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  • What is the best way to "override" enums?

    - by Tyler
    I have a number of classes which extend an abstract class. The abstract parent class defines an enum with a set of values. Some of the subclasses inherit the parent class's enum values, but some of the subclasses need the enum values to be different. Is there any way to somehow override the enum for these particular subclasses, and if not, what is a good way to achieve what I'm describing? class ParentClass { private MyEnum m_EnumVal; public virtual MyEnum EnumVal { get { return m_EnumVal; } set { m_EnumVal = value; } } public enum MyEnum { a, b, c }; } class ChildClass : ParentClass { private MyEnum m_EnumVal; public virtual MyEnum EnumVal { get { return m_EnumVal; } set { m_EnumVal = value; } } public enum MyEnum { d, e, f }; }

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  • calling a function from a set of overloads depending on the dynamic type of an object

    - by Jasper
    I feel like the answer to this question is really simple, but I really am having trouble finding it. So here goes: Suppose you have the following classes: class Base; class Child : public Base; class Displayer { public: Displayer(Base* element); Displayer(Child* element); } Additionally, I have a Base* object which might point to either an instance of the class Base or an instance of the class Child. Now I want to create a Displayer based on the element pointed to by object, however, I want to pick the right version of the constructor. As I currently have it, this would accomplish just that (I am being a bit fuzzy with my C++ here, but I think this the clearest way) object->createDisplayer(); virtual void Base::createDisplayer() { new Displayer(this); } virtual void Child::createDisplayer() { new Displayer(this); } This works, however, there is a problem with this: Base and Child are part of the application system, while Displayer is part of the GUI system. I want to build the GUI system independently of the Application system, so that it is easy to replace the GUI. This means that Base and Child should not know about Displayer. However, I do not know how I can achieve this without letting the Application classes know about the GUI. Am I missing something very obvious or am I trying something that is not possible?

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  • How can one enforce calling a base class function after derived class constructor?

    - by Mike Elkins
    I'm looking for a clean C++ idiom for the following situation: class SomeLibraryClass { public: SomeLibraryClass() { /* start initialization */ } void addFoo() { /* we are a collection of foos */ } void funcToCallAfterAllAddFoos() { /* Making sure this is called is the issue */ } }; class SomeUserClass : public SomeLibraryClass { public: SomeUserClass() { addFoo(); addFoo(); addFoo(); // SomeUserClass has three foos. } }; class SomeUserDerrivedClass : public SomeUserClass { public: SomeUserDerrivedClass() { addFoo(); // This one has four foos. } }; So, what I really want is for SomeLibraryClass to enforce the calling of funcToCallAfterAllAddFoos at the end of the construction process. The user can't put it at the end of SomeUserClass::SomeUserClass(), that would mess up SomeUserDerrivedClass. If he puts it at the end of SomeUserDerrivedClass, then it never gets called for SomeUserClass. To further clarify what I need, imagine that /* start initialization */ acquires a lock, and funcToCallAfterAllAddFoos() releases a lock. The compiler knows when all the initializations for an object are done, but can I get at that information by some nice trick?

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  • C# private (hidden) base class

    - by Loadmaster
    It is possible to make a C# base class accessible only within the library assembly it's compiled into, while making other subclasses that inherit from it public? For example: using System.IO; class BaseOutput: Stream // Hidden base class { protected BaseOutput(Stream o) { ... } ...lots of common methods... } public class MyOutput: BaseOutput // Public subclass { public BaseOutput(Stream o): base(o) { ... } public override int Write(int b) { ... } } Here I'd like the BaseOutput class to be inaccessible to clients of my library, but allow the subclass MyOutput to be completely public. I know that C# does not allow base classes to have more restrictive access than subclasses, but is there some other legal way of achieving the same effect?

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  • Why can't I create an abstract constructor on an abstract C# class?

    - by Anthony D
    I am creating an abstract class. I want each of my derived classes to be forced to implement a specific signature of constructor. As such, I did what I would have done has I wanted to force them to implement a method, I made an abstract one. public abstract class A { abstract A(int a, int b); } However I get a message saying the abstract modifier is invalid on this item. My goal was to force some code like this. public class B : A { public B(int a, int b) : base(a, b) { //Some other awesome code. } } This is all C# .NET code. Can anyone help me out? Update 1 I wanted to add some things. What I ended up with was this. private A() { } protected A(int a, int b) { //Code } That does what some folks are saying, default is private, and the class needs to implement a constructor. However that doesn't FORCE a constructor with the signature A(int a, int b). public abstract class A { protected abstract A(int a, int b) { } } Update 2 I should be clear, to work around this I made my default constructor private, and my other constructor protected. I am not really looking for a way to make my code work. I took care of that. I am looking to understand why C# does not let you do this.

