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  • Should I learn Haskell or F# if I already know OCaml?

    - by Unknown
    I am wondering if I should continue to learn OCaml or switch to F# or Haskell. Here are the criteria I am most interested in: Longevity Which language will last longer? I don't want to learn something that might be abandoned in a couple years by users and developers. Will Inria, Microsoft, University of Glasgow continue to support their respective compilers for the long run? Practicality Articles like this make me afraid to use Haskell. A hash table is the best structure for fast retrieval. Haskell proponents in there suggest using Data.Map which is a binary tree. I don't like being tied to a bulky .NET framework unless the benefits are large. I want to be able to develop more than just parsers and math programs. Well Designed I like my languages to be consistent. Please support your opinion with logical arguments and citations from articles. Thank you.

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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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  • Why is C++ fwrite() producing larger output in release?

    - by waffleShirt
    I recently wrote an implementation of the Canonical Huffman compression algorithm. I have a 500kb test file that can be compressed to about 250kb when running the debug and release builds from within Visual Studio 2008. However when I run the release build straight from the executeable the test file only compresses to about 330kb. I am assuming that something is going wrong when the file is written using fwrite(). I have tested the program and confirmed that uncompressing the files always produces the correct uncompressed file. Does anyone know why this could possibly be? How could the same executeable file be producing different sized outputs based on where it is launched from?

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  • Windows API Textfield with offset characters

    - by genesys
    Hi there! Is it possible using the Windows API, to create a textfield that lets me offset characters by exact pixels? if so - how? for example, I would like to place two O letters on top of each other, such that they form something like an 8 ? context is an application for a language where most of the glyphs are written left to right, but sometimes some of the glyphs are stacket on top of each other. Windows API because the framework we're using already uses the Windows API for the whole GUI. Thanks!

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  • Qt and finding partial matches in a QList

    - by ExpatEgghead
    I have a struct viz: struct NameKey { std::string fullName; std::string probeName; std::string format; std::string source; } which are held in a QList: QList<NameKey> keyList; what I need to do is find an occurence in keyList of a partial match where the search is for a NameKey that only has two members filled. All the keyList entries are full NameKey's. My current implementation is , well, boring in the extreme with too many if's and conditions. So, If I have a DataKey with a fullName and a format I need to find all the occurences in keyList which match. Any useful Qt/boost things available?

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  • Why exactly is calling the destructor for the second time undefined behavior in C++?

    - by sharptooth
    As mentioned in this answer simply calling the destructor for the second time is already undefined behavior 12.4/14(3.8). For example: class Class { public: ~Class() {} }; // somewhere in code: { Class* object = new Class(); object->~Class(); delete object; // UB because at this point the destructor call is attempted again } In this example the class is designed in such a way that the destructor could be called multiple times - no things like double-deletion can happen. The memory is still allocated at the point where delete is called - the first destructor call doesn't call the ::operator delete() to release memory. For example, in Visual C++ 9 the above code looks working. Even C++ definition of UB doesn't directly prohibit things qualified as UB from working. So for the code above to break some implementation and/or platform specifics are required. Why exactly would the above code break and under what conditions?

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  • Added a tableview in a viewcontroller. How do I load tableview cells

    - by user1509593
    I have a view controller In storyboard, added tableview to view controller. Created an IBOutlet for tableview to View controller's header file. The view controller's header file includes an resultsarray Changed the @interface to include delegates <\UITableViewDelegate, UITableViewDataSource View controller implementation file has mandatory tableview protocols (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath The view controller has search button in storyboard and IBAction in view controller header file. On click of search button, results are obtained. How do I load the array and redisplay tableview with results in search method. After I loaded the results in array, I tried [self viewdidload];, hoping the cells will be loaded. But didn't. I thought of calling [self.detailView cellForRowAtIndexPath:?indexpath], but dontknow what the value of index path is. Appreciate help from guru's to load the UItableviewcell Thanks

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  • Looking for suggestions about an architecture of a MultiThreaded app.

    - by Dimitri
    Hello everyone. I am looking to develop a multithreaded application that will be running in unconditional loop and processing high volume of data. High volume is 2000+ records per minute. Processing will involve data retrieval, calculations and data updates. I need the application to perform so that there is virtually no back log, meaning i need to be able to finish up all of the 2000 points in one minute or even faster. Our current implementation features a multithreaded application that is spawn multiple times (from 10 to 20) and we are noticing that it's not handling data as expected and i even feel that instances of the application compete with each other for processor time and eventually if not slowing, not benefiting each other for sure. I would like to know what would be the best approach: have a single instance running but maximize threads that can run simultaneously? or is there other ways i don't know? I'm open to suggestions. Thank you in advance

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  • Does Ruby/Rails require more unit testing than say a PHP app?

