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• non-scalar type requested

  - by lego69

  can somebody please help me with an error conversion from `A' to non-scalar type `B' requested I have class A and derived from it B, but I have problems with these rows: A a(1); A *pb = new B(a); B b = *pb; //here I have an error thanks in advance for any help class A { protected: int player; public: A(int initPlayer = 0); A(const A&); A& operator=(const A&); virtual ~A(){}; virtual void foo(); void foo() const; operator int(); }; class B: public A { public: B(int initPlayer): A(initPlayer){}; ~B(){}; virtual void foo(); };

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• ASP webservice serialization of properties

  - by badra

  I got a class like this which gets returned from an ASP webservice: class Data { public int A { get; set; } public int B { get; set; } public int Sum { get { return A + B; } } } When I try to consume the webservice on the client side using Silverlight I only get the properties A and B but I also need Sum. I know I can't return any logic from a webservice, so the expected behavior was it will return the the Sum as a fixed/precalculated property in the client which is what I need. Any ideas except for redesigning my class? Thanks ...

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• Sharing base object with inheritance

  - by max

  I have class Base. I'd like to extend its functionality in a class Derived. I was planning to write: class Derived(Base): def __init__(self, base_arg1, base_arg2, derived_arg1, derived_arg2): super().__init__(base_arg1, base_arg2) # ... def derived_method1(self): # ... Sometimes I already have a Base instance, and I want to create a Derived instance based on it, i.e., a Derived instance that shares the Base object (doesn't re-create it from scratch). I thought I could write a static method to do that: b = Base(arg1, arg2) # very large object, expensive to create or copy d = Derived.from_base(b, derived_arg1, derived_arg2) # reuses existing b object but it seems impossible. Either I'm missing a way to make this work, or (more likely) I'm missing a very big reason why it can't be allowed to work. Can someone explain which one it is? [Of course, if I used composition rather than inheritance, this would all be easy to do. But I was hoping to avoid the delegation of all the Base methods to Derived through __getattr__.]

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• Which Java library lets me initialize an object's properties from a properties file?

  - by Kjetil Ødegaard

  Is there a Java library that lets you "deserialize" a properties file directly into an object instance? Example: say you have a file called init.properties: username=fisk password=frosk and a Java class with some properties: class Connection { private String username; private String password; public void setUsername(String username) { this.username = username; } public void setPassword(String password) { this.password = password; } } I want to do this: Connection c = MagicConfigurator.configure("init.properties", new Connection()) and have MagicConfigurator apply all the values from the properties file to the Connection instance. Is there a library with a class like this?

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• going to build a php MVC, what naming conventions do i need to be aware of?

  - by Haroldo

  I'm pretty new to OO PHP, however i get how it all works and am ready to start building an MVC for a big site i'm working on. I know it isnt necessary written that you must do it like this but there's gotta be some normal practises.... class names - camelcase? underscores? class files - same as class? url/post/get controll name - router.php? any other things i should be aware of before i embark?

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• App Engine: how would you... snapshotting entities

  - by Andrew B.

  Let's say you have two kinds, Message and Contact, related by a db.ListProperty of keys on Message. A user creates a message, adds some contacts as recipients, and emails the message. Later, the user deletes one of the contact entities that was a recipient of the message. Our application should delete the appropriate Contact entity, but we want to preserve the original recipient list for the message that was sent for the user's records. In essence, we want a snapshot of the message entity at the time it was sent. If we naively delete the contact entity, though, we lose snapshot integrity; if not, we are left with an invalid key. How would you handle this situation, either in controller logic or model changes? class User(db.Model): email = db.EmailProperty(required=True) class Contact(db.Model): email = db.EmailProperty(required=True) user = db.ReferenceProperty(User, collection_name='contacts') class Message(db.Model): recipients = db.ListProperty(db.Key) # contacts sender = db.ReferenceProperty(User, collection_name='messages') body = db.TextProperty() is_emailed = db.BooleanProperty(default=False)

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• C++ operator overloading doubt

  - by avd

  I have a code base, in which for Matrix class, these two definitions are there for () operator: template <class T> T& Matrix<T>::operator() (unsigned row, unsigned col) { ...... } template <class T> T Matrix<T>::operator() (unsigned row, unsigned col) const { ...... } One thing I understand is that the second one does not return the reference but what does const mean in the second declaration. Also which function is called when I do say mat(i,j)

