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  • Assigning a variable of a struct that contains an instance of a class to another variable

    - by xport
    In my understanding, assigning a variable of a struct to another variable of the same type will make a copy. But this rule seems broken as shown on the following figure. Could you explain why this happened? using System; namespace ReferenceInValue { class Inner { public int data; public Inner(int data) { this.data = data; } } struct Outer { public Inner inner; public Outer(int data) { this.inner = new Inner(data); } } class Program { static void Main(string[] args) { Outer p1 = new Outer(1); Outer p2 = p1; Console.WriteLine("p1:{0}, p2:{1}", p1.inner.data, p2.inner.data); p1.inner.data = 2; Console.WriteLine("p1:{0}, p2:{1}", p1.inner.data, p2.inner.data); p2.inner.data = 3; Console.WriteLine("p1:{0}, p2:{1}", p1.inner.data, p2.inner.data); Console.ReadKey(); } } }

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  • Symfony Form render with Self Referenced Entity

    - by benarth
    I have an Entity containing Self-Referenced mapping. class Category { /** * @var integer * * @ORM\Column(name="id", type="integer") * @ORM\Id * @ORM\GeneratedValue(strategy="AUTO") */ private $id; /** * @var string * * @ORM\Column(name="name", type="string", length=100) */ private $name; /** * @ORM\OneToMany(targetEntity="Category", mappedBy="parent") */ private $children; /** * @ORM\ManyToOne(targetEntity="Category", inversedBy="children") * @ORM\JoinColumn(name="parent_id", referencedColumnName="id") */ private $parent; } In my CategoryType I have this : public function buildForm(FormBuilderInterface $builder, array $options) { $plan = $this->plan; $builder->add('name'); $builder->add('parent', 'entity', array( 'class' => 'xxxBundle:Category', 'property' => 'name', 'empty_value' => 'Choose a parent category', 'required' => false, 'query_builder' => function(EntityRepository $er) use ($plan) { return $er->createQueryBuilder('u') ->where('u.plan = :plan') ->setParameter('plan', $plan) ->orderBy('u.id', 'ASC'); }, )); } Actually, when I render the form field Category this is something like Cat1 Cat2 Cat3 Subcat1 Subcat2 Cat4 I would like to know if it's possible and how to display something more like, a kind of a simple tree representation : Cat1 Cat2 Cat3 -- Subcat1 -- Subcat2 Cat4 Regards.

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  • C++ Implicit Conversion Operators

    - by Imbue
    I'm trying to find a nice inheritance solution in C++. I have a Rectangle class and a Square class. The Square class can't publicly inherit from Rectangle, because it cannot completely fulfill the rectangle's requirements. For example, a Rectangle can have it's width and height each set separately, and this of course is impossible with a Square. So, my dilemma. Square obviously will share a lot of code with Rectangle; they are quite similar. For examlpe, if I have a function like: bool IsPointInRectangle(const Rectangle& rect); it should work for a square too. In fact, I have a ton of such functions. So in making my Square class, I figured I would use private inheritance with a publicly accessible Rectangle conversion operator. So my square class looks like: class Square : private Rectangle { public: operator const Rectangle&() const; }; However, when I try to pass a Square to the IsPointInRectangle function, my compiler just complains that "Rectangle is an inaccessible base" in that context. I expect it to notice the Rectangle operator and use that instead. Is what I'm trying to do even possible? If this can't work I'm probably going to refactor part of Rectangle into MutableRectangle class. Thanks.

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  • Most efficient way of checking for a return from a function call in Perl

    - by Gaurav Dadhania
    I want to add the return value from the function call to an array iff something is returned (not by default, i.e. if I have a return statement in the subroutine.) so I'm using unshift @{$errors}, "HashValidator::$vfunction($hashref)"; but this actually adds the string of the function call to the array. I also tried unshift @{$errors}, $temp if defined my $temp = "HashValidator::$vfunction($hashref)"; with the same result. What would a perl one-liner look like that does this efficiently (I know I can do the ugly, multi-line check but I want to learn). Thanks,

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  • How do I add a VSTO project as a reference to a unit testing project?

    - by Mathias
    In order not to pollute my projects with unit tests, I like to create a separate project for my unit tests; I add a reference to the project under test in the unit tests project. However, this isn't working that well with my VSTO excel add-in projects: when I create a separate unit test project and go to Add Reference Projects, there is no project to pick. What I have done so far is Add Reference Browse, and pick the add-in dll from the debug folder. I have also run into issues from time to time with this, with the reference suddenly not working, requiring to remove/re-add the dll reference. Can anybody explain why a VSTO project doesn't show up as a regular project? And is there a better way to go about it than what I am doing presently?

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  • How to add .Net3.5 dll into .Net2.0 project?

