return false if the explicit parameter is null if (otherObject == null) { return false; } if (!(otherObject instanceof Person)) { return false; } Person other = (Person) otherObject; return firstName.equals(other.firstName) && lastName.equals(other.lastName) && telephone.equals(other.telephone) && email.equals(other.email); } public int hashCode() { return 7 * firstName.hashCode() + 11 * lastName.hashCode() + 13 * telephone.hashCode() + 15 * email.hashCode(); } public String toString() { return getClass().getName() + "[firstName = " + firstName + '\n' + "lastName = " + lastName + '\n' + "telephone = " + telephone + '\n' + "email = " + email + "]"; } } Now we have to extend that class and use that class in our constructor. The function protoype is: public CarLoan(Person client, double vehiclePrice, double downPayment, double salesTax, double interestRate, CAR_LOAN_TERMS length) I'm confused on how I use the Person constructor from the superclass. I cannot necessarily do super(client); in my constructor which is what the book did with some primitive types in their example. Not sure what the correct thing to do is... Any thoughts? Thanks!

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  • templated class : accessing derived normal-class methods

    - by user1019129
    I have something like this : class Container1 { public: method1() { ... } } class Container2 { public: method1() { ... } } template<class C = Container1> class X : public C { public: using C::method1(); ..... X(string& str) : C(str) {}; X& other_method() { method1(); ...; } } My question is why I have to use "using C::method1()", to be able to access the method.. Most of answers I found is for the case where templated-class inhering templated-class. Normally they mention using "this-", but this does not seem to work in this case. Can I do something else shorter... Also I'm suspecting the other error I'm getting is related to the same problem : no match call for (X<Container1>) (<std::string&>)

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  • How do I inherit abstract unit tests in Ruby?

    - by Graeme Moss
    I have two unit tests that should share a lot of common tests with slightly different setup methods. If I write something like class Abstract < Test::Unit::TestCase def setup @field = create end def test_1 ... end end class Concrete1 < Abstract def create SomeClass1.new end end class Concrete2 < Abstract def create SomeClass2.new end end then Concrete1 does not seem to inherit the tests from Abstract. Or at least I cannot get them to run in eclipse. If I choose "Run all TestCases" for the file that contains Concrete1 then Abstract is run even though I do not want it to be. If I specify Concrete1 then it does not run any tests at all! If I specify test_1 in Concrete1 then it complains it cannot find it ("uncaught throw :invalid_test (ArgumentError)"). I'm new to Ruby. What am I missing here?

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  • base pointer to derived class

    - by Jay
    Suppose there are Base class and Derived class. Base *A = new Base; Here A is a pointer point to Base class, and new constructs one that A points to. I also saw Base *B = new Derived; How to explain this? B is a pointer to Base Class, and a Derived class constructed and pointed by B? If there is a function derived from Base class, say, Virtual void f(), and it's been overridden in Derived class, then B->f() will invoke which version of the function? version in Base class, or version that overridden in Derived Class. What if there is a new function void g()in Derived, is B->g() going to invoke this function properly? One more is, is int *a = new double; or int *a = new int; legal?

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  • Javascript: Inherit method from base class and return the subclass's private variable

    - by marisbest2
    I have the following BaseClass defined: function BaseClass (arg1,arg2,arg3) { //constructor code here then - var privateVar = 7500; this.getPrivateVar = function() { return privateVar; }; } I want to have the following subclass which allows changing privateVar like so: function SubClass (arg1,arg2,arg3,privateVar) { //constructor code here then - var privateVar = privateVar; } SubClass.prototype = new BaseClass(); Now I want SubClass to inherit the getPrivateVar method. However, when I try this, it always returns 7500 which is the value in the BaseClass and not the value of privateVar. In other words, is it possible to inherit a BaseClass's public methods but have any references in them refer to the SubClass's properties? And how would I do that?

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  • Java : Using parent class method to access child class variable

    - by Jayant
    I have the following scenario : public class A { private int x = 5; public void print() { System.out.println(x); } } public class B extends A { private int x = 10; /*public void print() { System.out.println(x); }*/ public static void main(String[] args) { B b = new B(); b.print(); } } On executing the code, the output is : 5. How to access the child class(B's) variable(x) via the parent class method? Could this be done without overriding the print() method (i.e. uncommenting it in B)? [This is important because on overriding we will have to rewrite the whole code for the print() method again]

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  • Is there any difference these two pieces of code?

