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  • What is a truly empty std::vector in C++?

    - by RyanG
    I've got a two vectors in class A that contain other class objects B and C. I know exactly how many elements these vectors are supposed to hold at maximum. In the initializer list of class A's constructor, I initialize these vectors to their max sizes (constants). If I understand this correctly, I now have a vector of objects of class B that have been initialized using their default constructor. Right? When I wrote this code, I thought this was the only way to deal with things. However, I've since learned about std::vector.reserve() and I'd like to achieve something different. I'd like to allocate memory for these vectors to grow as large as possible because adding to them is controlled by user-input, so I don't want frequent resizings. However, I iterate through this vector many, many times per second and I only currently work on objects I've flagged as "active". To have to check a boolean member of class B/C on ever iteration is silly. I don't want these objects to even BE there for my iterators to see when I run through this list. Is reserving the max space ahead of time and using push_back to add a new object to the vector a solution to this?

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  • How to check if TypeIdenitifier(T) is an Object?

    - by John
    I'm creating a generic list class that has a member of type Array(Array of ). The problem is the class descruction,because the class is supposed to be used for types from byte to types inheriting TObject. Specifically: destructor Destroy; var elem:T; begin /*if(T is Tobject) then //Check if T inherits TObject {Compiler error!} for elem in FData do TObject(elem).Free;*/ // do not know how to do it SetLength(FItems,0); //FItems : Array of T inherited Destroy; end; How do I check if T is TObject so I can free every member if the typeidenitifier is a class,for example?

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  • Conditional on WebClient

    - by CarryFlag
    Given: thin client (JS) model services client use services. services use model. Model consists of (for sample): Rect Circle ... Ellipse services: class CanvasProviger { public Canvas getCanvas() { return new Canvas(); } } model: class Canvas ... { private List < Figure > figures = new List < Figure >; ... } class Circle extends Figure { private int x, y, r; } class Rect extends Figure { private x, y, w, h; } client: ... var figure = MyJSRPCImpl.getCanvas().nextFigure(); if(figure == JSLocalModel.Rect) { drawRect(figure); } else if(figure == JSLocalModel.Circle) { drawCircle(figure); } ... How else can do way conditional? In rich client I used pattern Visitor. // my bad english, I know =(

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  • Integration testing - can it be done right?

    - by Max
    I used TDD as a development style on some projects in the past two years, but I always get stuck on the same point: how can I test the integration of the various parts of my program? What I am currently doing is writing a testcase per class (this is my rule of thumb: a "unit" is a class, and each class has one or more testcases). I try to resolve dependencies by using mocks and stubs and this works really well as each class can be tested independently. After some coding, all important classes are tested. I then "wire" them together using an IoC container. And here I am stuck: How to test if the wiring was successfull and the objects interact the way I want? An example: Think of a web application. There is a controller class which takes an array of ids, uses a repository to fetch the records based on these ids and then iterates over the records and writes them as a string to an outfile. To make it simple, there would be three classes: Controller, Repository, OutfileWriter. Each of them is tested in isolation. What I would do in order to test the "real" application: making the http request (either manually or automated) with some ids from the database and then look in the filesystem if the file was written. Of course this process could be automated, but still: doesn´t that duplicate the test-logic? Is this what is called an "integration test"? In a book i recently read about Unit Testing it seemed to me that integration testing was more of an anti-pattern?

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  • PyQt4 plugin in c++ application

    - by veverica17
    How is it posible to load python script as plugin in qt based application? The basic idea would be to make a class in c++ class b { virtual void method1(); virtual void method2(); } and 'somehow' inherit it in python like class c(b): def method1: #do something def method2: #do something I need to be able to modify the gui from python( add buttons to some widgets made in c++ with qt ). Basicaly something similiar to (gedit, blender, etc) plugin architecture with qt

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  • Django - Problem with models/manager to organise a query...