    - by macias
    I have a dll which is based on .net 3.5 -- it uses internally for example Linq, but the exposed API is straightforward, no fancy stuff. Since C# generics are resolved at compile time I assume that for calling party all it counts is API (all public parts). However when I try to use this dll from net2.0 project I get info, that the dll cannot be referenced because the dll or one of its dependencies requires a later version of .net framework. I can install any .net version I want on target computer (when entire app is installed), but I cannot change .net version for the project itself. So: how to solve this? When adding a C dll to this project I had no such problems, so are C# dlls self-contained or not?

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  • Does a simple delphi form app needs any libraries or dependencies to deploy?

    - by peterg
    I need to code a simple form application and I want to make it easy to deploy (without installing libraries or dependencies), I don't want to use visual studio cpp or csharp because clr apps compile with .net frameworks and I have no much experience with mfc and dialogs. So I was wondering which libraries does a simple delphi vcl forms app (those using TForm) use, because I've never had to install anything to run simple delphi apps.

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  • Custom string class (C++)

    - by Sanctus2099
    Hey guys. I'm trying to write my own C++ String class for educational and need purposes. The first thing is that I don't know that much about operators and that's why I want to learn them. I started writing my class but when I run it it blocks the program but does not do any crash. Take a look at the following code please before reading further: class CString { private: char* cstr; public: CString(); CString(char* str); CString(CString& str); ~CString(); operator char*(); operator const char*(); CString operator+(const CString& q)const; CString operator=(const CString& q); }; First of all I'm not so sure I declared everything right. I tried googleing about it but all the tutorials about overloading explain the basic ideea which is very simple but lack to explain how and when each thing is called. For instance in my = operator the program calls CString(CString& str); but I have no ideea why. I have also attached the cpp file below: CString::CString() { cstr=0; } CString::CString(char *str) { cstr=new char[strlen(str)]; strcpy(cstr,str); } CString::CString(CString& q) { if(this==&q) return; cstr = new char[strlen(q.cstr)+1]; strcpy(cstr,q.cstr); } CString::~CString() { if(cstr) delete[] cstr; } CString::operator char*() { return cstr; } CString::operator const char* () { return cstr; } CString CString::operator +(const CString &q) const { CString s; s.cstr = new char[strlen(cstr)+strlen(q.cstr)+1]; strcpy(s.cstr,cstr); strcat(s.cstr,q.cstr); return s; } CString CString::operator =(const CString &q) { if(this!=&q) { if(cstr) delete[] cstr; cstr = new char[strlen(q.cstr)+1]; strcpy(cstr,q.cstr); } return *this; } For testing I used a code just as simple as this CString a = CString("Hello") + CString(" World"); printf(a); I tried debugging it but at a point I get lost. First it calls the constructor 2 times for "hello" and for " world". Then it get's in the + operator which is fine. Then it calls the constructor for the empty string. After that it get's into "CString(CString& str)" and now I'm lost. Why is this happening? After this I noticed my string containing "Hello World" is in the destructor (a few times in a row). Again I'm very puzzeled. After converting again from char* to Cstring and back and forth it stops. It never get's into the = operator but neither does it go further. printf(a) is never reached. I use VisualStudio 2010 for this but it's basically just standard c++ code and thus I don't think it should make that much of a difference

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  • Difference of function argument as (const int &) and (int & a) in C++

    - by Narek
    I know that if you write void function_name(int& a), then function will not do local copy of your variable passed as argument. Also have met in literature that you should write void function_name(const int & a) in order to say compiler, that I dont want the variable passed as argument to be copied. So my question: what is the difference with this two cases (except that "const" enshures that the variable passes will not be changed by function!!!)???

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  • Problem with "moveable-only types" in VC++ 2010

    - by Luc Touraille
    I recently installed Visual Studio 2010 Professional RC to try it out and test the few C++0x features that are implemented in VC++ 2010. I instantiated a std::vector of std::unique_ptr, without any problems. However, when I try to populate it by passing temporaries to push_back, the compiler complains that the copy constructor of unique_ptr is private. I tried inserting an lvalue by moving it, and it works just fine. #include <utility> #include <vector> int main() { typedef std::unique_ptr<int> int_ptr; int_ptr pi(new int(1)); std::vector<int_ptr> vec; vec.push_back(std::move(pi)); // OK vec.push_back(int_ptr(new int(2)); // compiler error } As it turns out, the problem is neither unique_ptr nor vector::push_back but the way VC++ resolves overloads when dealing with rvalues, as demonstrated by the following code: struct MoveOnly { MoveOnly() {} MoveOnly(MoveOnly && other) {} private: MoveOnly(const MoveOnly & other); }; void acceptRValue(MoveOnly && mo) {} int main() { acceptRValue(MoveOnly()); // Compiler error } The compiler complains that the copy constructor is not accessible. If I make it public, the program compiles (even though the copy constructor is not defined). Did I misunderstand something about rvalue references, or is it a (possibly known) bug in VC++ 2010 implementation of this feature?

