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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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  • C99 variable length automatic array performance

    - by aaa
    Is there significant cpu/memory overhead associated with using automatic arrays with g++/Intel on 64-bit x86 linux platform? int function(int N) { double array[N]; overhead compared to allocating array before hand (assuming function is called multiple times) overhead compared to using new overhead compared to using malloc The range of N may be from 1kb to 16kb roughly, stack overrun is not a problem.

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  • Getting a Type variable knowing the name of type C#

    - by StuffHappens
    Hello! I'm developing a TypeTranslator class which has a method Type TranslateType(Type type). This method gets a type of an interface and if there's a class of interface name without leading I it creates it, otherwise an exception is raised. Here's some code to clearify what's written before: class Program { interface IAnimal { } class Animal : IAnimal { } void Function() { TypeTranslator typeTranslator = new TypeTranslator(); Assert(typeTranslator.TranslateType(typeof(IAnimal) == typeof(Animal))); } } Is it possible to get what I want? Thank you for your help!

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  • Dynamic allocating of const member structures

    - by Willy
    I've got class which is using plain-only-data struct with const variables and I'm not sure, if I'm allocating these structures in a proper way. It looks more or less like: #include <cstdlib> #include <iostream> using std::cout; using std::endl; struct some_const_struct { const int arg1; const int arg2; }; class which_is_using_above_struct { public: some_const_struct* m_member; const some_const_struct* const m_const_member; public: const some_const_struct& get_member() const { return *m_member; } const some_const_struct& get_const_member() const { return *m_const_member; } void set_member(const int a, const int b) { if(m_member != NULL) { delete m_member; m_member = NULL; } m_member = new some_const_struct((some_const_struct){a, b}); } explicit which_is_using_above_struct(const int a, const int b) : m_const_member(new some_const_struct((const some_const_struct){a, b})) { m_member = NULL; } ~which_is_using_above_struct() { if(m_member != NULL) { delete m_member; } if(m_const_member != NULL) { delete m_const_member; } } }; int main() { which_is_using_above_struct c(1, 2); c.set_member(3, 4); cout << "m_member.arg1 = " << c.get_member().arg1 << endl; cout << "m_member.arg2 = " << c.get_member().arg2 << endl; cout << "m_const_member.arg1 = " << c.get_const_member().arg1 << endl; cout << "m_const_member.arg2 = " << c.get_const_member().arg2 << endl; return 0; } I'm just not quite sure if the statement: m_member = new some_const_struct((some_const_struct){a, b}); doesn't produce unnessesary use of some_const_struct's copy constructor, ergo allocating that struct twice. What do you think? And is it reasonable to make that struct's members const? (they're not supposed to change in their lifetime at all)

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  • C++ Dynamic Allocation Mismatch: Is this problematic?

    - by acanaday
    I have been assigned to work on some legacy C++ code in MFC. One of the things I am finding all over the place are allocations like the following: struct Point { float x,y,z; }; ... void someFunc( void ) { int numPoints = ...; Point* pArray = (Point*)new BYTE[ numPoints * sizeof(Point) ]; ... //do some stuff with points ... delete [] pArray; } I realize that this code is atrociously wrong on so many levels (C-style cast, using new like malloc, confusing, etc). I also realize that if Point had defined a constructor it would not be called and weird things would happen at delete [] if a destructor had been defined. Question: I am in the process of fixing these occurrences wherever they appear as a matter of course. However, I have never seen anything like this before and it has got me wondering. Does this code have the potential to cause memory leaks/corruption as it stands currently (no constructor/destructor, but with pointer type mismatch) or is it safe as long as the array just contains structs/primitive types?

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  • Variable is Undefined

    - by Matrym
    var bod = document.getElementsByTagName("body")[0]; bod.style.backgroundColor = setBgcolor.defaults.color; Why does bod come back as undefined when the above is called at window.onload?

