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  • Problem overridding virtual function

    - by William
    Okay, I'm writing a game that has a vector of a pairent class (enemy) that s going to be filled with children classes (goomba, koopa, boss1) and I need to make it so when I call update it calls the childclasses respective update. I have managed to create a example of my problem. #include <stdio.h> class A{ public: virtual void print(){printf("Hello from A");} }; class B : public A{ public: void print(){printf("Hello from B");} }; int main(){ A ab = B(); ab.print(); while(true){} } Output wanted: "Hello from B" Output got: "Hello from A" How do I get it to call B's print function?

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  • Dynamically load a type from an external assembly

    - by Water Cooler v2
    From managed code, how do I load a managed type from another assembly at runtime, assuming the calling code does not have a static reference to the assembly? To clarify, let's say I have class Lib in Lib.cs compiled into Lib.dll. I want to write a class Foo in a separate assembly called Foo.dll, that does not have a reference to Lib.dll statically, but instead loads Lib.dll and then reflects on for the presence of the class Lib and then calls a method on it. Sorry for such an obvious question on Reflection. I figure it'll take much lesser time to get the answer on a forum that to read a few articles.

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  • django form creation on init

    - by John
    Hi, How can I add a field in the form init function? e.g. in the code below I want to add a profile field. class StaffForm(forms.ModelForm): def __init__(self, user, *args, **kwargs): if user.pk == 1: self.fields['profile'] = forms.CharField(max_length=200) super(StaffForm, self).__init__(*args, **kwargs) class Meta: model = Staff I know I can add it just below the class StaffForm.... line but I want this to be dynamic depending on what user is passed in so can't do it this way. Thanks

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  • syntax error, unexpected '.', expecting ')'

    - by Jonathan
    Hi, I've got a problem when I'm calling a static var from another class. I get this pretty syntax error where php is unexpected the '.' Here is where I'm calling it : private $aLien = array( "menu1" => array("Accueil","statique/".Variable_init::$langue."/accueil.html",0,0), //This line "menu2" => array("Infos Pratiques","statique/".Variable_init::$langue."/info.html",0,0), "menu3" => array("Faire une réservation","statique/".Variable_init::$langue."/reserver.html",0,0), "menu4" => array("Pour Nous Joindre","statique/".Variable_init::$langue."/nousJoindre.html",0,0), "menu5" => array("Plan du site","statique/".Variable_init::$langue."/plansite.html",0,0) ); And here is my static var declaration from another class: class Variable_init implements iVariable_init{ public static $langue; public static $id_choix; public static $id_contenu;

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  • How to get global access to enum types in C#?

    - by lala
    This is probably a stupid question, but I can't seem to do it. I want to set up some enums in one class like this: public enum Direction { north, east, south, west }; Then have that enum type accessible to all classes so that some other class could for instance have: Direction dir = north; and be able to pass the enum type between classes: public void changeDirection(Direction direction) { dir = direction; } I thought that setting the enum to public would make this automatically possible, but it doesn't seem to be visible outside of the class I declared the enum in.

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  • What is this Design Pattern?

    - by Can't Tell
    I read the Wikipedia articles on FactoryMethod and AbstractFactory but the following code doesn't seem to fit anywhere. Can someone explain to me what the following pattern is or if it is an anti-pattern? interace PaymentGateway{ void makePayment(); } class PaypalPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class AuthorizeNetPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class PaymentGatewayFacotry{ PaymentGateway createPaymentGateway(int gatewayId) { if(gatewayId == 1) return PaypalPaymentGateway(); else if(gatewayId == 2) return AuthorizeNetPaymentGateway(); } } Let's say the user selects the payment method using a radio button on an html page and the gatewayId is derived from the radio button value. I have seen code like this and thought it was the AbstractFactory pattern but after reading the Wikipedia article, I'm having doubts.

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  • When is it safe to do a Response.Redirect() without throwing an exception?

