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  • Create Generic Class Instance from Static Method in a Derived Class

    - by user343547
    I have a class in C# with a template and static method similar to class BClass<T> { public static BClass<T> Create() { return new BClass<T>(); } } From this I derive a class and specify a template parameter to the base class class DClass : BClass<int> { } A problem occurs when I try to use the static method to create an instance of D class Program { static void Main(string[] args) { DClass d = DClass.Create(); } } Gives a compiler error "Cannot implicitly convert type 'Test.BClass<int ' to 'Test.DClass'." Adding the below cast leads to a runtime casting exception. DClass d = (DClass)DClass.Create(); Is there any succint way to allow the static method to create instances of the derived class? Ideally I would like the equivalent of a c++ typedef and I don't want the below syntax (which does work). BClass<int> d = DClass.Create();

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  • C# program for finding how many numbers are devidable by 5 in give range

    - by user1639735
    My task is: Write a program that reads two positive integer numbers and prints how many numbers p exist between them such that the reminder of the division by 5 is 0 (inclusive). Example: p(17,25) = 2. Console.Write("Enter min: "); int min = int.Parse(Console.ReadLine()); Console.Write("Enter max: "); int max = int.Parse(Console.ReadLine()); Console.WriteLine("The numbers devidable by 5 without remainder from {0} to {1} are: ",min,max); for (int i = min; i <= max; i++) { if (i % 5 == 0) { Console.WriteLine(i); } } This prints out the numbers that are devidable by 5 in the range...How do I count how many are there and print the count in the console? Thanks.

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  • How do I create a view with a picker on the bottom and a table view on the top?

    - by Andy
    Hi - first time asker, long-time lurker. I am trying to create an iPhone view that has a date/time picker on the bottom half of the screen, and a grouped, single-section, four-row table view on the top half of the screen (almost identical to the one Apple shows in Fig. 2-4 of their View Controller Programming Guide (but then never goes on to explain). Conceptually, I think I understand that what I need is a main view with a pair of subviews - one for the picker, and one for the table view. I'm pretty sure I can make the picker function once I have it on-screen, and I'm pretty sure I can make the table view function too. What I can't for the life of me figure out is how, programmatically speaking, to get the two views onto the screen simultaneously. I can lay it out perfectly in Interface Builder, but then it all goes to hell when I switch to Xcode...the view appears with the picker, but no table view. Thanks, in advance, for any help you can offer.

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  • Do we really need a safe release macro?

    - by Ian1971
    Quite a lot of people seem to use a macro such as #define SAFE_RELEASE(X) [X release]; X = nil; (myself included). I've been reassessing why I am using it and wanted to canvas some opinion. The purpose (I think) for using this macro is so that if you were to accidentally use your object after releasing it then you won't get a bad access exception because objective-c will quite happily ignore it when the object is nil. It strikes me that this has the potential to mask some obscure bugs. Maybe it would actually be preferable for the program to crash when you try to use X again. That way during testing you can find the issue and improve the code. Does this macro encourage lazy programming? Thoughts?

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  • How to reset lstset settings for listings?

    - by drittesbinom
    At the top of my tex document, I set my sourcecode listing format by \lstset{language=java} \lstset{numbers=left, numberstyle=\tiny, numbersep=5pt, breaklines=true} \lstset{emph={square}, emphstyle=\color{red}, emph={[2]root,base}, emphstyle={[2]\color{blue}}} because I merely list Java source code. At one point in my document, I had to reformat for a single listing by \lstset{commentstyle=\footnotesize\textit} \lstset{basicstyle=\ttfamily\fontsize{11}{12}\selectfont} \lstset{literate= {!=} {$\neq$}{2}} Now I have the problem that my previous Java formatting for listings is destroyed, and I dont know how to reset the lst settings to default. How can this be avoided?

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  • Can I turn off implicit Python unicode conversions to find my mixed-strings bugs?

    - by Tal Weiss
    When profiling our code I was surprised to find millions of calls to C:\Python26\lib\encodings\utf_8.py:15(decode) I started debugging and found that across our code base there are many small bugs, usually comparing a string to a unicode or adding a sting and a unicode. Python graciously decodes the strings and performs the following operations in unicode. How kind. But expensive! I am fluent in unicode, having read Joel Spolsky and Dive Into Python... I try to keep our code internals in unicode only. My question - can I turn off this pythonic nice-guy behavior? At least until I find all these bugs and fix them (usually by adding a u'u')? Some of them are extremely hard to find (a variable that is sometimes a string...). Python 2.6.5 (and I can't switch to 3.x).

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  • Need help for this syntax: "#define LEDs (char *) 0x0003010"

    - by Noge
    I'm doing programming of a softcore processor, Nios II from Altera, below is the code in one of the tutorial, I manage to get the code working by testing it on the hardware (DE2 board), however, I could not understand the code. #define Switches (volatile char *) 0x0003000 #define LEDs (char *) 0x0003010 void main() { while (1) *LEDs = *Switches; } What I know about #define is that, it is either used to define a constant, or a macro, but why in the above code, there are casting like, (char *) 0x0003010, in #define? why the 2 constants, Switches and LEDs act like a variable instead of a constant? Thanks in advance !

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  • habtm multiple times with the same model

    - by Ermin
    I am trying to model a publications. A publication can have multiple authors and editors. Since it is possible that one person is an author of one publication and an editor of another, no separate models for Authors and Editors: class Publication < ActiveRecord::Base has_and_belongs_to_many :authors, :class_name=>'Person' has_and_belongs_to_many :editors, :class_name=>'Person' end The above code doesn't work, because it uses the same join table. Now I now that I can specify the name of the join table, but there is a warning in the API documentation is a warning about that which I don't understand: :join_table: Specify the name of the join table if the default based on lexical order isn’t what you want. WARNING: If you’re overwriting the table name of either class, the table_name method MUST be declared underneath any has_and_belongs_to_many declaration in order to work.

