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  • Parent variable inheritance methods Unity3D/C#

    - by Timothy Williams
    I'm creating a system where there is a base "Hero" class and each hero inherits from that with their own stats and abilities. What I'm wondering is, how could I call a variable from one of the child scripts in the parent script (something like maxMP = MP) or call a function in a parent class that is specified in each child class (in the parent update is alarms() in the child classes alarms() is specified to do something.) Is this possible at all? Or not? Thanks.

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  • Implicit and Explicit implementations for Multiple Interface inheritance

    Following C#.NET demo explains you all the scenarios for implementation of Interface methods to classes. There are two ways you can implement a interface method to a class. 1. Implicit Implementation 2. Explicit Implementation. Please go though the sample. using System; namespace ImpExpTest {     class Program     {         static void Main(string[] args)         {             C o3 = new C();             Console.WriteLine(o3.fu());             I1 o1 = new C();             Console.WriteLine(o1.fu());             I2 o2 = new C();             Console.WriteLine(o2.fu());             var o4 = new C();       //var is considered as C             Console.WriteLine(o4.fu());             var o5 = (I1)new C();   //var is considered as I1             Console.WriteLine(o5.fu());             var o6 = (I2)new C();   //var is considered as I2             Console.WriteLine(o6.fu());             D o7 = new D();             Console.WriteLine(o7.fu());             I1 o8 = new D();             Console.WriteLine(o8.fu());             I2 o9 = new D();             Console.WriteLine(o9.fu());         }     }     interface I1     {         string fu();     }     interface I2     {         string fu();     }     class C : I1, I2     {         #region Imicitly Defined I1 Members         public string fu()         {             return "Hello C"         }         #endregion Imicitly Defined I1 Members         #region Explicitly Defined I1 Members         string I1.fu()         {             return "Hello from I1";         }         #endregion Explicitly Defined I1 Members         #region Explicitly Defined I2 Members         string I2.fu()         {             return "Hello from I2";         }         #endregion Explicitly Defined I2 Members     }     class D : C     {         #region Imicitly Defined I1 Members         public string fu()         {             return "Hello from D";         }         #endregion Imicitly Defined I1 Members     } } Output:- Hello C Hello from I1 Hello from I2 Hello C Hello from I1 Hello from I2 Hello from D Hello from I1 Hello from I2 span.fullpost {display:none;}

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  • Website inheritance of ownership question

    - by Adrian Denham
    I paid for a web site for my motel business, then due to my landlord actions I was placed in a position to file for bankrupcy. I asked my IT manager and web developer to close down the web site for the business. He has since then sold my web site to the new owners. I took all the photos myself and I am in at least 4 of the photos on the site. There are no changes to the site as I left it and it now states that it is under the copyright on the new owners? I am not sure what I should do as this happen 10 months ago and I have just found this out. Thank you for your help, I am in Australia.

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  • Implenting ActiveRecord with inheritance?

    - by King
    I recently converted an old application that was using XML files as the data store to use SQL instead. To avoid a lot of changes I basically created ActiveRecord style classes that inherited from the original business objects. For example SomeClassRecord :SomeClass //ID Property //Save method I then used this new class in place of the other one, because of polymorphism I didn't need to change any methods that took SomeClass as a parameter. Would this be considered 'Bad'? What would be a better alternative?

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  • I have found an inheritance.

    <b>Technology & Life Integration:</b> "You may not know me as I received your attention from a browser link. This is very important so please continue reading. This letter has the possibility of changing your life. With your help we can realise that dream."

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  • CSS-Specifity and CSS Inheritance (concrete question)?

    - by jens
    Hello, i would by thankful for an official link (and section) of the specification for CSS, that explains if: .one two h1 {color:green;font-family:arial;} /*case 1 */ .one two h1 {color:blue;} /*case 2*/ will result in (when evaluated by the browser) .one two h1 {color:blue;font-family:arial;} /*case 3*/ or will it be: .one two h1 {color:blue;} /*case 4*/ ==I have read a lot about inheritance, specifity, cascading etc but I still have not found for the given example which rules apply here. In regard to specifity both elements are equal in specifity the case2 will be the most specify one (as it is equal specific but the last one). But does specifity always apply to the whole selector with ALL properties defined. Or only the the properties that are are in "competition" (and declared in both). thanks!!!!

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  • OOP concept: is it possible to update the class of an instantiated object?