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  • C# XNA: What can cause SpriteBatch.End() to throw a NRE?

    - by Rosarch
    I don't understand what I'm doing wrong here: public void Draw(GameTime gameTime) // in ScreenManager { SpriteBatch.Begin(SpriteBlendMode.AlphaBlend); for (int i = 0; i < Screens.Count; i++) { if (Screens[i].State == Screen.ScreenState.HIDDEN) continue; Screens[i].Draw(gameTime); } SpriteBatch.End(); // null ref exception } SpriteBatch itself is not null. Some more context: public class MasterEngine : Microsoft.Xna.Framework.Game { public MasterEngine() { graphicsDeviceManager = new GraphicsDeviceManager(this); Components.Add(new GamerServicesComponent(this)); // ... spriteBatch = new SpriteBatch(graphicsDeviceManager.GraphicsDevice); screenManager = new ScreenManager(assets, gameEngine, graphicsDeviceManager.GraphicsDevice, spriteBatch); } //... protected override void Draw(GameTime gameTime) { screenManager.Draw(gameTime); // calls the problematic method base.Draw(gameTime); } } Am I failing to initialize something properly? UPDATE: As an experiment, I tried this to the constructor of MasterEngine: spriteBatch = new SpriteBatch(graphicsDeviceManager.GraphicsDevice); spriteBatch.Begin(); spriteBatch.DrawString(assets.GetAsset<SpriteFont>("calibri"), "ftw", new Vector2(), Color.White); spriteBatch.End(); This does not cause a NRE. hmm.... UPDATE 2: This does cause an NRE: protected override void Draw(GameTime gameTime) { spriteBatch.Begin(); spriteBatch.End(); // boned here //screenManager.Draw(gameTime); base.Draw(gameTime); }

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  • Argument type deduction, references and rvalues

    - by uj2
    Consider the situation where a function template needs to forward an argument while keeping it's lvalue-ness in case it's a non-const lvalue, but is itself agnostic to what the argument actually is, as in: template <typename T> void target(T&) { cout << "non-const lvalue"; } template <typename T> void target(const T&) { cout << "const lvalue or rvalue"; } template <typename T> void forward(T& x) { target(x); } When x is an rvalue, instead of T being deduced to a constant type, it gives an error: int x = 0; const int y = 0; forward(x); // T = int forward(y); // T = const int forward(0); // Hopefully, T = const int, but actually an error forward<const int>(0); // Works, T = const int It seems that for forward to handle rvalues (without calling for explicit template arguments) there needs to be an forward(const T&) overload, even though it's body would be an exact duplicate. Is there any way to avoid this duplication?

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  • Java static method parameters

    - by Blitzkr1eg
    Why does the following code return 100 100 1 1 1 and not 100 1 1 1 1 ? public class Hotel { private int roomNr; public Hotel(int roomNr) { this.roomNr = roomNr; } public int getRoomNr() { return this.roomNr; } static Hotel doStuff(Hotel hotel) { hotel = new Hotel(1); return hotel; } public static void main(String args[]) { Hotel h1 = new Hotel(100); System.out.print(h1.getRoomNr() + " "); Hotel h2 = doStuff(h1); System.out.print(h1.getRoomNr() + " "); System.out.print(h2.getRoomNr() + " "); h1 = doStuff(h2); System.out.print(h1.getRoomNr() + " "); System.out.print(h2.getRoomNr() + " "); } } Why does it appear to pass Hotel by-value to doStuff() ?

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  • Does a HashSet make an internal copy of added Objects?

    - by praks5432
    Let's say I have a function that is recursive and is like this public void someRecur(List<Integer>someList){ if(someBreakCondition) Set.add(someList); for(int i = 0; i < someLen ; i++){ someList.add(someInt); someRecur(someList); someList.remove(someInt); } } Does the remove affect the list that has been put into the set? What should I do to give the set an actual copy of the list?

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  • SimpleXMLElement empty object

