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  • javascript inherance? with Private vars and methods too

    - by Totty
    Hy i need to inherent a class from another. Parent has private var "_data" and private method "_test" and public method "add" Now the child have a public method "add", that uses the private method from the parent "_test" and the private var "_data". How do i do this? var Parent = function(){ var _data = {}; var _test = function(){alert('test')}; this.add = function(){alert('add from parent')} } var Child = function(){ this.add = function(){// here uses the _data and _test from the Parent class alert('add from child') } } // something to inherent Child from Parent // instance Child and use the add method And i think im miss the prototype concept (http://stackoverflow.com/questions/892467/javascript-inheritance)

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  • C#: Preferred pattern for functions requiring arguments that implement two interfaces

    - by JS Bangs
    The argument to my function f() must implement two different interfaces that are not related to each other by inheritance, IFoo and IBar. I know of two different ways of doing this. The first is to declare an empty interface that inherits from both: public interface IFooBar : IFoo, IBar { // nothing to see here } public int f(IFooBar arg) { // etc. } This, of course, requires that the classes declare themselves as implementing IFooBar rather than IFoo and IBar separately. The second way is to make f() generic with a constraint: public int f<T>(T arg) where T : IFoo, IBar { // etc. } Which of these do you prefer, and why? Are there any non-obvious advantages or disadvantages to each?

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  • How to apply Abstract Factory Pattern ???

    - by Amit
    I am new to Design Pattern and I have a scenario here... and not sure as how to implement the pattern ... We have multiple vendors Philips, Onida... Each vendor (philips, onida...) may have different type of product i.e. Plasma or Normal TV I want specific product of each vendor using Abstract Factory Pattern... Thanks in advance for any help... My implementation so far... public enum TvType { Samsung = 0,LG = 1,Philips = 2, Sony = 3 } public enum Product { Plasma = 0,NormalTV = 1 } concrete class of each vendor.... that returns each product and also the interface that contains ProductInfo i.e. if Vendor is ... then it must have this product....

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  • C++ - what does the colon after a constructor mean?

    - by waitinforatrain
    I'd happily Google this but don't know what to call it to Google it. I have a piece of code here: class demo { private: unsigned char len, *dat; public: demo(unsigned char le = 5, unsigned char default) : len(le) { dat = new char[len]; for (int i = 0; i <= le; i++) dat[i] = default; } void ~demo(void) { delete [] *dat; } }; class newdemo : public demo { private: int *dat1; public: newdemo(void) : demo(0, 0) { *dat1 = 0; return 0; } }; (It's from a past exam paper and the question is to correct errors in the code so ignore errors!) My question is, what are the ": len(le) " and " : demo(0, 0)" called? Something to do with inheritance?

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  • Returning a ReadOnlyCollection from a method with an IList return type

    - by devoured elysium
    Here I have the following bit of code: private IList<IState> _states = new List<IState>(); private ReadOnlyCollection<IState> _statesViewer; public IList<IState> States { get { return _statesViewer; } } Generally it is preferable to return interfaces than the concrete classes themselves, but in this case, shouldn't I set as the return type of the States property a ReadOnlyCollection? Any user of my library will think it is possible to anything you can do with an IList if I set it as so, and that means adding elements. That is not true and I'm definitely breaking the contract exposing it as an IList. Am I right with this view or there is something else I am missing here?

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  • What's the best way to share one Entity Framework 4 data model among multiple applications (meant to

    - by Ivan
    A project (a "solution" to say in VS terms) of mine consists of an ASP.Net 4 Dynamic Data Entities web application, some WinForms applications, some WPF applications, some services. All they are intended to work with one SQL Server database, generated from an Entity Framework 4 model as table-per-type, with lots of inheritance and multiple self-referencing relations. Where do I best put my model? In a separate class library, a copy in every project, in one project, etc. What naming should I best use? Is it good idea to name it MySolution.MyClassLibrary.MySolutionEntities, or just MySolutionEntities or just MySolution? Can you share any useful experience on this subject?

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  • How do I dynamically assign the Model for a .find in Ruby on Rails?