    - by user296644
    Hi, I have an application to count the number of access to an object for each website in a same database. class SimpleHit(models.Model): """ Hit is the hit counter of a given object """ content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type', 'object_id') site = models.ForeignKey(Site) hits_total = models.PositiveIntegerField(default=0, blank=True) [...] class SimpleHitManager(models.Manager): def get_query_set(self): print self.model._meta.fields qset = super(SimpleHitManager, self).get_query_set() qset = qset.filter(hits__site=settings.SITE_ID) return qset class SimpleHitBase(models.Model): hits = generic.GenericRelation(SimpleHit) objects = SimpleHitManager() _hits = None def _db_get_hits(self, only=None): if self._hits == None: try: self._hits = self.hits.get(site=settings.SITE_ID) except SimpleHit.DoesNotExist: self._hits = SimpleHit() return self._hits @property def hits_total(self): return self._db_get_hits().hits_total [...] class Meta: abstract = True And I have a model like: class Model(SimpleHitBase): name = models.CharField(max_length=255) url = models.CharField(max_length=255) rss = models.CharField(max_length=255) creation = AutoNowAddDateTimeField() update = AutoNowDateTimeField() So, my problem is this one: when I call Model.objects.all(), I would like to have one request for the SQL (not two). In this case: one for Model in order to have information and one for the hits in order to have the counter (hits_total). This is because I cannot call directly hits.hits_total (due to SITE_ID?). I have tried select_related, but it seems to do not work... Question: - How can I add column automatically like (SELECT hits.hits_total, model.* FROM [...]) to the queryset? - Or use a functional select_related with my models? I want this model could be plugable on all other existing model. Thank you, Best regards.

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  • Strange C++ thread function invocation

    - by Tony
    I have the following: class DThread { virtual void run()=0; _beginthreadex(NULL,0,tfunc,this,0,&m_UIThreadID); // class itself being passed as param to thread function... static unsigned int __stdcall tfunc(void* thisptr) { static_cast<DThread*>(thisptr)->run(); return 0; } //other stuff } The run function is implemented in a derived class. Why is the function that's being called in the thread being called through a cast this pointer? Is this good practise? Can't it just be called directly? The actual function needing to run is in the derived class. My question is

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  • How do I write a Guice Provider that doesn't explicitly create objects?

    - by ripper234
    Say I have a ClassWithManyDependencies. I want to write a Guice Provider for this class, in order to create a fresh instance of the class several times in my program (another class will depend on this Provider and use it at several points to create new instances). One way to achieve this is by having the Provider depend on all the dependencies of ClassWithManyDependencies. This is quite ugly. Is there a better way to achieve this? Note - I certainly don't want the Provider to depend on the injector. Another option I considered is having ClassWithManyDependencies and ClassWithManyDependenciesProvider extend the same base class, but it's butt ugly.

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  • Should I denormalize a has_many has_many?

    - by Cameron
    I have this: class User < ActiveRecord::Base has_many :serials has_many :sites, :through => :series end class Serial < ActiveRecord::Base belongs_to :user belongs_to :site has_many :episodes end class Site < ActiveRecord::Base has_many :serials has_many :users, :through => :serials end class Episode < ActiveRecord::Base belongs_to :serial end I would like to do some operations on User.serials.episodes but I know this would mean all sorts of clever tricks. I could in theory just put all the episode data into serial (denormalize) and then group_by Site when needed. If I have a lot of episodes that I need to query on would this be a bad idea? thanks

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  • Tracking changed (unsaved) objects

    - by Eric
    I have a class which is serialized to and from an XML file when the user decided to open or save. I'm trying to add the typical functionality where when they try to close the form with un-saved changes the form warns them and gives them the option of saving before closing. I've added a HasUnsavedChanges property to my class, which my form checks before closing. However, it's a little annoying that my properties have changed from something like this .. public string Name { get; set; } to this... private string _Name; public string Name { get { return _Name; } set { this._Name = value; this.HasUnsavedChanges = true; } } Is there a better way to track changes to an instance of a class? For example is there some standard way I can "hash" an instance of a class into a value that I can use to compare the most recent version with the saved version without mucking up every property in the class?

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  • Is there a way to get the current UIEvent being handled?

    - by not-
    I'm working in a class that is a delegate of another class; this other class is in a third-party library that I'd like to avoid changing if at all possible. The original class is handling a -touchesEnded event, and is delegating responsibility to me, but it doesn't pass the UIEvent itself to me. Is there a way to get a handle to the current event in progress? It's a double-tap handler, and all that is passed to me is the view being touched, and the point at which the touch occurred. I want to know exactly how many touches are involved in the event. Thanks! randy

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  • Avoiding sub-type selection in view code

    - by John Donoghue
    Hi, I have some code where the model contains some classes like (vb.net pseudocode, but could be any OO language): Enum AttributeType Boolean Date String End Enum MustInherit Class Attibute Must Override Function Type As AttributeType End Class Class BooleanAttribute: Attribute Function Type As AttributeType Return AttributeType.Boolean End Function End Class And the view contains some code like: Select Case AttributeType Case Boolean //Display checkbox control Case Date //Display date picker control Case String //Display textbox control End Select I don't really like the code in the view, for the hopefully obvious reasons (what happens when I get a new attribute type etc). My question is, how should I replace it? I could easily add a method to the concrete classes, but that pollutes the model with UI stuff so that's a horrible idea. I could move the select into a factory, but that seems to be just hiding the problem. Can anybody advise a better approach?