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  • Ignoring all line feeds in a FreeMarker template

    - by Will
    I'm trying out FreeMarker, not for a web application but to generate text within a desktop application. I'd like to get the text without any linefeeds, however it always appends a linefeed. For example, this would produce "blah blah\n" <#if docType=1> blah blah <#if docType=2> more blah <#/if> Any ideas? Bunching it all into one line works, but is horrible. Thanks.

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  • Nhibernate Common columns in base class

    - by sukh
    I want to design following scenario Base class (Id, Name, order, Value) 3 Derived classes derive1, derive2, derive3 inheriting properties from base There is no table for base class. And 1 table for each derived class. 3 tables have same columns. How can I create mapping file ignoring base class? Do I need to create 1 mapping file for each derived class? can I achieve this using only 1 mapping file?

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  • How to access the backing field of a base class using fluent nhibernate?

    - by Akk
    How do i set the Access Strategy in the mapping class to point to the base _photos field? public class Content { private IList<Photo> _photos; public Content() { _photos = new List<Photo>(); } public virtual IEnumerable<Photo> Photos { get { return _photos; } } public virtual void AddPhoto() {...} } public class Article : Content { public string Body {get; set;} } I am currently using the following to try and locate the backing field but an exception is thrown as it cannot be found. public class ArticleMap : ClassMap<Article> { HasManyToMany(x => x.Photos) .Access.CamelCaseField(Prefix.Underscore) //_photos //... } i tried moving the backing field _photos directly into the class and the access works. So how can i access the backing field of the base class?

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  • are there requirements for Struts setters beyond variable name matching?

    - by slk
    I have a model-driven Struts Web action: public class ModelDrivenAction<T extends Object> implements ModelDriven<T>, Preparable { protected Long id; protected T model; @Override public void prepare() {} public void setId(Long id) { this.id = id; } @Override public T getModel() { return model; } public void setModel(T model) { this.model = model; } } I have another action which is not currently model-driven: public class OtherAction implements Preparable { private ModelObj modelObj; private Long modelId; @Override public void prepare() { modelObj = repoService.retrieveModelById(modelId); } public void setModelId(Long modelId) { this.modelId = modelId; } } I wish to make it so, and would like to avoid having to track down all the instances in JavaScript where the action is passed a "modelId" parameter instead of "id" if at all possible. I thought this might work, so either modelId or id could be passed in: public class OtherAction extends ModelDrivenAction<ModelObj> { @Override public void prepare() { model = repoService.retrieveModelById(id); } public void setModelId(Long modelId) { this.id = modelId; } } However, server/path/to/other!method?modelId=123 is failing to set id. I thought so long as a setter matched a parameter name the Struts interceptor would call it on action invocation. Am I missing something here?

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  • Unable to bind in asp.net grid Template Column

    - by OneSmartGuy
    I am having trouble accessing the data field. I receive the error: Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control. I can get the value but using <%# getOpenJobs((string)Eval("ParentPart")) % but I need to use it in the if to display a certian picture if it passes the condition. Is there a better way to do this or am i just missing something simple? <telerik:GridTemplateColumn UniqueName="hasOpenJobs" HeaderText=""> <ItemTemplate> <% if (getOpenJobs((string)Eval("ParentPart")) > 1) { %> <img src="../images/job-icon.gif" alt="Open Jobs" /> <%} %> </ItemTemplate> </telerik:GridTemplateColumn>

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  • Reading a Text file in xcode

    - by Nicolaj Zefting
    First off, I'm a complete beginner. This might be a stupid question, but here it goes: I'm currently working on an App than contains Latin texts that the users can view and read. I'm using Xcode 4 with the storybord function. Theway the app is built: user selects author - then the book - then app shows the text. I am kind of confused because i need to have various text files, depending on the users choice.

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  • Should downcasting be avoided while using a class hierarchy in C++?