    - by Angela
    I am trying to create a Single Table Inheritance. However, the Controller must be able to know which class to find or create. These are based on another class. For example, ContactEvent with type = Letter needs to grab attributes from a corresponding Model called Letter. Here's what I've tried to do and hit a snag, labelled below. I need to be able to dynamically call assign a value of EventClass so that it can be Letter.find(:conditions =) or Calls.find(:conditions =) depending on which type the controller is acting on. def new @contact_event = ContactEvent.new @contact_event.type = params[:event_type] # can be letter, call, postcard, email @contact_event.event_id = params[:event_id] # that ID to the corresponding Model @contact_event.contact_id = params[:contact] @EventClass = case when @contact_event.type == 'letter' then 'Letter' when @contact_event.type == 'call' then 'Call' when @contact_event.type == 'email' then 'Email' SNAG BELOW: @event = @EventClass.find(@contact_letter.letter_id) #how do I make @EventClass actually the Class?SNAG # substitution of variables into the body of the contact_event @event.body.gsub!("{FirstName}", @contact.first_name) @event.body.gsub!("{Company}", @contact.company_name) @evebt.body.gsub!("{Colleagues}", @colleagues.to_sentence) @contact_event.body = @event.body @contact_event.status = "sent" end

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  • Sex appeal of computer graphics: movie like UI systems [closed]

    - by anon
    It's well know that 1) the way computers actually work 2) the way computers are protrayed in movies are not the same. In particular (2) looks much much cooler than (1). Where can I learn more about making flashy, superficially useful but deepdown useless fancy graphics UIs like that? It's almost in the realm of "hollywood special effects" -- like fire/smoke/fire, but I don't want natural phenomenon; I want user interfaces. Concrete question: where can I learn about creating flashy, cool looking (though not necessairly useful) user interfaces? [Perferably in OpenGL]

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  • When using Dependency Injection with StructureMap how do I chooose among multiple constructors?

    - by Mark Rogers
    I'm trying to get structuremap to build Fluent Nhibernate's SessionSource object for some of my intregration tests. The only problem is that Fluent's concrete implementation of ISessionSource (SessionSource) has 3 constructors: public SessionSource(PersistenceModel model) { Initialize(new Configuration().Configure(), model); } public SessionSource(IDictionary<string, string> properties, PersistenceModel model) { Initialize(new Configuration().AddProperties(properties), model); } public SessionSource(FluentConfiguration config) { configuration = config.Configuration; sessionFactory = config.BuildSessionFactory(); dialect = Dialect.GetDialect(configuration.Properties); } I've tried configuring my ObjectFactory supplying an argument for the first constructor but it seems like it wants to try the second one. How do I configure my ObjectFactory so that I can choose the first constructor or perhaps even another one if I decide to use that?

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  • Using the JNotify library, how can you tell if a deleted file was a file or a directory?

    - by Moeri
    For those unfamiliar with JNotify, this is a library which provides an easy way to monitor events in a directory. For instance, when a file gets deleted in the selected folder, the method "fileDeleted" gets called, along with a few parameters. Here's an example of the fileDeleted method: public void fileDeleted(int wd, String rootPath, String name) { print("deleted " + rootPath + " : " + name); } Now, I would like to know if the deleted file was a file or directory. My usual approach is to create a new File object with the given path, and use the methods isFile() and isDirectory() However, since this file is already deleted, these methods always return false. So here's my concrete question: I have the path to a deleted file or directory, how can I tell wether it was a file or a directory? Is there a workaround to this? What's the best practice to do here? Thank you in advance.

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  • 'is instanceof' Interface bad design

    - by peterRit
    Say I have a class A class A { Z source; } Now, the context tells me that 'Z' can be an instance of different classes (say, B and C) which doesn't share any common class in their inheritance tree. I guess the naive approach is to make 'Z' an Interface class, and make classes B and C implement it. But something still doesn't convince me because every time an instance of class A is used, I need to know the type of 'source'. So all finishes in multiple 'ifs' making 'is instanceof' which doesn't sound quite nice. Maybe in the future some other class implements Z, and having hardcoded 'ifs' of this type definitely could break something. The escence of the problem is that I cannot resolve the issue by adding functions to Z, because the work done in each instance type of Z is different. I hope someone can give me and advice, maybe about some useful design pattern. Thanks

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  • VS 2010 Entity Repository Error

    - by Steve
    In my project I have it set up so that all the tables in the DB has the property "id" and then I have the entity objects inherit from the EntityBase class using a repository pattern. I then set the inheritance modifier for "id" property in the dbml file o/r designer to "overrides" Public MustInherit Class EntityBase MustOverride Property id() As Integer End Class Public MustInherit Class RepositoryBase(Of T As EntityBase) Protected _Db As New DataClasses1DataContext Public Function GetById(ByVal Id As Integer) As T Return (From a In _Db.GetTable(Of T)() Where a.id = Id).SingleOrDefault End Function End Class Partial Public Class Entity1 Inherits EntityBase End Class Public Class TestRepository Inherits RepositoryBase(Of Entity1) End Class the line Return (From a In _Db.GetTable(Of T)() Where a.id = Id).SingleOrDefault however produces the error "Class member EntityBase.id is unmapped" when i use VS 2010 using the 4.0 framework but I never received that error with the old one. Any help would be greatly appreciated. Thanks in advance.