    - by Federico
    I am trying to write a simple program that should allow a user to save and display sets of heterogeneous, but somehow related data. For clarity sake, I will use a representative example of vehicles. The program flow is like this: The program creates a Garage object, which is basically a class that can contain a list of vehicles objects Then the users creates Vehicles objects, these Vehicles each have a property, lets say License Plate Nr. Once created, the Vehicle object get added to a list within the Garage object --Later on--, the user can specify that a given Vehicle object is in fact a Car object or a Truck object (thus giving access to some specific attributes such as Number of seats for the Car, or Cargo weight for the truck) At first sight, this might look like an OOP textbook question involving a base class and inheritance, but the problem is more subtle because at the object creation time (and until the user decides to give more info), the computer doesn't know the exact Vehicle type. Hence my question: how would you proceed to implement this program flow? Is OOP the way to go? Just to give an initial answer, here is what I've came up until now. There is only one Vehicle class and the various properties/values are handled by the main program (not the class) through a dictionary. However, I'm pretty sure that there must be a more elegant solution (I'm developing using VB.net): Public Class Garage Public GarageAdress As String Private _ListGarageVehicles As New List(Of Vehicles) Public Sub AddVehicle(Vehicle As Vehicles) _ListGarageVehicles.Add(Vehicle) End Sub End Class Public Class Vehicles Public LicensePlateNumber As String Public Enum VehicleTypes Generic = 0 Car = 1 Truck = 2 End Enum Public VehicleType As VehicleTypes Public DictVehicleProperties As New Dictionary(Of String, String) End Class NOTE that in the example above the public/private modifiers do not necessarily reflect the original code

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  • What OO Design to use ( is there a Design Pattern )?

    - by Blundell
    I have two objects that represent a 'Bar/Club' ( a place where you drink/socialise). In one scenario I need the bar name, address, distance, slogon In another scenario I need the bar name, address, website url, logo So I've got two objects representing the same thing but with different fields. I like to use immutable objects, so all the fields are set from the constructor. One option is to have two constructors and null the other fields i.e: class Bar { private final String name; private final Distance distance; private final Url url; public Bar(String name, Distance distance){ this.name = name; this.distance = distance; this.url = null; } public Bar(String name, Url url){ this.name = name; this.distance = null; this.url = url; } // getters } I don't like this as you would have to null check when you use the getters In my real example the first scenario has 3 fields and the second scenario has about 10, so it would be a real pain having two constructors, the amount of fields I would have to declare null and then when the object are in use you wouldn't know which Bar you where using and so what fields would be null and what wouldn't. What other options do I have? Two classes called BarPreview and Bar? Some type of inheritance / interface? Something else that is awesome?

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  • How to maintain encapsulation with composition in C++?