    - by neuviemeporte
    Let's say I'm writing an application which works with projects, and exposes different functionality depending on the type of the project. I have a hierarchy of classes for the different types of projects: class AbstractProject { }; class ProjectA : public AbstractProject { }; class ProjectB : public AbstractProject { }; class ProjectC : public AbstractProject { }; Now, I was planning to have an AbstractProject *_currentProject pointer as a member in the application's main class, pop up a dialog box on startup and based on the selection, do: _currentProject = new ProjectB(); // e.g. Later, I'll have to downcast the pointer to the specific type to utilize the functionality specific to different Project-s. Somehow this makes me feel uneasy. Is there a Better Way of doing this?

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  • Calling base class constructor

    - by The Void
    In the program below, is the line Derived(double y): Base(), y_(y) correct/allowed? That is, does it follow ANSI rules? #include <iostream> class Base { public: Base(): x_(0) { std::cout << "Base default constructor called" << std::endl; } Base(int x): x_(x) { std::cout << "Base constructor called with x = " << x << std::endl; } void display() const { std::cout << x_ << std::endl; } protected: int x_; }; class Derived: public Base { public: Derived(): Base(1), y_(1.2) { std::cout << "Derived default constructor called" << std::endl; } Derived(double y): Base(), y_(y) { std::cout << "Derived constructor called with y = " << y << std::endl; } void display() const { std::cout << Base::x_ << ", " << y_ << std::endl; } private: double y_; }; int main() { Base b1; b1.display(); Derived d1; d1.display(); std::cout << std::endl; Base b2(-9); b2.display(); Derived d2(-8.7); d2.display(); return 0; }

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  • Using Django.test.client to check template vars

    - by scott
    I've got a view that I'm trying to test with the Client object. Can I get to the variables I injected into the render_to_response of my view? Example View: def myView(request): if request.method == "POST": # do the search return render_to_response('search.html',{'results':results},context_instance=RequestContext(request)) else: return render_to_response('search.html',context_instance=RequestContext(request) Test: c = Client() response = c.post('/school/search/', {'keyword':'beagles'}) # how do I get to the 'results' variable??

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  • Base form controls not visible in child form

    - by Kildareflare
    Hello I'm using C#.Net and have a base form that is inherited by several forms. Until yesterday, when the child (derived) form was opened in the designer the base forms controls would be displayed and shown as locked. Now, however the form is simply blank. None of the base forms controls are visible in the designer. Everything compiles, builds and runs OK. Has anyone else seen this? I've tried placing a call to the base forms InitializeComponent method in the derived forms OnLoad method but to no avail.

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  • Are private members inherited in C#?

    - by Petr
    Just seen one tutorial saying that: Class Dog { private string Name; } Class SuperDog:Dog { private string Mood; } Then there was an UML displaying that SuperDog will inherit Name as well. I have tried but to me it seems that only public members are inherited. At least I could not access Name unless it was declared as public.

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  • C# casting question: from IEnumerable to custom type

    - by Sarah Vessels
    I have a custom class called Rows that implements IEnumerable<Row>. I often use LINQ queries on Rows instances: Rows rows = new Rows { row1, row2, row3 }; IEnumerable<Row> particularRows = rows.Where<Row>(row => condition); What I would like is to be able to do the following: Rows rows = new Rows { row1, row2, row3 }; Rows particularRows = (Rows)rows.Where<Row>(row => condition); However, I get a "System.InvalidCastException: Unable to cast object of type 'WhereEnumerableIterator1[NS.Row]' to type 'NS.Rows'". I do have a Rows constructor taking IEnumerable<Row>, so I could do: Rows rows = new Rows { row1, row2, row3 }; Rows particularRows = new Rows(rows.Where<Row>(row => condition)); This seems bulky, however, and I would love to be able to cast an IEnumerable<Row> to be a Rows since Rows implements IEnumerable<Row>. Any ideas?