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  • Has anybody managed to teach themself strong OOP skills through mainly developing with JavaScript?

    - by yaya3
    I am trying to do this, I'm a full time front-end dev and am aware that I am struglling to achieve this. When I am referring to OOP skills I am referring to understanding and being familiar with concepts like inheritance, polymorphism, encapsulation, abstaction. I am aware that it may be more likely to achieve what I'm after by focusing on another language in my spare time. This is the plan, but I'd be really intrigued to hear if anybody has managed to achieve this purely through JavaScript and how you did it. It'd be even better to hear from strong OOP developers from who use different programming languages to know if they have worked with developers who have managed to achieve this.

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  • Propagate properties to parent control C#

    - by Martin Ch
    Is there any way how to propagate properties from child control into parent - so I can access property like - Parent.Property1 instead of Parent.Child.Property1 ? I cant use inheritance - my parent cant be extended child type - its inherited from different class. Also I dont wanna add code for each property from child to parent like: public object Property1 { get{ return Child.Property1; } set{ ChildProperty1 = value; } } Maybe using reflection - something like this? public PropertyInfo[] Properties { get{ return Child.GetType().GetProperties(); } set{ Child.GetType().GetProperties().SetValue() = value.GetValue()} } Thanks

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  • In C#: How to declare a generic Dictionary with a type as key and an enumeration of that type as val

    - by Marcel
    Hi all, I want to declare a dictionary that stores typed IEnumerable's of a specific type, with that exact type as key, like so: (Edited to follow johny g's comment) private IDictionary<Type, IEnumerable<T>> _dataOfType where T: BaseClass; //does not compile! The concrete classes I want to store, all derive from BaseClass, therefore the idea to use it as constraint. The compiler complains that it expects a semicolon after the member name. If it would work, I would expect this would make the later retrieval from the dictionary simple like: IEnumerable<ConcreteData> concreteData; _sitesOfType.TryGetValue(typeof(ConcreteType), out concreteData); How to define such a dictionary?

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  • WPF: Hidden parent and visible child

    - by oakskc
    As of last night, I decided to start learning about WPF and have been reading through a number of online tutorials and books. This is a huge shift. One feature that has fascinated me is the implicit property value inheritance. I know in the WinForms world, if a control is not visible then neither are any of the child controls. Same seems to be true in the WPF world, as expected. I wondered if explicitly setting the child control's Visibility property would allow for an invisible parent and visible child and it did not. Is this something that would be possible in WPF? Can you have a container control that is hidden with visible children? This is more an exercise of curiosity than anything. I'm still trying to wrap my head around a lot of what I've been reading.

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  • insert data into several tables

    - by csetzkorn
    Let us say I have a table (everything is very much simplified): create table OriginalData ( bla char(10) not null ) And I would like to insert its data (set based!) into two tables which model inheritance create table Statements ( Id int IDENTITY NOT NULL, ProposalDateTime DATETIME null ) create table Items ( StatementFk INT not null, ItemName NVARCHAR(255) null, primary key (StatementFk) ) Statements is the parent table and Items is the child table. I have no problem doing this with one row which involves the use of IDENT_CURRENT but I have no idea how to do this set based (i.e. enter several rows into both tables). Thanks. Best wishes, Christian

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  • Metric to measure object-orientedness

    - by Jono
    Is there a metric that can assist in determining the object-orientedness of a system or application? I've seen some pretty neat metrics in the .NET Reflector Add-ins codeplex project, but nothing like this yet. If such a metric doesn't exist, would it even be possible or useful? There are the 3 supposed tenets of object-oriented programming: encapsulation, inheritance, and polymorphism; a tool that ranked programs against these might be able to show areas of a C# (or similar) code base where the whole object-oriented ideal was discarded, and perhaps how many bugs are associated with that area versus the rest of the project.