    - by iFreilicht
    I am designing a class Master that is composed from multiple other classes, A, Base, C and D. These four classes have absolutely no use outside of Master and are meant to split up its functionality into manageable and logically divided packages. They also provide extensible functionality as in the case of Base, which can be inherited from by clients. But, how do I maintain encapsulation of Master with this design? So far, I've got two approaches, which are both far from perfect: 1. Replicate all accessors: Just write accessor-methods for all accessor-methods of all classes that Master is composed of. This leads to perfect encapsulation, because no implementation detail of Master is visible, but is extremely tedious and makes the class definition monstrous, which is exactly what the composition should prevent. Also, adding functionality to one of the composees (is that even a word?) would require to re-write all those methods in Master. An additional problem is that inheritors of Base could only alter, but not add functionality. 2. Use non-assignable, non-copyable member-accessors: Having a class accessor<T> that can not be copied, moved or assigned to, but overrides the operator-> to access an underlying shared_ptr, so that calls like Master->A()->niceFunction(); are made possible. My problem with this is that it kind of breaks encapsulation as I would now be unable to change my implementation of Master to use a different class for the functionality of niceFunction(). Still, it is the closest I've gotten without using the ugly first approach. It also fixes the inheritance issue quite nicely. A small side question would be if such a class already existed in std or boost. EDIT: Wall of code I will now post the code of the header files of the classes discussed. It may be a bit hard to understand, but I'll give my best in explaining all of it. 1. GameTree.h The foundation of it all. This basically is a doubly-linked tree, holding GameObject-instances, which we'll later get to. It also has it's own custom iterator GTIterator, but I left that out for brevity. WResult is an enum with the values SUCCESS and FAILED, but it's not really important. class GameTree { public: //Static methods for the root. Only one root is allowed to exist at a time! static void ConstructRoot(seed_type seed, unsigned int depth); inline static bool rootExists(){ return static_cast<bool>(rootObject_); } inline static weak_ptr<GameTree> root(){ return rootObject_; } //delta is in ms, this is used for velocity, collision and such void tick(unsigned int delta); //Interaction with the tree inline weak_ptr<GameTree> parent() const { return parent_; } inline unsigned int numChildren() const{ return static_cast<unsigned int>(children_.size()); } weak_ptr<GameTree> getChild(unsigned int index) const; template<typename GOType> weak_ptr<GameTree> addChild(seed_type seed, unsigned int depth = 9001){ GOType object{ new GOType(seed) }; return addChildObject(unique_ptr<GameTree>(new GameTree(std::move(object), depth))); } WResult moveTo(weak_ptr<GameTree> newParent); WResult erase(); //Iterators for for( : ) loop GTIterator& begin(){ return *(beginIter_ = std::move(make_unique<GTIterator>(children_.begin()))); } GTIterator& end(){ return *(endIter_ = std::move(make_unique<GTIterator>(children_.end()))); } //unloading should be used when objects are far away WResult unloadChildren(unsigned int newDepth = 0); WResult loadChildren(unsigned int newDepth = 1); inline const RenderObject& renderObject() const{ return gameObject_->renderObject(); } //Getter for the underlying GameObject (I have not tested the template version) weak_ptr<GameObject> gameObject(){ return gameObject_; } template<typename GOType> weak_ptr<GOType> gameObject(){ return dynamic_cast<weak_ptr<GOType>>(gameObject_); } weak_ptr<PhysicsObject> physicsObject() { return gameObject_->physicsObject(); } private: GameTree(const GameTree&); //copying is only allowed internally GameTree(shared_ptr<GameObject> object, unsigned int depth = 9001); //pointer to root static shared_ptr<GameTree> rootObject_; //internal management of a child weak_ptr<GameTree> addChildObject(shared_ptr<GameTree>); WResult removeChild(unsigned int index); //private members shared_ptr<GameObject> gameObject_; shared_ptr<GTIterator> beginIter_; shared_ptr<GTIterator> endIter_; //tree stuff vector<shared_ptr<GameTree>> children_; weak_ptr<GameTree> parent_; unsigned int selfIndex_; //used for deletion, this isn't necessary void initChildren(unsigned int depth); //constructs children }; 2. GameObject.h This is a bit hard to grasp, but GameObject basically works like this: When constructing a GameObject, you construct its basic attributes and a CResult-instance, which contains a vector<unique_ptr<Construction>>. The Construction-struct contains all information that is needed to construct a GameObject, which is a seed and a function-object that is applied at construction by a factory. This enables dynamic loading and unloading of GameObjects as done by GameTree. It also means that you have to define that factory if you inherit GameObject. This inheritance is also the reason why GameTree has a template-function gameObject<GOType>. GameObject can contain a RenderObject and a PhysicsObject, which we'll later get to. Anyway, here's the code. class GameObject; typedef unsigned long seed_type; //this declaration magic means that all GameObjectFactorys inherit from GameObjectFactory<GameObject> template<typename GOType> struct GameObjectFactory; template<> struct GameObjectFactory<GameObject>{ virtual unique_ptr<GameObject> construct(seed_type seed) const = 0; }; template<typename GOType> struct GameObjectFactory : GameObjectFactory<GameObject>{ GameObjectFactory() : GameObjectFactory<GameObject>(){} unique_ptr<GameObject> construct(seed_type seed) const{ return unique_ptr<GOType>(new GOType(seed)); } }; //same as with the factories. this is important for storing them in vectors template<typename