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• Dynamic binding in C++

  - by chmike

  I'm implementing a CORBA like server. Each class has remotely callable methods and a dispatch method with two possible input, a string identifying the method or an integer which would be the index of the method in a table. A mapping of the string to the corresponding integer would be implemented by a map. The caller would send the string on the first call and get back the integer with the response so that it simply has to send the integer on subsequent calls. It is just a small optimization. The integer may be assigned dynamically on demand by the server object. The server class may be derived from another class with overridden virtual methods. What could be a simple and general way to define the method binding and the dispatch method ?

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• Calculate average in each group

  - by Gokul

  I am using the following class class Country { int CountryID {get; set;} List<City> city {get; set;} } class City { int CountryID {get; set; } string city {get; set;} int sqkm {get; set;} } Here's is some sample data for Country and City Country US UK Canada City CityC CityF CityA CityB CityG CityD CityE I am populating using List<Country> countries = new List<Country> { new Country() { CountryID = "US", city = new List<City> { new City() {CountryID = "US", City ="CityF", sqkm = 2803 }, and so on Question 1: I want to use LINQ to find avg sq. km of land per country Eg: Canada - 2459 UK - 3243 US - 3564

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• Get other classes from an element with Jquery

  - by Jigs

  I am working on a small bit of script that will allow for easy and flexible creation of buttons. My buttons are made of three parts, a left, a right and a streched middle piece. There are three different sizes and three different colours of each. I have written the code that resizes the button to fit the text. Now I am looking to add the ability to easily set the colour and size. I was thinking of using three classes something like <div class="button blue big"> My script already loops through the button classes using each. Now I need to find out what other classes are set and adjust the pictures and dimentions used to fit. So how can I find out what other class selectors an element has? Also I am fairly new to jquery/javascript so I am wondering if storing the design as class selectors is the best way.

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• How are value types implemented in .NET

  - by Michael

  Been looking around the net and can't find any articles about how value types are actually implemented. For instance, an Int32 is a struct and it's direct parent is System.ValueType and that's ultimate parent is System.Object. Object is a class - I imagine ValueType is a class? What's the class hierarchy? What part does the CLR have to play? At what stage and how does the CLR know to allocate value types to the stack? (FYI, I am aware that value types are stored where they are declared).

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• Can I join 2+ styles together into a superstyle?

  - by Kurru

  Hi I was looking to join 2 styles together to make a super style for easy use and customisation of my page. Is it possible to define something like this? (if so how) .bold { font-weight: bold;} .color1 {color: white;} .boldColor {.bold; .color1;} where .boldColor is effectively .boldColor {font-weight:bold; color:white;} I want this so that I can have styles thoughout the page and be able to easily change the colors in many places in 1 place. I'm currently using <p class="bold color"> but some of my class defs are becoming long so I'd like to be able to use <p class="boldColor"> Thanks

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• mx.core::BitmapAsset could not be found

  - by asksuperuser

  I tried the code EmbedAssets.as below found in sample here: http://www.senocular.com/flash/tutorials/as3withmxmlc/ I got this error when building with mxmlc.exe and testing the ouput EmbedAssets.swf in Flash Player 9: VerifyError: Error #1014: mx.core::BitmapAsset could not be found package { import flash.display.Sprite; public class EmbedAssets extends Sprite { [Embed(source="images/trophy.png")] private var TrophyImage:Class; [Embed(source="swfs/satdish.swf")] private var SatelliteAnimation:Class; public function EmbedAssets() { addChild(new SatelliteAnimation()); addChild(new TrophyImage()); } } } satdish.swf is not corrupted so I don't understand why this error message.

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• Inheritance: possible to change base reference to something else?