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  • Why does Java think my object is a variable?

    - by user2896898
    Ok so I'm trying to make a simple pong game. I have a paddle that follows the mouse and a ball that bounces around. I wrote a method collidesWith(Sprite s) inside of my Sprite class that checks if the ball collides with the paddle (this works and isn't the problem). I have two objects extending my sprite class, a ball and a paddle object. So inside of my ball class I'm trying to check if it collides with the paddle. So I've tried if(this.collidesWith(paddle) == true){ System.out.println("They touched"); } I've also tried ball.collidesWith(paddle) and other combinations but it always says the same thing about the paddle (and the ball when I use ball.collidesWith) "Cannot find symbol. Symbol: variable paddle(or ball). Location: class Ball" So if I'm reading this right, it thinks that the paddle (and ball) are variables and it's complaining because it can't find them. How can I make it understand I am passing in objects, not variables? For extra information, an earlier assignment had me make two boxes and for them to change colors when they were colliding. In that assignment I used very similar code to above with if(boxOne.collidesWith(boxTwo) == true){ System.out.println("yes"); } And in this code it worked just fine. The program knew that boxOne and boxTwo were child classes of my Sprite class. Anyone know why they wouldn't work the same?

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  • jQuery Reference First Column in HTML Table

    - by Vic
    I have a table where all of the cells are INPUT tags. I have a function which looks for the first input cell and replaces it with it's value. So this: <tr id="row_0" class="datarow"> <td><input class="tabcell" value="Injuries"></td> <td><input class="tabcell" value="01"></td> becomes this: <tr id="row_0" class="datarow"> <td>Injuries</td> <td><input class="tabcell" value="01"></td> Here is the first part of the function: function setRowLabels() { var row = []; $('.dataRow').each(function(i) { row.push($('td input:eq(0)', this).val() + ' - '); $('td input:eq(0)', this).replaceWith($('td input:eq(0)', this).val()); $('td input:gt(0)', this).each(function(e) { etcetera But when the page reloads, the first column is not an input type, so it changes the second column to text too! Can I tell it to only change the first column, no matter what the type is? I tried $('td:eq(0)', this).replaceWith($('td:eq(0)', this).val()); but it does not work. Any suggestions appreciated! Thanks

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  • Running a groovy script created in STS(Spring Tool Suite) using the command line

    - by user1811107
    I have used the STS(Spring Tool Suite) to create a compiled groovy script which exists as a file on windows called Test.class. I am able to right click on the file in STS and execute it which works well. However - I want to be able to execute the script on the windows command line, so far I have tried various ways but have not been successful. I have tried the following... java -cp C:\Users\MyName\springsource\sts- 3.1.0.RELEASE\plugins\org.codehaus.grails.bundle_2.1.1\content\lib\ org.codehaus.groovy\groovy-all\jars\groovy-all-1.8.8.jar Test.class But that does not work it gives me an error -- Error: Could not find or load main class Test.class Any Pointers?

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  • Overriding inherited generic methods

    - by jess
    I have this code in base class protected virtual bool HasAnyStuff<TObject>(TObject obj) where TObject:class { return false; } In child class I am overriding protected override bool HasAnyStuff<Customer>(Customer obj) { //some stuff if Customer.sth etc return false; } I am getting this error '''Type parameter declaration must be an identifier not a type''' What is it I am doing wrong here?

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  • PHP: constant as variable in function

    - by m4recek
    I'm trying to use constant as a function paramter, is it possible to check type of this constant. Example of what I want: class ApiError { const INVALID_REQUEST = 200; } class Response { public function status(ApiError $status) { //function code here } } USE: $response = new Response(); $response->status(ApiError::INVALID_REQUEST); This shoud check that given $status is constant of class ApiError. Is something like this possible?

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  • C++: Is there a way to limit access to certain methods to certain classes without exposing other pri

    - by dadads
    I have a class with a protected method Zig::punt() and I only want it to be accessible to the class "Avocado". In C++, you'll normally do this using the "friend Avocado" specifier, but this will cause all of the other variables to become accessible to "Avocado" class; I don't want this because this breaks encapsulation. Is what I want impossible, or does there already exist an obscure trick out there that I can use to achieve what I want? Or possibly alternative class design patterns that'll achieve the same thing? Thanks in advance for any ideas!