GOType> struct Construction; template<> struct Construction<GameObject>{ virtual unique_ptr<GameObject> construct() const = 0; }; template<typename GOType> struct Construction : Construction<GameObject>{ Construction(seed_type seed, function<void(GOType*)> func = [](GOType* null){}) : Construction<GameObject>(), seed_(seed), func_(func) {} unique_ptr<GameObject> construct() const{ unique_ptr<GameObject> gameObject{ GOType::factory.construct(seed_) }; func_(dynamic_cast<GOType*>(gameObject.get())); return std::move(gameObject); } seed_type seed_; function<void(GOType*)> func_; }; typedef struct CResult { CResult() : constructions{} {} CResult(CResult && o) : constructions(std::move(o.constructions)) {} CResult& operator= (CResult& other){ if (this != &other){ for (unique_ptr<Construction<GameObject>>& child : other.constructions){ constructions.push_back(std::move(child)); } } return *this; } template<typename GOType> void push_back(seed_type seed, function<void(GOType*)> func = [](GOType* null){}){ constructions.push_back(make_unique<Construction<GOType>>(seed, func)); } vector<unique_ptr<Construction<GameObject>>> constructions; } CResult; //finally, the GameObject class GameObject { public: GameObject(seed_type seed); GameObject(const GameObject&); virtual void tick(unsigned int delta); inline Matrix4f trafoMatrix(){ return physicsObject_->transformationMatrix(); } //getter inline seed_type seed() const{ return seed_; } inline CResult& properties(){ return properties_; } inline const RenderObject& renderObject() const{ return *renderObject_; } inline weak_ptr<PhysicsObject> physicsObject() { return physicsObject_; } protected: virtual CResult construct_(seed_type seed) = 0; CResult properties_; shared_ptr<RenderObject> renderObject_; shared_ptr<PhysicsObject> physicsObject_; seed_type seed_; }; 3. PhysicsObject That's a bit easier. It is responsible for position, velocity and acceleration. It will also handle collisions in the future. It contains three Transformation objects, two of which are optional. I'm not going to include the accessors on the PhysicsObject class because I tried my first approach on it and it's just pure madness (way over 30 functions). Also missing: the named constructors that construct PhysicsObjects with different behaviour. class Transformation{ Vector3f translation_; Vector3f rotation_; Vector3f scaling_; public: Transformation() : translation_{ 0, 0, 0 }, rotation_{ 0, 0, 0 }, scaling_{ 1, 1, 1 } {}; Transformation(Vector3f translation, Vector3f rotation, Vector3f scaling); inline Vector3f translation(){ return translation_; } inline void translation(float x, float y, float z){ translation(Vector3f(x, y, z)); } inline void translation(Vector3f newTranslation){ translation_ = newTranslation; } inline void translate(float x, float y, float z){ translate(Vector3f(x, y, z)); } inline void translate(Vector3f summand){ translation_ += summand; } inline Vector3f rotation(){ return rotation_; } inline void rotation(float pitch, float yaw, float roll){ rotation(Vector3f(pitch, yaw, roll)); } inline void rotation(Vector3f newRotation){ rotation_ = newRotation; } inline void rotate(float pitch, float yaw, float roll){ rotate(Vector3f(pitch, yaw, roll)); } inline void rotate(Vector3f summand){ rotation_ += summand; } inline Vector3f scaling(){ return scaling_; } inline void scaling(float x, float y, float z){ scaling(Vector3f(x, y, z)); } inline void scaling(Vector3f newScaling){ scaling_ = newScaling; } inline void scale(float x, float y, float z){ scale(Vector3f(x, y, z)); } void scale(Vector3f factor){ scaling_(0) *= factor(0); scaling_(1) *= factor(1); scaling_(2) *= factor(2); } Matrix4f matrix(){ return WMatrix::Translation(translation_) * WMatrix::Rotation(rotation_) * WMatrix::Scale(scaling_); } }; class PhysicsObject; typedef void tickFunction(PhysicsObject& self, unsigned int delta); class PhysicsObject{ PhysicsObject(const Transformation& trafo) : transformation_(trafo), transformationVelocity_(nullptr), transformationAcceleration_(nullptr), tick_(nullptr) {} PhysicsObject(PhysicsObject&& other) : transformation_(other.transformation_), transformationVelocity_(std::move(other.transformationVelocity_)), transformationAcceleration_(std::move(other.transformationAcceleration_)), tick_(other.tick_) {} Transformation transformation_; unique_ptr<Transformation> transformationVelocity_; unique_ptr<Transformation> transformationAcceleration_; tickFunction* tick_; public: void tick(unsigned int delta){ tick_ ? tick_(*this, delta) : 0; } inline Matrix4f transformationMatrix(){ return transformation_.matrix(); } } 4. RenderObject RenderObject is a base class for different types of things that could be rendered, i.e. Meshes, Light Sources or Sprites. DISCLAIMER: I did not write this code, I'm working on this project with someone else. class RenderObject { public: RenderObject(float renderDistance); virtual ~RenderObject(); float renderDistance() const { return renderDistance_; } void setRenderDistance(float rD) { renderDistance_ = rD; } protected: float renderDistance_; }; struct NullRenderObject : public RenderObject{ NullRenderObject() : RenderObject(0.f){}; }; class Light : public RenderObject{ public: Light() : RenderObject(30.f){}; }; class Mesh : public RenderObject{ public: Mesh(unsigned int seed) : RenderObject(20.f) { meshID_ = 0; textureID_ = 0; if (seed == 1) meshID_ = Model::getMeshID("EM-208_heavy"); else meshID_ = Model::getMeshID("cube"); }; unsigned int getMeshID() const { return meshID_; } unsigned int getTextureID() const { return textureID_; } private: unsigned int meshID_; unsigned int textureID_; }; I guess this shows my issue quite nicely: You see a few accessors in GameObject which return weak_ptrs to access members of members, but that is not really what I want. Also please keep in mind that this is NOT, by any means, finished or production code! It is merely a prototype and there may be inconsistencies, unnecessary public parts of classes and such.