  - by fred

  For example I have two classes, Base and Derived as shown below: class Base { public string Name { get; set; } public Base() { } } class Derived : Base { public Derived(Base b) { base = b; // doesn't compile, but is there any way to do something similar? } } So that they behave like this: Base b = new Base(); b.Name = "Bob"; Derived d = new Derived(b); d.Name = "John"; // b.Name is now "John" also Is this possible? I guess one way would be to keep the Base b reference in Derived and override Derived.Name to point to b.Name? Is there an easier way though, for example if I have like 50 properties to override? class Derived : Base { Base b; public override string Name { get { return b.Name; } set { b.Name = value; } } public Derived(Base b) { this.b = b; } }

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• problem with update the counter value

  - by Edan

  Hello, I having problem to update the counter (integer value). this is the definitions of the class: public class Item_Actions { private final int MAX_ITEMS = 100; private Item myItem[]; private int counter; public Item_Actions() { myItem = new Item[MAX_ITEMS]; counter++; } //Constructor add item into the menu (Description, type & price of Item) public void addItem(Item itm) { myItem[counter] = itm; counter++; }....... Now everytime I call the addItem constructor from another class, the counter always stays on zero. What causing it and how do I save the data inside? thanks

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• GetValue on static field inside nested classes.

  - by Sir Gallahad

  Hi... I have the following class declared. I need to retreive the class structure and the static values without instanciate it. public MyClass() { public static string field = "Value"; public nestedClass() { public static string nestedField = "NestedValue"; } } I've successfuly used GetFields and GetNestedType to recover the class structure and GetValue(null) works fine on field, but not on nestedField. Let me sample: var fi = typeof(MyClass).GetField("field", BindingFlags.Public | BindingFlags.Static); var nt = typeof(MyClass).GetNestedType("nestedClass", BindingFlags.Public); var nfi = nt.GetField("nestedField", BindingFlags.Public | BindingFlags.Static); // All the above references are detected correctly var value = fi.GetValue(null); // until here everything works fine. value == "Value" var nestedValue = nfi.GetValue(null); // this one does not work!! Anyone knows why the last line does not work and how to work around? Thanks.

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• How to get a collection of divs with jquery?

  - by Gal Miller

  I want to get the second img: <form id="formElem" name="formElem" action="" method="post"> <fieldset class="step"> <img src="1.jpg" > </fieldset> <fieldset class="step"> <img src="2.jpg" > </fieldset> <fieldset class="step"> <img src="3.jpg" > </fieldset> </form> I tried doing something like: var imgSRC = $("div[id ='step']").get(1).find('img').attr('src'); alert(imgSRC); Got nothing....

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• Beginner questions regarding Python classes.

  - by Andy

  Hi. I am new to Python so please don't flame me if I ask something too noobish :) 1. Consider I have a class: class Test: def __init__(self, x, y): self.x = x self.y = y def wow(): print 5 * 5 Now I try to create an object of the class: x = Test(3, 4) This works as expected. However, when I try to call the method wow(), it returns an error, which is fixed by changing wow() to: def wow(self) Why do I need to include self and if I don't, what does the method mean?2. In the definition of __init__: def __init__(self, x, y): self.x = x self.y = y Why do I need to declare x and y, when I can do this: def __init__(self): self.x = x self.y = y I hope I am being clear... Thanks for your time.

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• Copying pointers in C++

  - by tunnuz

  Hello, I have a class A containing two pointers to objects of another class B. I want to initialize one pointer or the other depending on which one is passed to init(), which also takes other parameters. My situation is thus the following: class A { public: A(); init(int parameter, int otherParameter, B* toBeInitialized); protected: B* myB; B* myOtherB; }; Now my point is that I want to call init() as: init(640, 480, this->myB); or init(640, 480, this->myOtherB); Now, my init is implemented as: void init( int parameter, int otherParameter, B* toBeInitialized ) { toBeInitialized = someConstructorFunction(parameter, otherParameter); } The problem is that the two pointers are not initialized, I suspect that toBeInitialized is overwritten, but the original parameter is not modified. I am doing something wrong? Should I use references to pointers? Thank you Tommaso

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• How can I update only certain fields in a Django model form?

  - by J. Frankenstein

  I have a model form that I use to update a model. class Turtle(models.Model): name = models.CharField(max_length=50, blank=False) description = models.TextField(blank=True) class TurtleForm(forms.ModelForm): class Meta: model = Turtle Sometimes I don't need to update the entire model, but only want to update one of the fields. So when I POST the form only has information for the description. When I do that the model never saves because it thinks that the name is being blanked out while my intent is that the name not change and just be used from the model. turtle_form = TurtleForm(request.POST, instance=object) if turtle_form.is_valid(): turtle_form.save() Is there any way to make this happen? Thanks!