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  • Send a variable on the heap to another thread

    - by user1201889
    I have a strange problem in C++. An address of a Boolean gets "destroyed" but it doesn't get touched. I know that there are beater way's to accomplish what I try to do, but I want to know what I do wrong. I have a main class; this main class contains a vector of another class. There is a strange problem when a new instance gets created of this object. This is how my code works: There will start a thread when the constructor gets called of the “2nd”object. This thread gets as Parameter a struct. This is the struct: struct KeyPressData { vector<bool> *AutoPressStatus; vector<int> *AutoPressTime; bool * Destroy; bool * Ready; }; The struct gets filled in the constructor: MultiBoxClient::MultiBoxClient() { //init data DestroyThread = new bool; ReadyThread = new bool; AutoThreadData = new KeyPressData; //Reseting data *DestroyThread = false; *ReadyThread = false; //KeyPressData configurating AutoThreadData->AutoPressStatus = &AutoPressStatus; AutoThreadData->AutoPressTime = &AutoPressTime; AutoThreadData->Destroy = DestroyThread; AutoThreadData->Ready = ReadyThread; //Start the keypress thread CreateThread(NULL,NULL,(LPTHREAD_START_ROUTINE)AutoKeyThread,AutoThreadData,NULL,NULL); } As long as the constructor is running will the program run fine. But when the constructor closes the address of the “AutoThreadData-Destroy” will get corrupted. The program will crash when I call the value of the pointer. void WINAPI AutoKeyThread(void * ThreadData) { KeyPressData * AutoThreadData = (KeyPressData*)ThreadData; while(true) { if(*AutoThreadData->Destroy == true) //CRASH { *AutoThreadData->Ready = true; return; } Sleep(100); } } What did I test: I logged the address of the AutoThreadData and the AutoThreadData-Destroy when the constrcutor is running and clossed; the AutoThreadData address is equal to AutoThreadData when the constructor is closed. So there is no problem here. The address of AutoThreadData-Destroy gets destroyed when the constructor is closed. But how can this happen? The Boolean is on the heap and the KeyPressData struct (AutoThreadData) is on the heap. Destroy before: 00A85328 Destroy after: FEEEFEEE Can someone maby explain why this crash? I know that I can send a pointer to my class to the thread. But I want to know what goes wrong here. That way I can learn from my mistakes. Could someone help me with this problem? Thanks!

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  • variable argument list in windows va_list

    - by shrikant
    hi, I wanted to have function which will accept as foo(...) { } usage of this would be foo(1,2,3); foo(1) foo(1,2,3,4,5,5,6); va_list can be used but again for that I have to pass foo(int count, ...), as this at run time i dont know how many argument i have. any pointer would be appreciated Thanks

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  • Unreachable, existing variable

    - by Oden
    I'm new at as3, maybe thats the reason why i don't understand, why the setInterval causes an error. <mx:Script> <![CDATA[ import flash.utils.setInterval; import mx.controls.Alert; [Bindable] public var MyInt:int = 500; setInterval(function():void{ ++MyInt; },1000); ]]> </mx:Script> I have a label where the value of MyInt gets visible, the bind works perfect, i've tested it several ways, and i i create a button it grows the number, but if i use the setInterval function i get an error: Access of undefined property myInt. Why? What does cause this? Please explain it, so I can avoid errors like this. Thanks

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  • HTML dynamic tags insert looks different compared to static layout

    - by Andrew Florko
    I program HTML interface with jquery. There is editable list of publications on the page and user can click any publication to edit details. Popup window appears with data and there is list of authors embedded into details form. There are edit/delete buttons against every of them + "add new author" button. User manipulates authors without page reload. When I insert a new author there are new edit/delete buttons created dynamically & embedded into page. I insert tags like this: <td class="author-actions"> <img onclick='edit(id)' .../> <img onclick='delete(id)' .../> </td> Just the same html-layout that is sent from web-server when popup window appears. But somehow it looks different. There is extraspace between images though firebug demonstrates the same css attributes applied. If I select with mouse inserted layout with IE, somehow it can reorder and become the same-looklike as the those, send by web-server. What can it be?

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  • C++ Dynamic object construction

    - by Rajesh Subramanian
    I have a base class, class Msg { ParseMsg() { ParseMsgData(); ParseTrailer(); } virtual void ParseMsgData() = 0; ParseTrailer(); }; and derived classes, class InitiateMsg { void ParseMsgData() { ... } }; class ReadOperationMsg { void ParseMsgData() { ... } }; class WriteOperationMsg { void ParseMsgData() { ... } }; and the scenario is below, void UsageFunction(string data) { Msg* msg = ParseHeader(data); ParseMsg } Msg* ParseHeader(string data) { Msg *msg = NULL; .... switch() { case 1: msg = new InitiateMsg(); break; case 2: msg = new ReadOperationMsg{(); break; case 3: msg = new WriteOperationMsg{(); break; .... } return msg; } based on the data ParseHeader method will decide which object has to be created, So I have implemented ParseHeader function outside the class where I am using. How can I make the ParseHeader function inside the Msg class and then use it? In C# the same is achieved by defining ParseHeader method as static with in class and use it from outside,