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  • Singleton with inheritance, Derived class is not able to get instantiated in parent?

    - by yesraaj
    Below code instantiates a derived singleton object based on environment variable. The compiler errors saying error C2512: 'Dotted' : no appropriate default constructor. I don't understand what the compiler is complaining about. #include <stdlib.h> #include <iostream> #include <string> using namespace std; class Dotted; class Singleton{ public: static Singleton instant(){ if (!instance_) { char * style = getenv("STYLE"); if (!style){ if (strcmp(style,"dotted")==0) { instance_ = new Dotted(); return *instance_; } } else{ instance_ = new Singleton(); return *instance_; } } return *instance_; } void print(){cout<<"Singleton";} ~Singleton(){}; protected: Singleton(){}; private: static Singleton * instance_; Singleton(const Singleton & ); void operator=(const Singleton & ); }; class Dotted:public Singleton{ public: void print(){cout<<"Dotted";} protected: Dotted(); }; Dotted::Dotted():Singleton(){} int main(){ Singleton::instant().print(); cin.get(); }

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  • Why doesn't interface inheritance work when writing shell extensions in c#?

    - by Factor Mystic
    According to this article about writing shell extensions in .Net, inheriting the shell interfaces as you might naturally do when writing code doesn't work. I've observed this in my own code as well. Doesn't work: public interface IPersist { // stuff specific only to IPersist } public interface IPersistFolder : IPersist { // stuff specific only to IPersistFolder } Does work: public interface IPersistFolder { // stuff specific to IPersist only // stuff specific to IPersistFolder only } The article notes this fact: Lo and behold, it worked! Notice that I've abandoned any idea that IPersistFolder is inherited from anything at all and just included the stubs from IPersist right in its definition. In all candor, I can't tell you why this is but it definitely works just fine and shouldn't give you any problems. So my I'll ask the question this guy didn't know; why didn't the original code work?

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  • Help with these warnings. [inheritance].

    - by sil3nt
    Hello there. I have a set of code, which mimics a basic library cataloging system. There is a base class named items, in which the the general id,title and year variables are defined and 3 other derived classes (DVD,Book and CD). Base [Items] Derived [DVD,Book,CD]. The programs runs, however I get the following warnings, I'm not sure how to fix these. "C:\Program Files\gcc\bin/g++" -Os -mconsole -g -Wall -Wshadow -fno-common mainA4.cpp -o mainA4.exe In file included from mainA4.cpp:5: a4.h: In constructor `DVD::DVD(int, std::string, int, std::string)': a4.h:28: warning: `DVD::director' will be initialized after a4.h:32: warning: base `Items' a4.h:32: warning: when initialized here a4.h: In constructor `Book::Book(int, std::string, int, std::string, int)': a4.h:48: warning: `Book::numPages' will be initialized after a4.h:52: warning: base `Items' a4.h:52: warning: when initialized here a4.h: In constructor `CD::CD(int, std::string, int, std::string, int)': a4.h:66: warning: `CD::numSongs' will be initialized after a4.h:70: warning: base `Items' a4.h:70: warning: when initialized here Exit code: 0

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  • Class inheritance in PHP 5.2: Overriding static variable in extension class?

    - by Christoffer
    Hi, I need to bea be able to use a static variable set in a class that extends a base class... from the base class. Consider this: class Animal { public static $color = 'black'; public static function get_color() { return self::$color; } } class Dog { public static $color = 'brown'; } echo Animal::get_color(); // prints 'black' echo Dog::get_color(); // also prints 'black' This works wonderfully in PHP 5.3.x (Dog::get_color() prints 'brown') since it has late static binding. But my production server runs PHP 5.2.11 and so I need to adapt my script. Is there a somewhat pretty workaround to solve this issue? Cheers! Christoffer

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  • inheritance confusion. Adding a special class for making errors obvious on form validation

    - by aslum
    So I've got a form... The relevant CSS is (I think): .libform input { background-color:transparent; color:#000; border-left:0; border-right:0; border-top:0; border-bottom: 1px solid #555; margin: 0 5px 1px 5px; display:inline-block; } .libform input:focus { border:0; border-bottom: 1px dotted #000; color:#939; background-color:#fed; } .error { border-bottom: 1px solid red; } Form field: <? if ($name=="") {$nameerror="error";}?> <input name="name" type="text" class="<?php echo $nameerror;?>" value="<?echo $name;?>" id="name"> I'd like for when they've left the field blank the input button's underline to change from black to red. But it doesn't seem to inherit right. What am I doing wrong?