    - by Poiuyt
    #include<stdio.h> class A {public: int a; }; class B: public A {private: int a;}; int main(){ B b; printf("%d", b.a); return 0; } #include<stdio.h> class A {public: int a; }; class B: private A {}; int main(){ B b; printf("%d", b.a); return 0; } I ask because I get different errors: error: 'int B::a' is private error: 'int A::a' is inaccessible Apart from what the errors might reveal, is there any difference at all in the behaviour of these two pieces of code?

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  • Force the use of interface instead of concrete implementation in declaration (.NET)

    - by gammelgul
    In C++, you can do the following: class base_class { public: virtual void do_something() = 0; }; class derived_class : public base_class { private: virtual void do_something() { std::cout << "do_something() called"; } }; The derived_class overrides the method do_something() and makes it private. The effect is, that the only way to call this method is like this: base_class *object = new derived_class(); object->do_something(); If you declare the object as of type derived_class, you can't call the method because it's private: derived_class *object = new derived_class(); object->do_something(); // --> error C2248: '::derived_class::do_something' : cannot access private member declared in class '::derived_class' I think this is quite nice, because if you create an abstract class that is used as an interface, you can make sure that nobody accidentally declares a field as the concrete type, but always uses the interface class. Since in C# / .NET in general, you aren't allowed to narrow the access from public to private when overriding a method, is there a way to achieve a similar effect here?

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  • Similar Sub-Classes

    - by praks5432
    Lets say I have a class A that is fairly simple like this - public class A{ private int randomField = 0; protected int key; protected double dmg; } Now I want to write a number of sub-classes that inherit the protected fields and only differ based on the initial values that are assigned to those fields - for example, if I wrote two subclasses B and C, the only difference between those two sub-classes would be that the values key and dmg would have different values. They would share a method, set, which would be exactly the same, in that it would affect the same variable. I find when I'm writing these sub-classes I'm repeating myself, as I just change the constructor to set different initial values to key and dmg, and simply copy and paste the set method. Is there a 'good' way to do this?

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  • error - inherited class field undeclared according to g++

    - by infoholic_anonymous
    I have a code that has the following logic. g++ gives me the error that I have not declared n in my iterator2. What could be wrong? template <typename T> class List{ template <typename TT> class Node; Node<T> *head; /* (...) */ template <bool D> class iterator1{ protected: Node<T> n; public: iterator1( Node<T> *nn ) { n = nn } /* (...) */ }; template <bool D> class iterator2 : public iterator1<D>{ public: iterator2( Node<T> *nn ) : iterator1<D>( nn ) {} void fun( Node<T> *nn ) { n = nn; } /* (...) */ }; }; EDIT : I attach the actual header file. iterator1 would be iterable_frame and iterator2 - switchable_frame. #ifndef LST_H #define LST_H template <typename T> class List { public: template <typename TT> class Node; private: Node<T> *head; public: List() { head = new Node<T>; } ~List() { empty_list(); delete head; } List( const List &l ); inline bool is_empty() const { return head->next[0] == head; } void empty_list(); template <bool DIM> class iterable_frame { protected: Node<T> *head; Node<T> **caret; public: iterable_frame( const List &l ) { head = *(caret = &l.head); } iterable_frame( const iterable_frame &i ) { head = *(caret = i.caret); } ~iterable_frame() {} /* (...) - a few methods follow */ template <bool _DIM> friend class supervised_frame; }; template <bool DIM> class switchable_frame : public iterable_frame<DIM> { Node<T> *main_head; public: switchable_frame( const List& l ) : iterable_frame<DIM>(l) { main_head = head; } inline bool next_frame() { caret = &head->next[!DIM]; head = *caret; return head != main_head; } }; template <bool DIM> class supervised_frame { iterable_frame<DIM> sentinels; iterable_frame<DIM> cells; public: supervised_frame( const List &l ) : sentinels(l), cells(l) {} ~supervised_frame() {} /* (...) - a few methods follow */ }; template <typename TT> class Node { unsigned index[2]; TT num; Node<TT> *next[2]; public: Node( unsigned x = 0, unsigned y = 0 ) { index[0]=x; index[1]=y; next[0] = this; next[1] = this; } Node( unsigned x, unsigned y, TT d ) { index[0]=x; index[1]=y; num=d; next[0] = this; next[1] = this; } Node( const Node &n ) { index[0] = n.index[0]; index[1] = n.index[1]; num = n.num; next[0] = next[1] = this; } ~Node() {} friend class List; }; }; #include "List.cpp" #endif the exact error log is the following: In file included from main.cpp:1: List.h: In member function ‘bool List<T>::switchable_frame<DIM>::next_frame()’: List.h:77: error: ‘caret’ was not declared in this scope

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