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  • Asp.Net MVC3 - How create Dynamic DropDownList

    - by Bibo
    I found many articles on this but still I don´t know how exactly to do this. I am trying to create my own blog engine, I have View for create article (I am using EF and Code first) and now I must fill number of category in which article should be add but I want to change it to dropdownlist with names of categories. My model looks this: public class Article { public int ArticleID { get; set; } [Required] public string Title { get; set; } [Required] public int CategoryID { get; set; } public DateTime Date { get; set; } [Required()] [DataType(DataType.MultilineText)] [AllowHtml] public string Text { get; set; } public virtual Category Category { get; set; } public IEnumerable<SelectListItem> Categories { get; set; } public virtual ICollection<Comment> Comments { get; set; } } public class Category { public int CategoryID { get; set; } [Required] public string Name { get; set; } public virtual ICollection<Article> Articles { get; set; } } I know I must use Enum (or I think) but I am not exactly sure how. I don´t know which tutorial from that I found is best for me.

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  • Dynamic swappable Data Access Layer

    - by Andy
    I'm writing a data driven WPF client. The client will typically pull data from a WCF service, which queries a SQL db, but I'd like the option to pull the data directly from SQL or other arbitrary data sources. I've come up with this design and would like to hear your opinion on whether it is the best design. First, we have some data object we'd like to extract from SQL. // The Data Object with a single property public class Customer { private string m_Name = string.Empty; public string Name { get { return m_Name; } set { m_Name = value;} } } Then I plan on using an interface which all data access layers should implement. Suppose one could also use an abstract class. Thoughts? // The interface with a single method interface ICustomerFacade { List<Customer> GetAll(); } One can create a SQL implementation. // Sql Implementation public class SqlCustomrFacade : ICustomerFacade { public List<Customer> GetAll() { // Query SQL db and return something useful // ... return new List<Customer>(); } } We can also create a WCF implementation. The problem with WCF is is that it doesn't use the same data object. It creates its own local version, so we would have to copy the details over somehow. I suppose one could use reflection to copy the values of similar fields across. Thoughts? // Wcf Implementation public class WcfCustomrFacade : ICustomerFacade { public List<Customer> GetAll() { // Get date from the Wcf Service (not defined here) List<WcfService.Customer> wcfCustomers = wcfService.GetAllCustomers(); // The list we're going to return List<Customer> customers = new List<Customer>(); // This is horrible foreach(WcfService.Customer wcfCustomer in wcfCustomers) { Customer customer = new Customer(); customer.Name = wcfCustomer.Name; customers.Add(customer); } return customers; } } I also plan on using a factory to decide which facade to use. // Factory pattern public class FacadeFactory() { public static ICustomerFacade CreateCustomerFacade() { // Determine the facade to use if (ConfigurationManager.AppSettings["DAL"] == "Sql") return new SqlCustomrFacade(); else return new WcfCustomrFacade(); } } This is how the DAL would typically be used. // Test application public class MyApp { public static void Main() { ICustomerFacade cf = FacadeFactory.CreateCustomerFacade(); cf.GetAll(); } } I appreciate your thoughts and time.

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  • PHP concatenate variable

    - by Jerry
    Hi guys. Might be an easy question for you guys. can't find it on google. I am trying to concatenate two variables name; $i=0; for ($i=0;$i<5;$i++){ if($array[$i]>0){ $test.$i=//do something }else{ $test.$i=//do something } } //echo $test0 gives me nothing. //echo $test1 gives me nothing. I know I can't use $test.$i but don't know how to do this.Any helps? Thanks!

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  • dynamic inheritance without touching classes

    - by Jasper
    I feel like the answer to this question is really simple, but I really am having trouble finding it. So here goes: Suppose you have the following classes: class Base; class Child : public Base; class Displayer { public: Displayer(Base* element); Displayer(Child* element); } Additionally, I have a Base* object which might point to either an instance of the class Base or an instance of the class Child. Now I want to create a Displayer based on the element pointed to by object, however, I want to pick the right version of the constructor. As I currently have it, this would accomplish just that (I am being a bit fuzzy with my C++ here, but I think this the clearest way) object->createDisplayer(); virtual void Base::createDisplayer() { new Displayer(this); } virtual void Child::createDisplayer() { new Displayer(this); } This works, however, there is a problem with this: Base and Child are part of the application system, while Displayer is part of the GUI system. I want to build the GUI system independently of the Application system, so that it is easy to replace the GUI. This means that Base and Child should not know about Displayer. However, I do not know how I can achieve this without letting the Application classes know about the GUI. Am I missing something very obvious or am I trying something that is not possible?