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  • How is it possible the class inheritance in namespaces using Ruby on Rails 3?

    - by user502052
    In my RoR3 application I have a namespace called NS1 so that I have this filesystem structure: ROOT_RAILS/controllers/ ROOT_RAILS/controllers/application_controller.rb ROOT_RAILS/controllers/ns/ ROOT_RAILS/controllers/ns/ns_controller.rb ROOT_RAILS/controllers/ns/names_controller.rb ROOT_RAILS/controllers/ns/surnames_controller.rb I wuold like that 'ns_controller.rb' inherits from application controller, so in 'ns_controller.rb' file I have: class Ns::NsController < ApplicationController ... end Is this the right approach? Anyway if I have this situation... in 'application_controller.rb' class ApplicationController < ActionController::Base @profile = Profile.find(1) end in 'ns_controller.rb' class Ns::NsController < ApplicationController @name = @profile.name @surname = @profile.surname end ... '@name' and '@surname' variables are not set. Why?

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  • Is there a mean to specify specialization-genralization (inheritance) of actors in UML?

    - by Ivan
    I am just starting to use UML and have came to the following question: Some actors clearly are specialized versions of a natural entity. For example I've got Administrator and User actors which are clearly nothing but different roles of a user, Authorizer and Dispatcher which are services (and are going to be implemented this way). Should I just ignore these facts while modelling actors and use cases or specify it some way? I think I could make good use of such a specification to facilitate code generation.

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  • Correct CSS inheritance behavior for properties that aren't inherited?

    - by Chris
    So say we you have a CSS property that is not inherited by default. We'll call it "foo" and its default value is "black". Then we make the following html. <div id="div1" style="foo: red;"> <div id="div2"> <div id="div3" style="foo: inherit;"> </div> </div> </div> Since this property does not inherit by default, you'd think that in div2, "foo" must be "black" - the default value because it does not inherit by default. But ... in div3 should the value for "foo" inherit "black" from its parent that did not inherit foo, or should it inherit "red" from its grandparent because its parent did not specify foo? I need to know because I'm trying to implement something exactly to the spec.

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  • Objective-C inheritance; calling overriden method from superclass?

    - by anshuchimala
    Hello, I have an Objective-C class that has a method that is meant to be overridden, which is uses in a different method. Something like this: @interface BaseClass - (id)overrideMe; - (void)doAwesomeThings; @end @implementation BaseClass - (id)overrideMe { [self doesNotRecognizeSelector:_cmd]; return nil; } - (void)doAwesomeThings { id stuff = [self overrideMe]; /* do stuff */ } @end @interface SubClass : BaseClass @end @implementation SubClass - (id)overrideMe { /* Actually do things */ return <something>; } @end However, when I create a SubClass and try to use it, it still calls overrideMe on the BaseClass and crashes due to doesNotRecognizeSelector:. (I'm not doing a [super overrideMe] or anything stupid like that). Is there a way to get BaseClass to call the overridden overrideMe?

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  • Is it possible to use inheritance in this situation? (Java)

    - by they changed my name
    I have ClassA and ClassB, with ClassA being the superclass. ClassA uses NodeA, ClassB uses NodeB. First problem: method parameters. ClassB needs NodeB types, but I can't cast from the subclass to the superclass. That means I can't set properties which are unique to NodeB's. Second problem: When I need to add nodes toClassB, I have to instantiate a new NodeB. But, I can't do this in the superclass, so I'd have to rewrite the insertion to use NodeB. Is there a way around it or am I gonna have to rewrite the whole thing?