    - by Blankman
    I don't find the unit testing push in the PHP market like I see/read in the ruby/rails arena. Could one just as easily NOT unit test in ruby/rails as in php, or is ruby just too bendable and breakable that it "more" recommended to test in ruby than in php? Meaning there are large code bases like vBulletin, and from what I can tell, they don't unit test. I hope you understand what I am asking here, not the pros/cons of testing, or whether one should test or not, but rather, does one language need to be tested more than another? maybe its easy to write buggy code, or break during refactoring etc.

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  • dynamic memory allocation of 2d array in which columns are of different size

    - by vishal kumar
    i want to create a 2d array dynamically in c++ language. But in that 2d array columns should be of different size. i mean to say that 2d array should not be in M * N. It should be something like.... 1 2 next line 3 4 5 next line 2 3 4 5 next line 5 next line 4 5 7 I am able to create 2d array in above manner but how to display content of array continously create a problem for me. Please anyone explain me how to come up with this problem.

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  • Recommend a local LDAP store for development

    - by Paul Stovell
    Our project uses an LDAP repository for storing users. In production this will be Active Directory. For development, we seem to have a couple of options: Install an AD LDS instance that everyone uses Install an AD LDS instance on every developer machine We're trying to keep the 'F5' experience as lightweight as possible, so installing things or relying on a central AD store aren't my favorite ideas. There are other LDAP servers, like Open LDAP. I was hoping there might be an LDAP server that simply talks to an XML file. This would allow us to store the XML file in source control and have something that is fast and works. Our nightly builds would still use AD to pick up any differences, but the hope is since we're using LDAP it should Just Work. Can you recommend an LDAP implementation that works well for zero-config shared-nothing development?

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  • Should a protected property in a C# child class hide access to a public property on the parent?

    - by Tim
    I have the following code: public class Parent { public string MyField { get; set; } } public class Child : Parent { protected new int MyField { get; set; } } I try and access this with: static void Main(string[] args) { Child child = new Child(); child.MyField = "something"; } Visual studio 2008 compiles this without comment, but under Mono (2.4.2, Ubuntu) I get the error message 'HideTest.Child.MyField' is inaccessible due to its protection level (CS0122) Is one implementation or the other more compliant with the standard here?

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  • Alternatives to C++ Reference/Pointer Syntax

    - by Jon Purdy
    What languages other than C and C++ have explicit reference and pointer type qualifiers? People seem to be easily confused by the right-to-left reading order of types, where char*& is "a reference to a pointer to a character", or a "character-pointer reference"; do any languages with explicit references make use of a left-to-right reading order, such as &*char/ref ptr char? I'm working on a little language project, and legibility is one of my key concerns. It seems to me that this is one of those questions to which it's easy for a person but hard for a search engine to provide an answer. Thanks in advance!

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  • Grouped UITableView's cell separator missing when setting backgroundView with an image

    - by Howard Spear
    I have a grouped UITableView with a custom UITableViewCell class and I am adding a custom background image to each cell. However, when I do this, the cell's separator is not visible. If simply switch the table style to Plain instead of Grouped, the separator is showing up. I need the grouped table - how do I make the separator show up? Here's my code: @interface MyCustomTableViewCell : UITableViewCell @end @implementation MyCustomTableViewCell // because I'm loading the cell from a xib file - (id)initWithCoder:(NSCoder *)coder { self = [super initWithCoder:coder]; if (self) { // Create a background image view. self.backgroundView = [[UIImageView alloc] init]; } return self; } // MyViewController - (UITableViewCell *)tableView:(UITableView *)aTableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { // // standard cell dequeue + create cell code here // // // Configure the cell background now // UIImage *backgroundImage = [UIImage imageNamed:@"odd_row.png"]; if (indexPath.row % 2 == 0) { backgroundImage = [UIImage imageNamed:@"even_row.png"]; } UIImageView *backgroundView = (UIImageView *)cell.backgroundView; backgroundView.image = backgroundImage; }

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  • listbox isSelected databinding in DataTemplate