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  • Rails: bi-directional has_many :through relationship

    - by Chris
    I have three models in a Rails application: Game represents an instance of a game being played. Player represents an instance of a participant in a game. User represents a registered person who can participate in games. Each Game can have many Players, and each User can have many Players (a single person can participate in multiple games at once); but each Player is in precisely one Game, and represents precisely one User. Hence, my relationships are as follows at present. class Game has_many :players end class User has_many :players end class Player belongs_to :game belongs_to :user end ... where naturally the players table has game_id and user_id columns, but games and users have no foreign keys. I would also like to represent the fact that each Game has many Users playing in it; and each User has many Games in which they are playing. How do I do this? Is it enough to add class Game has_many :users, :through => :players end class User has_many :games, :through => :players end

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  • [C#] How do I make hierarchy of objects from two alternating classes?

    - by Millicent
    Here's the scenario: I have two classes ("Page" and "Field"), that are descended from a common class ("Pield"). They represent tags in an XML file and are in the following hierarchy: <page> <field> <page> ... </page> ... </field> ... </page> I.e.: Page and Field objects are in a hierarchy of alternating type (there may be more than one Page or Field to each rung of the hierarchy). Every Field and Page object has a parent property, which points to the respective parent object of the other type. This is not a problem unless the parent-child mechanism is controlled by the base class (Pield), which is shared by the two descended classes (Page and Field). Here is one try, that fails at the line "Pield child = new Pield(pchild, this);": class Pield<T> { private T _pield_parent; ... private void get_children() { ... Pield<Page> child = new Pield<Page>(pchild, this); ... } ... } class Page : Pield<Field> { ... } class Field : Pield<Page> { ... } Any ideas about how to solve this elegantly? Best, Millicent

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  • Minimal framework in Scala for collections with inheriting return type

    - by Rex Kerr
    Suppose one wants to build a novel generic class, Novel[A]. This class will contain lots of useful methods--perhaps it is a type of collection--and therefore you want to subclass it. But you want the methods to return the type of the subclass, not the original type. In Scala 2.8, what is the minimal amount of work one has to do so that methods of that class will return the relevant subclass, not the original? For example, class Novel[A] /* What goes here? */ { /* Must you have stuff here? */ def reverse/* What goes here instead of :Novel[A]? */ = //... def revrev/*?*/ = reverse.reverse } class ShortStory[A] extends Novel[A] /* What goes here? */ { override def reverse: /*?*/ = //... } val ss = new ShortStory[String] val ss2 = ss.revrev // Type had better be ShortStory[String], not Novel[String] Does this minimal amount change if you want Novel to be covariant? (The 2.8 collections do this among other things, but they also play with return types in more fancy (and useful) ways--the question is how little framework one can get away with if one only wants this subtypes-always-return-subtypes feature.)

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  • Problem using a costum server control in a aspx

    - by gre3ns0ul
    Hi guys, i am having a issue. I already developed one class (my custom gridview) and i want use it on a .aspx That class is defined in app_code and compiled to the dll of the project. namespace MyCostumControls{  public class DropDownPagingGridView : GridView{ ... I already registered the control on the aspx page using <%@ Register Namespace="MyCostumControls" TagPrefix="ctrl" % and i can use in the page and works ok.. But i'm watching one problem. That class contains methods defined by me, than when i try to call them in code-behind sayd to me than they're not defined. In designed i don't see the reference to MyCostumControls, and when i try declare one field using protected global::MyCostumControls.MyCostumControls ddl_gv_errors, i cannot access to MyCostumControls namespace, Is because he's compiled to the project dll? I can access to all namespaces than are not contained in app_code. Solutions? Apreciate. Thanks

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  • [Ruby On Rails] belongs_to with :class_name option fails.

    - by crackpot
    I have no idea what went wrong but I can't get belongs_to work with :class_name option. Could somebody enlighten me. Thanks a lot! Here is a snip from my code. class CreateUsers < ActiveRecord::Migration def self.up create_table :users do |t| t.text :name end end def self.down drop_table :users end end ##################################################### class CreateBooks < ActiveRecord::Migration def self.up create_table :books do |t| t.text :title t.integer :author_id, :null => false end end def self.down drop_table :books end end ##################################################### class User < ActiveRecord::Base has_many: books end ##################################################### class Book < ActiveRecord::Base belongs_to :author, :class_name => 'User', :validate => true end ##################################################### class BooksController < ApplicationController def create user = User.new({:name => 'John Woo'}) user.save @failed_book = Book.new({:title => 'Failed!', :author => @user}) @failed_book.save # missing author_id @success_book = Book.new({:title => 'Nice day', :author_id => @user.id}) @success_book.save # no error! end end environment: ruby 1.9.1-p387 Rails 2.3.5

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