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  • Inherit one instance variable from the global scope

    - by Julian
    I'm using Curses to create a command line GUI with Ruby. Everything's going well, but I have hit a slight snag. I don't think Curses knowledge (esoteric to be fair) is required to answer this question, just Ruby concepts such as objects and inheritance. I'm going to explain my problem now, but if I'm banging on, just look at the example below. Basically, every Window instance needs to have .close called on it in order to close it. Some Window instances have other Windows associated with it. When closing a Window instance, I want to be able to close all of the other Window instances associated with it at the same time. Because associated Windows are generated in a logical fashion, (I append the name with a number: instance_variable_set(self + integer, Window.new(10,10,10,10)) ), it's easy to target generated windows, because methods can anticipate what assosiated windows will be called, (I can recreate the instance variable name from scratch, and almost query it: instance_variable_get(self + integer). I have a delete method that handles this. If the delete method is just a normal, global method (called like this: delete_window(@win543) then everything works perfectly. However, if the delete method is an instance method, which it needs to be in-order to use the self keyword, it doesn't work for a very clear reason; it can 'query' the correct instance variable perfectly well (instance_variable_get(self + integer)), however, because it's an instance method, the global instances aren't scoped to it! Now, one way around this would obviously be to simply make a global method like this: delete_window(@win543). But I have attributes associated with my window instances, and it all works very elegantly. This is very simplified, but it literally translates the problem exactly: class Dog def speak woof end end def woof if @dog_generic == nil puts "@dog_generic isn't scoped when .woof is called from a class method!\n" else puts "@dog_generic is scoped when .woof is called from the global scope. See:\n" + @dog_generic end end @dog_generic = "Woof!" lassie = Dog.new lassie.speak #=> @dog_generic isn't scoped when .woof is called from an instance method!\n woof #=> @dog_generic is scoped when .woof is called from the global scope. See:\nWoof! TL/DR: I need lassie.speak to return this string: "@dog_generic is scoped when .woof is called from the global scope. See:\nWoof!" @dog_generic must remain as an insance variable. The use of Globals or Constants is not acceptable. Could woof inherit from the Global scope? Maybe some sort of keyword: def woof < global # This 'code' is just to conceptualise what I want to do, don't take offence! end Is there some way the .woof method could 'pull in' @dog_generic from the global scope? Will @dog_generic have to be passed in as a parameter?

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  • cannot override a concrete member without a third member that's overridden by both

    - by huynhjl
    What does the following error message mean? cannot override a concrete member without a third member that's overridden by both (this rule is designed to prevent ``accidental overrides''); I was trying to do stackable trait modifications. It's a little bit after the fact since I already have a hierarchy in place and I'm trying to modify the behavior without having to rewrite a lot of code. I have a base class called AbstractProcessor that defines an abstract method sort of like this: class AbstractProcessor { def onPush(i:Info): Unit } I have a couple existing traits, to implement different onPush behaviors. trait Pass1 { def onPush(i:Info): Unit = { ... } } trait Pass2 { def onPush(i:Info): Unit = { ... } } So that allows me to use new AbstractProcessor with Pass1 or new AbstractProcessor with Pass2. Now I would like to do some processing before and after the onPush call in Pass1 and Pass2 while minimizing code changes to AbstractProcessor and Pass1 and Pass2. I thought of creating a trait that does something like this: trait Custom extends AbstractProcessor { abstract override def onPush(i:Info): Unit = { // do stuff before super.onPush(i) // do stuff after } And using it with new AbstractProcessor with Pass1 with Custom and I got that error message.

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  • getting a "default" concrete class that implements an interface

    - by Roger Joys
    I am implementing a custom (and generic) Json.net serializer and hit a bump in the road that I could use some help on. When the deserializer is mapping to a property that is an interface, how can I best determine what sort of object to construct to deserialize to to place into the interface property. I have the following: [JsonConverter(typeof(MyCustomSerializer<foo>))] class foo { int Int1 { get; set; } IList<string> StringList {get; set; } } My serializer properly serializes this object, and but when it comes back in, and I try to map the json parts to to object, I have a JArray and an interface. I am currently instantiating anything enumerable like List as theList = Activator.CreateInstance(property.PropertyType); This works create to work with in the deserialization process, but when the property is IList, I get runtime complaints (obviously) about not being able to instantiate an interface. So how would I know what type of concrete class to create in a case like this? Thank you

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  • How to layout class definition when inheriting from multiple interfaces