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  • django filefield return filename only in template

    - by John
    I've got a field in my model of type FileField. This gives me an object of type type File, which has the following method: File.name: The name of the file including the relative path from MEDIA_ROOT. What I want is something like .filename that will only give me the filename and not the path as well something like: {% for download in downloads %} <div class="download"> <div class="title">{{download.file.filename}}</div> </div> {% endfor %} which would give something like myfile.jpg thanks

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  • Calling base Text method on custom TextBox

    - by The Demigeek
    I'm trying to create a CurrencyTextBox that inherits from TextBox. I'm seeing some really weird behavior that I just don't understand. After lots of testing, I think I can summarize as follows: In the class code, when I access base.Text (to get the textbox's text), I'm actually getting the return value of my overridden Text property. I thought the base keyword would ensure that the underlying object's methods get called. To demonstrate: public class cTestTextBox : System.Windows.Forms.TextBox { string strText = ""; public cTestTextBox() { SetVal("AAA"); base.Text = "TEST"; } public override string Text { get { string s = strText; s = "++" + s + "++"; return s; } } public void SetVal(string val) { strText = val; } } Place this control on a form and set a breakpoint on the constructor. Run the app. Hover your mouse over the base.Text expression. Note that the tooltip shows you the value of the overridden property, not the base property. Execute the SetVal() statement and again hover your mouse over the base.Text expression. Note that the tooltop shows you the value of the overridden property, not the base property. How do I reliably access the Text property of the textbox from which I'm inheriting?

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  • scala: defining a tratit and referencing the corresponding companion object

    - by opensas
    I'm trying to define a trait that uses the corresponding companion object, that is, the componion object of the class using the trait. for example, I have: :paste class Parent { def callMyCompanion = print(Parent.salute) } object Parent { def salute = "Hello from Parent companion object" } class Child extends Parent { } object Child { def salute = "Hello from Child companion object" } And then I create a parent object: scala> val p = new Parent() p: Parent = Parent@1ecf669 scala> p.callMyCompanion Hello from Parent companion object But with a child: scala> val c = new Child() c: Child = Child@4fd986 scala> c.callMyCompanion Hello from Parent companion object I'd like to get: Hello from Child companion object How can I achieve it???

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  • Iphone sdk - How to setup a 'template'

    - by Dave
    I've been working on a Cook Book App and I've been making each page individually which takes a really long time to do, I asked a question similar to this and it was brought to my attention that you can setup a way to automate the design process so all you need to do is input your data. Can someone please explain in as much detail as possible how you setup your xcode files/code to automate this process Thanks

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  • Templating Word Documents in C#

    - by NullGeo
    I was wondering if there is a library out there such that it could give me the ability to fill in word templates with custom values. For example: Following could be the content of the Word Document {Address} {PhoneNumber} Hello {Name}, How are you doing? In C# I would like to do something like this to replace all the placeholders in the Word document: using(WordDocument doc = WordDocument.Load("Mail.docx")){ var person = new {Name = "John Smith", Address="42 Wallaby Way, Sydney", PhoneNumber="555-555-5555"}; doc.Template(person); doc.Print(); } The resulting document would look like this: 42 Wallaby Way, Sydney 555-555-5555 Hello John Smith, How are you doing? Any libraries out there (preferably free) that let's me do this? Edit: I am not asking you to find anything that let's me do this. If that was the case, I would do a Google search by myself. Honestly, all I am asking is "has anybody used a library in the past to do this exact thing."

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  • Having troubles inheriting base class

    - by Nick
    When I inherit the base class, it's telling me there is no such class This is enhanced.h: class enhanced: public changeDispenser // <--------where error is occuring { public: void changeStatus(); // Function: Lets the user know how much of each coin is in the machine enhanced(int); // Constructor // Sets the Dollar amount to what the User wants void changeLoad(int); // Function: Loads what change the user requests into the Coin Machine int dispenseChange(int); // Function: Takes the users amount of cents requests and dispenses it to the user private: int dollar; }; This is enhanced.cpp: #include "enhanced.h" #include <iostream> using namespace std; enhanced::enhanced(int dol) { dollar = dol; } void enhanced::changeStatus() { cout << dollar << " dollars, "; changeDispenser::changeStatus(); } void enhanced::changeLoad(int d) { dollar = dollar + d; //changeDispenser::changeLoad; } This is changeDispenser.h: class changeDispenser { public: void changeStatus(); // Function: Lets the user know how much of each coin is in the machine changeDispenser(int, int, int, int); // Constructor // Sets the Quarters, Dimes, Nickels, and Pennies to what the User wants void changeLoad(int, int, int, int); // Function: Loads what change the user requests into the Coin Machine int dispenseChange(int); // Function: Takes the users amount of cents requests and dispenses it to the user private: int quarter; int dime; int nickel; int penny; }; I didn't include the driver file or the changeDispenser imp file, but in the driver, these are included #include "changeDispenser.h" #include "enhanced.h"

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