    - by Kinmarui
    I try to simply databind IsSelected property with IsSelected field in my class. But after I change the value in code its doesn't change the property, neither does clicking on ListBoxItem change the field value. XAML: <FlipView ItemsSource="{Binding Source={StaticResource itemsViewSource}}" ... > <FlipView.ItemTemplate> <DataTemplate> <UserControl Loaded="StartLayoutUpdates" Unloaded="StopLayoutUpdates"> <!-- other controls --> <ListBox Grid.Row="1" Grid.ColumnSpan="3" SelectionMode="Multiple" VerticalAlignment="Center" ItemsSource="{Binding Answers}"> <ListBox.Resources> <local:LogicToText x:Key="logToText" /> </ListBox.Resources> <!-- bind IsSelected only in one way from code to content --> <ItemsControl.ItemTemplate> <DataTemplate> <ListBoxItem IsSelected="{Binding IsSelected, Mode=TwoWay, Converter={StaticResource logToText}}" Content="{Binding IsSelected, Mode=TwoWay, Converter={StaticResource logToText}}"> </ListBoxItem> </DataTemplate> </ItemsControl.ItemTemplate> <!-- not working at all <ListBox.Resources> <Style TargetType="ListBoxItem"> <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}"/> <Setter Property="Content" Value="{Binding IsSelected, Mode=TwoWay}"/> </Style> </ListBox.Resources>--> </ListBox> </UserControl> </DataTemplate> </FlipView.ItemTemplate> </FlipView> Code: Answers private ObservableCollection<PrawoJazdyDataAnswer> _answers = new ObservableCollection<PrawoJazdyDataAnswer>(); public ObservableCollection<PrawoJazdyDataAnswer> Answers { get { return this._answers; } } Single item(Answer) public class PrawoJazdyDataAnswer : NPCHelper// PrawoJazdy.Common.BindableBase { public PrawoJazdyDataAnswer(String ans, bool ansb) { this._ans = ans; this._isSelected = ansb; } public override string ToString() { return _isSelected.ToString(); } //Only For debug purposes normally return _ans; private string _ans; public string Ans { get { return this._ans; } //set { this.SetProperty(ref this._ans, value); } } private bool _isSelected; public bool IsSelected { get { return this._isSelected; } set { _isSelected = value; FirePropertyChanged("IsSelected"); //this.SetProperty(ref this._isSelected, value); } } } FirePropertyChanged public class NPCHelper : INotifyPropertyChanged { public event PropertyChangedEventHandler PropertyChanged; public void FirePropertyChanged(string prop) { if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(prop)); } } Converter(which sometimes seems to be needed and others not..., I tried ~10 approaches from different tutorials/examples) public class LogicToText : IValueConverter { /// <summary> /// /// </summary> public object Convert(object value, Type targetType, object parameter, string language) { //if (value == null || (bool)value == false) // return "False"; return value.ToString(); } /// <summary> /// /// </summary> public object ConvertBack(object value, Type targetType, object parameter, string language) { return value.ToString().Contains("True") ? true : false; } Thanks in advance, and sorry for my English(still learning). @edit Thanks for quick reply. For test purposes i created a button and text block: It's in other controls part (above list box, but in FlipView) <Button Click="spr" >Sprawdz</Button> <TextBlock Text="{Binding Answers[0].IsSelected, Mode=TwoWay}" > </TextBlock> Click method private void spr(object sender, RoutedEventArgs e) { var ans = ((PrawoJazdyDataQuestion)this.flipView.SelectedItem).Answers; foreach (var item in ans) item.IsSelected = item.IsSelected ? false : true; } As I wrote when i'm changing data from code side its change text, but not appearance of ListBoxItem, and if i just select it on ListBox its doesn't change the date i textblock neither in ListBox itself.

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  • Execute a method less times possible - PHP

    - by serhio
    I have a site in multiple languages. I have a method that returns me the today currencies in a array. I display that currencies in a table then. // --- en/index.php <?php include_once "../exchangeRates.php"; $currencies = ReadExchangeRates(); // --- fr/index.php <?php include_once "../exchangeRates.php"; $currencies = ReadExchangeRates(); ... // somewhere in the page <td><?php echo $currencies["eur"]["today"]; ?></td> So, every time I load, en/ or fr/ or other language, I request the exchange rates from a external site. Can I optimize this behavior (reading once per day or session)? maybe to store a global variable and check the update date?

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  • android dev: how to implement for add method in menu interface?

    - by wsgjj
    who knows about the method "add" in menu interface? how to implement exactly? which is it's imlementation class? i couldn't find detail implementation in source code of sdk. i want to check how to implement in android source code for "add" method. e.g. public boolean onCreateOptionsMenu(Menu menu) { menu.***add***(0, MENU_NEW_GAME, 0, "New Game"); menu.add(0, MENU_QUIT, 0, "Quit"); return true; } thanks in advance!

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  • any ways saving user information without db

    - by hguser
    Hi: I have a application which require login,but the number of user who use the application is no more than 40. And In the application,I get some data from the sql server database where I juse have read permission,also I can not create a table in the db for user validate. ALso I do not think it is a good idea to create a user table in other database on another machine.(for example,I can create a user table in the mysql another machine,but is it desireable just for user validating)? Now I just save the user info in a .properties file,any other good idea? BTW,the programe language used in my application is java.

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  • Working with Form Array's in Coldfusion?