    - by gabr
    Given two interface definitions ... IOmniWorkItem = interface ['{3CE2762F-B7A3-4490-BF22-2109C042EAD1}'] function GetData: TOmniValue; function GetResult: TOmniValue; function GetUniqueID: int64; procedure SetResult(const value: TOmniValue); // procedure Cancel; function DetachException: Exception; function FatalException: Exception; function IsCanceled: boolean; function IsExceptional: boolean; property Data: TOmniValue read GetData; property Result: TOmniValue read GetResult write SetResult; property UniqueID: int64 read GetUniqueID; end; IOmniWorkItemEx = interface ['{3B48D012-CF1C-4B47-A4A0-3072A9067A3E}'] function GetOnWorkItemDone: TOmniWorkItemDoneDelegate; function GetOnWorkItemDone_Asy: TOmniWorkItemDoneDelegate; procedure SetOnWorkItemDone(const Value: TOmniWorkItemDoneDelegate); procedure SetOnWorkItemDone_Asy(const Value: TOmniWorkItemDoneDelegate); // property OnWorkItemDone: TOmniWorkItemDoneDelegate read GetOnWorkItemDone write SetOnWorkItemDone; property OnWorkItemDone_Asy: TOmniWorkItemDoneDelegate read GetOnWorkItemDone_Asy write SetOnWorkItemDone_Asy; end; ... what are your ideas of laying out class declaration that inherits from both of them? My current idea (but I don't know if I'm happy with it): TOmniWorkItem = class(TInterfacedObject, IOmniWorkItem, IOmniWorkItemEx) strict private FData : TOmniValue; FOnWorkItemDone : TOmniWorkItemDoneDelegate; FOnWorkItemDone_Asy: TOmniWorkItemDoneDelegate; FResult : TOmniValue; FUniqueID : int64; strict protected procedure FreeException; protected //IOmniWorkItem function GetData: TOmniValue; function GetResult: TOmniValue; function GetUniqueID: int64; procedure SetResult(const value: TOmniValue); protected //IOmniWorkItemEx function GetOnWorkItemDone: TOmniWorkItemDoneDelegate; function GetOnWorkItemDone_Asy: TOmniWorkItemDoneDelegate; procedure SetOnWorkItemDone(const Value: TOmniWorkItemDoneDelegate); procedure SetOnWorkItemDone_Asy(const Value: TOmniWorkItemDoneDelegate); public constructor Create(const data: TOmniValue; uniqueID: int64); destructor Destroy; override; public //IOmniWorkItem procedure Cancel; function DetachException: Exception; function FatalException: Exception; function IsCanceled: boolean; function IsExceptional: boolean; property Data: TOmniValue read GetData; property Result: TOmniValue read GetResult write SetResult; property UniqueID: int64 read GetUniqueID; public //IOmniWorkItemEx property OnWorkItemDone: TOmniWorkItemDoneDelegate read GetOnWorkItemDone write SetOnWorkItemDone; property OnWorkItemDone_Asy: TOmniWorkItemDoneDelegate read GetOnWorkItemDone_Asy write SetOnWorkItemDone_Asy; end; As noted in answers, composition is a good approach for this example but I'm not sure it applies in all cases. Sometimes I'm using multiple inheritance just to split read and write access to some property into public (typically read-only) and private (typically write-only) part. Does composition still apply here? I'm not really sure as I would have to move the property in question out from the main class and I'm not sure that's the correct way to do it. Example: // public part of the interface interface IOmniWorkItemConfig = interface function OnExecute(const aTask: TOmniBackgroundWorkerDelegate): IOmniWorkItemConfig; function OnRequestDone(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; function OnRequestDone_Asy(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; end; // private part of the interface IOmniWorkItemConfigEx = interface ['{42CEC5CB-404F-4868-AE81-6A13AD7E3C6B}'] function GetOnExecute: TOmniBackgroundWorkerDelegate; function GetOnRequestDone: TOmniWorkItemDoneDelegate; function GetOnRequestDone_Asy: TOmniWorkItemDoneDelegate; end; // implementing class TOmniWorkItemConfig = class(TInterfacedObject, IOmniWorkItemConfig, IOmniWorkItemConfigEx) strict private FOnExecute : TOmniBackgroundWorkerDelegate; FOnRequestDone : TOmniWorkItemDoneDelegate; FOnRequestDone_Asy: TOmniWorkItemDoneDelegate; public constructor Create(defaults: IOmniWorkItemConfig = nil); public //IOmniWorkItemConfig function OnExecute(const aTask: TOmniBackgroundWorkerDelegate): IOmniWorkItemConfig; function OnRequestDone(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; function OnRequestDone_Asy(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; public //IOmniWorkItemConfigEx function GetOnExecute: TOmniBackgroundWorkerDelegate; function GetOnRequestDone: TOmniWorkItemDoneDelegate; function GetOnRequestDone_Asy: TOmniWorkItemDoneDelegate; end;

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