    - by DDechant
    I have an intermediary class extending System.Web.UI.Page for all of my pages that require authentication. The class mostly does custom authentication handling. When a user with insufficient access attempts to visit a page, I try to redirect the user back to the login page while preventing any further page events from being executed (ie. Page_load). The first solution that came to mind was the default implementation of Response.Redirect. Of course the downside to this is the possibility of ThreadAbortExceptions being thrown. So my question is this: When (if at all) during the page life cycle is it actually safe to execute Response.Redirect() without ThreadAbortException ever being thrown? public class CustomPage : System.Web.UI.Page { protected override void OnInit(EventArgs e) { base.OnInit(e); if (!IsValid()) Response.Redirect("login.aspx", true); } }

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  • static const double in c++

    - by Crystal
    Is this the proper way to use a static const variable? In my top level class (Shape) #ifndef SHAPE_H #define SHAPE_H class Shape { public: static const double pi; private: double originX; double originY; }; const double Shape::pi = 3.14159265; #endif And then later in a class that extends Shape, I use Shape::pi. I get a linker error. I moved the const double Shape::pi = 3.14... to the Shape.cpp file and my program then compiles. Why does that happen? thanks.

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  • Can I write functors using a private nested struct?

    - by Kristo
    Given this class: class C { private: struct Foo { int key1, key2, value; }; std::vector<Foo> fooList; }; The idea here is that fooList can be indexed by either key1 or key2 of the Foo struct. I'm trying to write functors to pass to std::find so I can look up items in fooList by each key. But I can't get them to compile because Foo is private within the class (it's not part of C's interface). Is there a way to do this without exposing Foo to the rest of the world? (note: I've got to run to a meeting. I'll be able to post more sample code in about a half hour.)

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  • C++ memory management of reference types

    - by Russel
    Hello, I'm still a fairly novice programmer and I have a question about c++ memory management with refence types. First of all, my understanding of reference types: A pointer is put on the stack and the actual data that the pointer points to is created and placed on the heap. Standard arrays and user defined classes are refence types. Is this correct? Second, my main question is do c and c++'s memory management mechanisms (malloc, free and new, delete) always handle this properly and free the memory that a class or array is pointing to? Does everything still work if those pointers get reassigned somehow to other objects of the same size/type on the heap? What if a class has a pointer member that points to another object? I am assuming that delete/freeing the class object doesn't free what it's member pointer points to, is that correct? Thanks all! -R

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  • Best way to test instance methods without running __init__

    - by KenFar
    I've got a simple class that gets most of its arguments via init, which also runs a variety of private methods that do most of the work. Output is available either through access to object variables or public methods. Here's the problem - I'd like my unittest framework to directly call the private methods called by init with different data - without going through init. What's the best way to do this? So far, I've been refactoring these classes so that init does less and data is passed in separately. This makes testing easy, but I think the usability of the class suffers a little. EDIT: Example solution based on Ignacio's answer: import types class C(object): def __init__(self, number): new_number = self._foo(number) self._bar(new_number) def _foo(self, number): return number * 2 def _bar(self, number): print number * 10 #--- normal execution - should print 160: ------- MyC = C(8) #--- testing execution - should print 80 -------- MyC = object.__new__(C) MyC._bar(8)

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  • In c++ is there any Events/delegates/interfaces/notifications! anything?

    - by Bach
    Say i have these classes ViewA and ViewB In objective C using the delegate pattern I could do @protocol ViewBDelegate{ - (void) doSomething(); } then in ViewB interface: id<ViewBDelegate> delegate; then in ViewA implementation i set the delegate: viewB.delegate = self; and now I can call in doSomething from viewB onto any that unknown type delegate. [delegate doSomething]; "C++ How to Program" has been the worse read an can't find simple examples that demonstrates basic design patterns. What i'm looking for in C++ is: events ActionScript and java either delegates or notifications in Objective C anything that allows class A, Class B and Class C to know that ClassX didSomething()!!! thanks

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  • Where is BuildConfig.DEBUG?

    - by Ollie C
    My project doesn't seem to be aware of this new constant that's apparently auto-generated in Android Tools r17 builds: "Added a feature that allows you to run some code only in debug mode. Builds now generate a class called BuildConfig containing a DEBUG constant that is automatically set according to your build type. You can check the (BuildConfig.DEBUG) constant in your code to run debug-only functions such as outputting debug logs." I've confirmed that this class is not being auto-generated anywhere in my project by the new tools. I deleted all project outputs (including all gen folders) and rebuilt, and only R.java classes are being generated. Why are the tools not generating the BuildConfig class? It may be relevant that I'm using IntelliJ.