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• how XSLT convert tag inside tag?

  - by cc96ai

  I have the following XML <title> This is a <highlight>test</highlight> thanks. </title> and want to convert into <span class="title">this is a <span class="highlight">test</span> thanks.</span> I try this xslt, only can ge the text inside title tag, how can I also convert the highlight tag? <span class="title"><xsl:value-of select="title"/></span>

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• Beginning with Datampper, Association question

  - by Ian

  I'm just diving into Datamapper (and Sinatra) and have a question about associations. Below are some models I have. This is what I want to implemented. I'm having an issue with Workoutitems and Workout. Workout will be managed separately, but Workoutitems has a single workout associated with each row. Workout - just a list of types of workouts (run, lift, situps, etc) Selected workout - this is the name of a set of workouts, along with notes by the user and trainer. It has a collection of N workoutitems Workoutitems - this takes a workout and a number of repetitions to it that go in the workout set. class Workout include DataMapper::Resource property :id, Serial #PK id property :name, String, :length=50,:required=true # workout name property :description, String, :length=255 #workout description end class Selectedworkout include DataMapper::Resource property :id, Serial property :name, String, :length=50, :required=true property :workout_time, String, :length=20 property :user_notes, String, :length=255 property :coach_notes, String, :length=255 has n, :workoutitems end class Workoutitem include DataMapper::Resource property :id, Serial property :reps, String, :length=50, :required=true belongs_to :selectedworkout end

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• Objective C - Custom Getter with inheritance

  - by anhdat

  Recently I have worked with Core Data. When I want to set a default value for some fields, I came up with this problem: So I made a simple represent: We have 2 class Parent and Child, in which Child inherit from Parent. // Parent.h @interface Parent : NSObject @property (strong, nonatomic) NSString *lastName; // Child.h @interface Child : Parent In Parent class, I made a custom getter to set a default value when nothing is set: // Parent.h - (NSString *)lastName { if (_lastName) { return _lastName; } else { return @"Parent Default Name"; } } But I cannot make a custom default value for the field "name" which Child inherits from its Parent. // Child.h @implementation Child - (NSString *)lastname { if (super.lastName) { return super.lastName; } else { return @"Child Default Name"; } } Apparently, this method is never called. So my question here is: How can I set a custom getter for the field the Child class inherits from Parent without define an overriding property?

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• How do I supply values to an referenced assembly without calling a method it explicitly?

  - by Rob

  Currently I have a static class that I use as my logging module. I’ve added the class to my visual studio solution. Within the class I’ve specified the name and location of the log file to use. Which lets me do stuff like this – which I like and want. Logger.Information(“Page_Load”,”controls loaded correctly”); I’d like to refactor the code and move the logging functionality into a separately compiled assembly, if I did this I would then need to pass in the log file name and location to save the files too. However I don’t want to have to supply this information every time I call the ‘Logging’ method, this would be bad... Logger.Informtaion(“Page_Load”,”controls loaded correctly”,”logfile.txt”,”c:\temp”); Is there any way I can supply this information without having to specify it within each page or via the method call.

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• [app-engine-java-groovy] One-to-Many relationship. Select objects from datastore.

  - by Olexandr

  Hi. I've omitted some code(package declarations, imports, other fields) for shortness. I have here simple One-to-Many relation. It worked fine till this moment. @PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true") class Restaurant implements Serializable { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) Key id @Persistent(mappedBy = "restaurant") List<RestaurantAddress> addresses = new ArrayList<RestaurantAddress>() } //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= @PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true") class RestaurantAddress implements Serializable { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) Key id @Persistent Restaurant restaurant } Now i need to get(select) all the Restaurants from DB: def getRestaurantsToExport(final String dst, final int count) { String field = restaurantExportFields[dst] return transactionExecute() { PersistenceManager pm -> Query q = pm.newQuery(Restaurant.class) q.filter = "$field == null" q.setRange(0, count) return q.execute() } } But there are on problem - query gives me 12 restaurants(as in DB) but every Restaurant has 0 Address but in Datastore every Restaurant has minimum 2 addresses. Have anyone the same problem or knows the solution ?

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