    - by Jakub
    I have no idea how to handle this in coldfusion 9, I have a form being submitted (POST) with element checkboxes, called items[]. When I do a <cfdump var="#form#" /> no-problem, I get all the items shown with the proper names like items[] eg: struct ITEMS[] 13,14 FIELDNAMES ITEMS[] however doing a <cfdump var="#form.items[]#" /> results in an error. How do I access the CF9 field values? Somehow loop through it? I cannot seem to do anything with the array to get the id's out of it? Thoughts, I'm kindof stumped and coldfusion isn't the easiest language to find examples / references on the net ;) Is there a correct way to deal with this? I need to get the ID's out of there so I can referenc what lines were checked in the form, so I can follow up with an action. Thanks!

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  • Making uppercase of std::string

    - by Daniel K.
    Which implementation do you think is better? std::string ToUpper( const std::string& source ) { std::string result; result.reserve( source.length() ); std::transform( source.begin(), source.end(), result.begin(), std::ptr_fun<int, int>( std::toupper ) ); return result; } and... std::string ToUpper( const std::string& source ) { std::string result( source.length(), '\0' ); std::transform( source.begin(), source.end(), result.begin(), std::ptr_fun<int, int>( std::toupper ) ); return result; } Difference is that the first one uses reserve method after the default constructor, but the second one uses the constructor accepting the number of characters.

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  • Declaring and creating an object then adding to collection VS Adding object to collection using new

    - by ZeeMan
    Ok so the title may have been confusing so i have posted 2 code snippets to illustrate what i mean. NOTE: allUsers is just a collection. RegularUser regUser = new RegularUser(userName, password, name, emailAddress); allUsers.Add(regUser); VS allUsers.Add(new RegularUser(userName, password, name, emailAddress)); Which snippet A or B is better and why? What are the advantages or disadvantages? The example i wrote was C# but does the language (C#, Java etc) make a difference?

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  • How to save state of the app when app terminates?

    - by user164589
    Hi guys. I am trying to save the app state by encoding when the app terminates. I've found the solution related this issue. But I don't know how to use. I am really trying to make encoding and decoding like this: http://cocoaheads.byu.edu/wiki/nscoding in CustomObject.h @interface CustomObject : NSObject <NSCoding> { NSArray *someArray; } in CustomObject.m @implementation CustomObject // Other method implementations here - (void) encodeWithCoder:(NSCoder*)encoder { [encoder encodeObject:someArray forKey:@"someArray"]; } - (id) initWithCoder:(NSCoder*)decoder { if (self = [super init]) { someArray = [[decoder decodeObjectForKey:@"someArray"] retain]; } return self; } @end My object to save is another NSArray. Not "someArray" in CustomObject. We call it that "MySaveObject". I want to pass "MySaveObject" to "someArray" in CustomObject. Actually I don't know how to encode "MySaveObject" and to pass to "someArray" in CustomObject. Thanks in advance.

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  • How can we manage ProductVersion(A Windows Resource) automatically?

    - by Benjamin
    Windows resources have a FileVersion and a ProductVersion. In native development environment(eg. Win32 app, device driver) How do you manage the ProductVerion automatically? My language is c/c++. And I use Visual Studio 2008. I want to increase the version automatically when I build my projects. Is it possible? I guess there is a simple(and good) way. Thanks in advance.

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  • Can a program have a few IFs and only one Else structures?

    - by kwokwai
    Hi all, When I was doing some JQuery and PHP, I noticed the If-else patterns were treated differently and varied from one language to another. Say I got a simple input text field in a HTML and I was using some Ifs and Elses to check the value input into the text field. Text: <input type="text" name="testing"/> In JQuery, I got some codes as follows: if($("#testing").val()==1){ //do something } if($("#testing").val()=="add"){ //do something } else{ //do something } if($("#testing").val()=="hello"){ //do something } How come JQuery and PHP treated the Else statement differently? I mean in JQuery, the third If statement was still proceeded even if it had gone to the Else statement, but it stopped after the Else statement when I repeated the code in PHP script.

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  • ASP.NET web site running in IIS and hosting WCF service fails to get connections on the TCP server

    - by Salil
    I am using the combination of Silverlight client application along with ASP.NET web site running in IIS and hosting WCF service. This WCF service uses the library that starts a TCP server and and initiates requests to the connected TCP clients when the silverlight client application makes the WCF async requests. When I use this library in a local WPF application, the TCP server is able to receive client connection requests and I can get info from these clients. But when I use the same library from the implementation of the WCF service inside the ASP .NET web site project (+ Silverlight client), the server strangely does not receive any connection requests i.e. when I create TcpListener object and issue a start, nothing happens (nor an exception is generated). My setup is I am using the Ethernet for the Internet and Wi-Fi for the TCP clients. Is the WCF service getting confused because of this? Is there any special WCF settings I should put in for TcpListener.Start to work?

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