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  • Resharper: how to force introducing new private fields at the bottom of the class?

    - by Igor Brejc
    Resharper offers a very useful introduce and initialize field xxx action when you specify a new parameter in a constructor like: Constructor (int parameter) The only (minor) nuisance is that it puts the new field at the beginning of the class - and I'm a fan of putting private parts as far away as possible from the prying eyes of strangers ;). If, however, you already have some private fields in the class, Resharper will put the new field "correctly" (note the quotes, I don't want to start a flame war over this issue) next to those, even if they are at the end of the class. Is there a way to force Resharper to always put new fields at the end of the class? UPDATE: OK, I forgot to mention I know about the "Type Members Layout in Options" feature, but some concrete help on how to modify the template to achieve fields placement would be nice.

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  • What's a good book for learning BCPL?

    - by paxdiablo
    A long time ago, I worked on some BCPL code (very similar to C although even more basic, difficult though that is to imagine). Now, as part of a compiler course, we're going to be setting assignments for building some of the parts of the compiler (lexical and semantic analysis) and I'd like to know what the community thinks is the best book for learning about the language (and concrete why you think it's the best). Not how to write compilers for it, just on how to program in it. It'll be up to the students themselves to figure out how best to develop a compiler. We're using BCPL since the chance of people being able to plagiarise code for a compiler is very slim. Any suggestions?

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  • Constructor Type Coercion in C++

    - by Robert Mason
    Take the following class: class mytype { double num; public: mytype(int a) { num = sqrt(a); } void print() { cout << num; } } Say there is a method which takes a mytype: void foo(mytype a) { a.print(); } Is it legal c++ (or is there a way to implement this) to call foo(4), which would (in theory) output 2? From what I can glean you can overload type casts from a user defined class, but not to. Can constructor do this in a standards-compliant manner (assuming, of course, the constructor is not explicit). Hopefully there is a way to in the end have this legal: int a; cin >> a; foo(a); Note: this is quite obviously not the actual issue, but just an example for posting purposes. I can't just overload the function because of inheritance and other program-specific issues.

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  • command design pattern usage

    - by sagie
    Hi. I've read 3 descriptions of the command design pattern: wikipedia, dofactory and source making. In all of them, the UML shows a relation between the client to the receiver & the concrete command, but no relation to the invoker. But in all 3 examples the client is the one that initiates the invoker and call its Execute method. I think that should be a relation to the invoker as well. Am I missing somthing in here? Maybe even a basic UML knowladge?

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  • Can I serialize a BitArray to XML?

    - by SimonNet
    Hello I have a business class which I need to serialize to xml. It has a BitArray property. I have decorated it with [XmlAttribute] but the serialization is failing with To be XML serializable, types which inherit from ICollection must have an implementation of Add(System.Boolean) at all levels of their inheritance hierarchy. System.Collections.BitArray does not implement Add(System.Boolean). I am not sure whether its possible to serialize to xml? If not what would be an efficient means of serializing the BitArray Thanks for looking

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  • Is is possible to intercept a constructor on a class you do not own?

    - by code poet
    Referring to my possible answer to this question: http://stackoverflow.com/questions/2907535/how-would-you-audit-asp-net-membership-tables-while-recording-what-user-made-the/2911616#2911616 Is it possible to intercept a call, coming from code you do not own, to a ctor on a sealed internal class that you do not own with the intention of manipulating the object before returning? Concrete example: SqlMembershipProvider, for all of it's data access, instantiates a connection helper class, System.Web.DataAccess.SqlConnectionHolder. The desired result is to intercept this instantiation and perform an operation on the public connection that is opened in the ctor of System.Web.DataAccess.SqlConnectionHolder before letting execution continue. Is this possible. If so, an brief example would be appreciated.

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  • How do I map repeating columns in NHibernate without creating duplicate properties

    - by Ian Oakes
    Given a database that has numerous repeating columns used for auditing and versioning, what is the best way to model it using NHibernate, without having to repeat each of the columns in each of the classes in the domain model? Every table in the database repeats these same nine columns, the names and types are identical and I don't want to replicate it in the domain model. I have read the docs and I saw the section on inheritance mapping but I couldn't see how to make it work in this scenario. This seems like a common scenario because nearly every database I've work on has had the four common audit columns (CreatedBy, CreateDate, UpdatedBy, UpdateDate) in nearly every table. This database is no different except that it introduces another five columns which are common to every table.

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