    - by Mike
    Hi, I am trying to parse an xml file using XmlReader but although I am getting a return from the xml file for the (commission) node for some reason I am getting an empty SimpleXMLElement Object returned as well. I don't know if its something to do with while loop,switch or something I missed in the parse setup. This is the xml file I am trying to read from, as you can see there is only 1 result returned: <?xml version="1.0" encoding="UTF-8"?> <cj-api> <commissions total-matched="1"> <commission> <action-status> new </action-status> <action-type> lead </action-type> <aid> 10730981 </aid> <commission-id> 1021015513 </commission-id> <country> </country> <event-date> 2010-05-08T08:08:55-0700 </event-date> <locking-date> 2010-06-10 </locking-date> <order-id> 345007 </order-id> <original> true </original> <original-action-id> 787692438 </original-action-id> <posting-date> 2010-05-08T10:01:22-0700 </posting-date> <website-id> 3201921 </website-id> <cid> 2815954 </cid> <advertiser-name> SPS EurosportBET </advertiser-name> <commission-amount> 0 </commission-amount> <order-discount> 0 </order-discount> <sid> 0 </sid> <sale-amount> 0 </sale-amount> </commission> </commissions> </cj-api> This is my parser: <?php // read $response (xml feed) $file = "datafeed.xml"; $xml = new XMLReader; $xml->open($file); // loop to read in data while ($xml->read()) { switch ($xml->name) { // find the parent node for each commission payment case 'commission': // initalise xml parser $dom = new DomDocument(); $dom_node = $xml ->expand(); $element = $dom->appendChild($dom_node); $dom_string = $dom->saveXML($element); $commission = new SimpleXMLElement($dom_string); // read in data $action_status = $commission->{'action-status'}; $action_type = $commission->{'action-type'}; $aid = $commission->{'aid'}; $commission_id = $commission->{'commission-id'}; $country = $commission->{'country'}; $event_date = $commission->{'event-date'}; $locking_date = $commission->{'locking-date'}; $order_id = $commission->{'order-id'}; $original = $commission->{'original'}; $original_action_id = $commission->{'original_action-id'}; $posting_date = $commission->{'posting-date'}; $website_id = $commission->{'website-id'}; $cid = $commission->{'cid'}; $advertiser_name = $commission->{'advertiser-name'}; $commission_amount = $commission->{'commission-amount'}; $order_discount = $commission->{'order-discount'}; $sid = $commission->{'sid'}; $sale_amount = $commission->{'sale-amount'}; print_r($aid); break; } } ?> The result is : SimpleXMLElement Object ( [0] => 10730981 ) SimpleXMLElement Object ( ) Why is it returning the second object: SimpleXMLElement Object ( ) and what do I need to do correct it? Thanks.

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  • Pointing class property to another class with vectors

    - by jmclem
    I've got a simple class, and another class that has a property that points to the first class: #include <iostream> #include <vector> using namespace std; class first{ public: int var1; }; class second{ public: first* classvar; }; Then, i've got a void that's supposed to point "classvar" to the intended iteration of the class "first". void fill(vector<second>& sec, vector<first>& fir){ sec[0].classvar = &fir[0]; } Finally the main(). Create and fill a vector of class "first", create "second" vector, and run the fill function. int main(){ vector<first> a(1); a[0].var1 = 1000; vector<second> b(1); fill(b, a); cout << b[0].classvar.var1 << '\n'; system("PAUSE"); return 0; } This gives me the following error: 1>c:\...\main.cpp(29) : error C2228: left of '.var1' must have class/struct/union 1> type is 'first *' And I can't figure out why it reads the "classvar" as the whole vector instead of just the single instance. Should I do this cout << b[0].classvar[0].var1 << '\n'; it reads perfectly. Can anyone figure out the problem? Thanks in advance

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  • Is there any way to pass an anonymous array as an argument in C++?

    - by Jeremy Friesner
    Hi all, I'd like to be able to declare an array as a function argument in C++, as shown in the example code below (which doesn't compile). Is there any way to do this (other than declaring the array separately beforehand)? #include <stdio.h> static void PrintArray(int arrayLen, const int * array) { for (int i=0; i<arrayLen; i++) printf("%i -> %i\n", i, array[i]); } int main(int, char **) { PrintArray(5, {5,6,7,8,9} ); // doesn't compile return 0; }

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  • perl: added hash entry in a subroutine is lost

    - by hansi
    Why is the hash empty on the second call of printHash? my %hash = (); addToHash(\%hash); printHash(\%hash); sub addToHash { my %hash = %{$_[0]}; $hash{"test"} = "test"; printHash(\%hash); } sub printHash { print "printHash: \n"; my %hash = %{$_[0]}; foreach my $key (keys %hash) { print "key: $key, value: $hash{$key}\n"; } } Output: printHash: key: test, value: test printHash:

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  • .click() callback references local variable from the calling method instead of copying by value

    - by Eric Freese
    The following jQuery Javascript code is included on an otherwise empty page. $(function() { for (var i = 0; i < 10; i++) { element = $('<div>' + i + '</div>'); element.click(function() { alert(i); }); $('body').append(element); } }); The desired behavior is that this code should generate 10 div elements numbered from 0 to 9. When you click on a div element, an alert popup will show the number of the div element you clicked on (i.e. if a user clicks on the div element labeled '4', the alert popup should show the number 4). The alert popup instead shows the number 10 regardless of which div element is clicked on. How can I modify this code to make it behave in the desired way?

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