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  • Jsf validation error (shown by h:message) while updating Model, why?

    - by Ignacio
    List.xhtml: <h:selectOneMenu value="#{produtosController.selected.codigo}"> <f:selectItems value="#{produtosController.itemsAvailableSelectOne}"/> </h:selectOneMenu> <h:commandButton action="#{produtosController.createByCodigos}" value="Buscar" /> Controller Class method: public String createByCodigos(){ items = new ListDataModel(ejbFacade.findByCodigos(current.getCodigo())); updateCurrentItem(); return "List"; } Facade Class method: public List<Produtos> findByCodigos(Integer codigo){ Query q = em.createNamedQuery("Produtos.findByCodigo"); q.setParameter("codigo", codigo); return q.getResultList(); } Bean Class query: @NamedQuery(name = "Produtos.findByCodigo", query = "SELECT p FROM Produtos p WHERE p.codigo = :codigo") @Column(name = "codigo") private Integer codigo;

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  • has_many relation doesn't seems right or logical, some thing like belongs_to_many looks right

    - by Vijendra
    My situation is like this. Company has many users and users may belongs to many companies. And current implementation is something like below. class Company has_many :employments has_many :users, :through = :employments end class Employment belongs_to :company belongs_to :user end class User has_many :employments has_many :companies, :through = :employments #This doesn't looks correct end User has many companies doesn't looks logically meaningful.It must be some thing like belongs_to_many companies. Do I need to use has_and_belongs_to_many? But that also will gives the same meaning. Can some one please suggest the right way for representing these relationships?

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  • Best indexing strategy for several varchar columns in Postgres

    - by Corey
    I have a table with 10 columns that need to be searchable (the table itself has about 20 columns). So the user will enter query criteria for at least one of the columns but possibly all ten. All non-empty criteria is then put into an AND condition Suppose the user provided non-empty criteria for column1 and column4 and column8 the query would be: select * from the_table where column1 like '%column1_query%' and column4 like '%column4_query%' and column8 like '%column8_query%' So my question is: am I better off creating 1 index with 10 columns? 10 indexes with 1 column each? Or do I need to find out what sets of columns are queried together frequently and create indexes for them (an index on cols 1,4 and 8 in the case above). If my understanding is correct a single index of 10 columns would only work effectively if all 10 columns are in the condition. Open to any suggestions here, additionally the rowcount of the table is only expected to be around 20-30K rows but I want to make sure any and all searches on the table are fast. Thanks!

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  • How do I dynamically add and remove line items from an ASP.NET MVC view?

    - by Mike Roosa
    I have a PurchaseOrder model: public class PurchaseOrder { public string OrderNumber { get; set; } public string Customer { get; set; } public IList<LineItem> Lines { get; set; } } and a LineItem class: public class LineItem { public string PartNumber { get; set; } public int Quantity { get; set; } } What I want to do is on my view for the PurhcaseOrder Create action, I need a section for line items. The user should be able to add a new line, remove a line, then submit. One caveat is the PartNumber needs to be a dropdown list of valid parts. What can I do to accomplish what I'm looking for?

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  • Can I use memcpy in C++ to copy classes that have no pointers or virtual functions

    - by Shane MacLaughlin
    Say I have a class, something like the following; class MyClass { public: MyClass(); int a,b,c; double x,y,z; }; #define PageSize 1000000 MyClass Array1[PageSize],Array2[PageSize]; If my class has not pointers or virtual methods, is it safe to use the following? memcpy(Array1,Array2,PageSize*sizeof(MyClass)); The reason I ask, is that I'm dealing with very large collections of paged data, as decribed here, where performance is critical, and memcpy offers significant performance advantages over iterative assignment. I suspect it should be ok, as the 'this' pointer is an implicit parameter rather than anything stored, but are there any other hidden nasties I should be aware of?