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  • Why wont extern link to a static variable?

    - by Jared P
    Why does extern int n not compile when n is declared (in a different file) static int n, but works when declared int n? (Both of these declarations were at file scope.) Basically, why is int n in file scope not the same as static int n in the same scope? Is it only in relation to extern? If so, what about extern am I missing?

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  • jQuery Running a function in a context and adding to a variable

    - by Mark
    For this question I'm going to give a simplified example of what I want to do, and the function I want to learn to write. var collection = ''; <div id='container'> <span>1</span> <span>2</span> <span>3</span> </div> What I want to do this, for every span in the div, take its text, add it to the collection. So ideally it would look like: $('#container').addtoCollection(collection); The method would be something like: $(this).find('span').each(function () { collection = collection + $(this).text(); }). Where the first this would equal #container. So in the end you can do: console.log(collection); and get: 123 How do I write the function that does this? Thanks!

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  • method returning wrong variable

    - by cocoanewbie
    This class I'm working with has three instance variables I'm interested in, NSmutablearrays xArray yArray and zArray, there are also other NSmutablearrays, a, bArray and c. I just added accessors - (NSMutableArray *) xArray { return xArray; } ditto for y and z. However, it's returning yArray, zArray and bArray for some reason. Why is that happening? Okay, I just changed the names of the methods to GetXArray and everything seems to be returning the right variables. Now I'm really confused. How the heck did this happen and how do I prevent this from happening in the future?

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  • Pass variable by Post method from JQuery UI Autocomplete to PHP page

    - by Shahriar N Khondokar
    I have two JQuery UI autocomplete input fields. When an option is selected in the first one, the value of the selection will be used as condition for a database query that will send the source data for the second autocomplete field. My problem is how do I send the value of the first selection to the PHP page via Post method? The code so far is shown below (this code is from a tutorial which used the GET method; but I want to use Post): <script> $("input#divisions").autocomplete ({ //this is the first input source : [ { value: "81", label: "City1" }, { value: "82", label: "City2" }, { value: "83", label: "City3" } ], minLength : 0, select: function(event, ui) { $('#divisions').val(ui.item.label); return false; }, focus: function(event, ui){ $('#divisions').val(ui.item.label); return false; }, change: function(event, ui){ //the tutorial has this value sent by variables in the URL; I want the selection value sent by POST. How can I change this? c_t_v_choices = "c_t_v_choices.php?filter=" + ui.item.value; $("#c_t_v").autocomplete("option", "source", c_t_v_choices); } }).focus (function (event) { $(this).autocomplete ("search", ""); }); $("#c_t_v").autocomplete({ source: "", minLength: 2, select: function(event,ui){ //$('#city').val(ui.item.city); } }); </script> Can anyone please help? Dont hesitate to let me know if you have any questions.

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  • Flash Media Server dynamic file naming

    - by flying_tiger
    I'm trying to figure out most efficient/safe way to name recorded streams on FMS. The case is to get listing of recorded streams from the server (eg. rec_001, rec_002...) and dynamically add rec_003 filename to the new stream that is being recorded. I'm thinking about either using FMS File Object and put everything in array of files every time I start recording procedure or to create XML file that would serve as a database of file names. I'm searching for a solution efficient for MULTIPLE connections at a time and large amount of files. Which one of presented would be the best for this purpose? Or do you have any better suggestions of solving this problem?

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  • should variable be released or not? iphone-sdk

    - by psebos
    Hi, I have the following piece of code from a book. There is this function loadPrefs where the NSString *userTimeZone is being released before the end of the function. Why? The string was not created with alloc and I assume that the stringForKey function returns an autoreleased NSString. Is this an error or am I missing something? Is it an error in the book? (I new into objective-C) In the documentation for stringForKey the only thing it mentions is: Special Considerations The returned string is immutable, even if the value you originally set was a mutable string. The code: - (void) loadPrefs { timeZoneName = DefaultTimeZonePref; NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults]; NSString *userTimeZone = [defaults stringForKey: TimeZonePrefKey]; if (userTimeZone != NULL) timeZoneName = userTimeZone; [userTimeZone release]; show24Hour = [defaults boolForKey:TwentyFourHourPrefKey]; } Thanks!!!!

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