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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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  • having trouble with a mysql query

    - by chuck akers
    this keeps saying Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in directory here the error is near the login_query variable, can someone help me fix it. <?php if (isset($_POST['login_username'], $_POST['login_password'])) { $login_username = trim(mysql_real_escape_string(htmlentities($_POST['login_username']))); $login_password = md5(trim(mysql_real_escape_string(htmlentities($_POST['login_password'])))); if (!empty($login_username) && !empty($login_password)) { $login_query = mysql_query("SELECT user_id FROM username WHERE username='".$login_username."' AND password='".$login_password."'"); if (mysql_num_rows($login_query)==1) { $user_id = mysql_result($login_query, 0, 'user_id'); $_SESSION['user_id'] = $user_id; header('Location: index.php'); die(); } }} ?

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  • How to Add Horizontal line in Javascript

    - by user54197
    I would like to add a horizontal seperating line on a dynamic populated table. How do I do this? Below is a snippet. function addNewRow() { $('#displayTable tr:last').after('<tr><td style="font-size:smaller;" class="dataField1"></td><td style="font-size:smaller;" class="dataField2"></td><td style="font-size:smaller;" class="dataField3"></td></tr>'); var $tr = $('#displayTable tr:last'); $tr.find('.dataField1').text($('#txtName').val()); $tr.find('.dataField2').text($('#txtAddress').val()); $tr.find('.dataField3').text('document.write("<tr><td colspan=\"2\"><hr \/><\/td><\/tr>"); }

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  • Assign values on multi-properties to a object

    - by Lu Lu
    I have a object which it was initialized before in a base class. In inherited class, I use this object and assign values on multi-properties to it. Example: this.Chart.X = 10; this.Chart.Y = 10; this.Chart.Width = 20; this.Chart.Height = 20; this.Chart.Background = Color.Red; However, I must repeat "this.Chart" many times. How to avoid this. Note that I don't want to re-create this object again because in the base class, it was initialized with some common values. Thanks.

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  • RotationAsync with each row in List view

    - by Labeeb P
    Hi, From this answer in stack overflow and the sample project referred there, i got the Idea of RotationAsync, where a progress bar work fine with device rotation. But my problem is, i have a listview with each row there is progress bar. And is there any way to retain the progress while rotation for reach row. Me creating onclicklistener object for the button click listener in getview function of my adapter class. Where its onClick function call the AsyncTask class Since each getview (row) is calling different instant of my AsyncTask, i cannot make it static of single ton class. Any Idea on this. Thanks.

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  • Submtting data using $.ajax and retrieving values from $_POST array

    - by Linda Keating
    I'm having trouble retrieving my form Data that has been submitted via ajax like this: $( "form" ).on( "submit", function( event ) { var formData = $(this).serializeArray(); console.log("fomData"); $.ajax({ url: window.location.origin+ "/selfservicemanager/localtmfsetup/local_tmf_setup.php", type: "POST", data: JSON.stringify(formData), success : function (){ alert("success"); } }); }); I can see the data being sent over the network like this: But when I try to retrieve the data on the server side the $_POST array is empty. <?php var_dump($_POST); die(); ?> array (size=0) empty Any ideas? I've tried to stringify the data being sent, and also tried to decode the $_POST array but it expects a string.....

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  • bulk update/delete entities of different kind in db.run_in_transaction

    - by Ray Yun
    Here goes pseudo code of bulk update/delete entities of different kind in single transaction. Note that Album and Song entities have AlbumGroup as root entity. class AlbumGroup: pass class Album: group = db.ReferenceProperty(reference_class=AlbumGroup,collection_name="albums") class Song: album = db.ReferenceProperty(reference_class=Album,collection_name="songs") def bulk_update_album_group(album_group): updated = [album_group] deleted = [] for album in album_group.albums: updated.append(album) for song in album.songs: if song.is_updated: updated.append(song) if song.is_deleted: deleted.append(song) db.put(updated) db.delete(deleted) a = AlbumGroup.all().filter("...").get() # bulk update/delete album group. for simplicity, album cannot be deleted. db.run_in_transaction(bulk_update_album_group,a) But I met a famous "Only Ancestor Queries in Transactions" error at the iterating reference properties like album.songs or album_group.albums. I guess ancestor() filter does not help because those entities are modified in memory. Should I not to iterate reference property in transaction function and always provide them as function parameters like def bulk_update_album_group(updated,deleted): ??? Is there any good coding pattern for this situation?

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