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  • Different return value of an overridden class

    - by Samer Afach
    I have a simple but confusing question here. Is it legal to have a different return value type for overridden methods than the abstact ones defined in the base class?? I did that and the compiler didn't complain... could someone please explain? class MyBaseClass { int value; public: virtual int getValue() = 0; }; class MyClass : public MyBaseClass { double value; public: virtual double getValue(); // here!!! return is double, not int }; double MyClass::getValue() { return this->value; } The compiler totally accepted something similar (MSVC und MinGW)... could anyone please exaplain to what extent this is legal?

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  • How to print an isosceles triangle

    - by Steve
    Hello, I'm trying to learn programming by myself, I'm working from a book that has the following problem which I can't solve: Allow the user to input two values: a character to be used for printing an isosceles triangle and the size of the peak for the triangle. For example, if the user inputs # for the character and 6 for the peak, you should produce the following display: # ## ### #### ##### ###### ##### #### ### ## # This is the code I've got so far: char character; int peak; InputValues(out character, out peak); for (int row = 1; row < peak * 2; row++) { for (int col = 1; col <= row; col++) { Console.Write(character); } Console.WriteLine(); } Console.Read() // hold console open Thanks in advance.

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  • iPhone write to file (alternative directory)

    - by strider2k
    New to iPhone 3.2, Apple introduced File-Sharing support. Details can be found at https://developer.apple.com/iphone/library/releasenotes/General/WhatsNewIniPhoneOS/Articles/iPhoneOS3_2.html#//apple_ref/doc/uid/TP40009337-SW1 . Now, most examples floating around in the web demonstrates writing to the documents directory. What if I want to write files from my app but I don't want the user to be able to see it via iTunes? I'm looking at the Files and Networking section of the iPhone OS Programming Guide and I'm unsure what would be a good alternative to the documents directory for writing files to hide from the user and not be rejected by Apple's review team.

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  • Zend_Form and Liskov Substitution Principle

    - by blockhead
    A very common pattern I see (I'm picking on Zend Framework, only because I was dealing with it at the moment of this question), is something like this: class My_Form extends Zend_Form { public function init() { $this->addElement(); } } Zend_Form is not an abstract class, but is perfectly usable on its own. This seems to be "recommended" as place to "encapsulate" your forms into a nice class. Does this violate the Liskov Substitution Principle? Each subclass of Zend_Form will have a wildy different behavior than the base class. Would it be better to use composition for this, or am I totally misunderstanding this principle?

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  • JSF tags not being rendered as HTML

    - by Toto
    I'm following the Java EE firstcup tutorial using Netbeans and Glassfish. When I execute the JSF web tier I've been instructed to code, the browser gets the same JSF markup coded in the .xhtml file, and the tags are not rendered as HTML tags. I know this by using the view source code in my browser. For example, for this code: <html xmlns="http://www.w3.org/1999/xhtml" xmlns:f="http://java.sun.com/jsf/core" xmlns:h="http://java.sun.com/jsf/html"> <h:head> <title>Page title here</title> </h:head> <h:body> <h2> <h:outputText value="#{bundle.WelcomeMessage}" /> </h2> </h:body> </html> The browser should get something like: <html ...> <head> <title>Page title here</title> </head> <body> <h2> the welcome message goes here </h2> </body> </html> Right? Well, my browser is getting jsf code (the first piece of code above) and not the html code (the second piece of code above). It seems to be a configuration problem in netbeans or glassfish but don't know what. Any ideas? This is my web.xml file: <?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <context-param> <param-name>javax.faces.PROJECT_STAGE</param-name> <param-value>Development</param-value> </context-param> <servlet> <servlet-name>Faces Servlet</servlet-name> <servlet-class>javax.faces.webapp.FacesServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>Faces Servlet</servlet-name> <url-pattern>/firstcup/*</url-pattern> </servlet-mapping> <session-config> <session-timeout> 30 </session-timeout> </session-config> <welcome-file-list> <welcome-file>greetings.xhtml</welcome-file> </welcome-file-list> </web-app> This is my faces-config.xml file: <?xml version='1.0' encoding='UTF-8'?> <!-- =========== FULL CONFIGURATION FILE ================================== --> <faces-config version="2.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd"> <application> <resource-bundle> <base-name>firstcup.web.WebMessages</base-name> <var>bundle</var> </resource-bundle> <locale-config> <default-locale>en</default-locale> <supported-locale>es</supported-locale> </locale-config> </application> <navigation-rule> <from-view-id>/greetings.xhtml</from-view-id> <navigation-case> <from-outcome>success</from-outcome> <to-view-id>/response.xhtml</to-view-id> </navigation-case> </navigation-rule> </faces-config> Moreover: The url I'm entering in the browser is http://localhost:8081/firstcup/ but I've also tried: http://localhost:8081/firstcup/greetings.xhtml I've checked Glassfish logs and there's no information about not being able to load FacesServlet

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  • Do I still have to implement a singleton class by hand in .net, even when using .Net4.0?

    - by Hamish Grubijan
    Once the singleton pattern is understood, writing subsequent singleton classes in C# is a brainless exercise. I would hope that the framework would help you by providing an interface or a base class to do that. Here is how I envision it: public sealed class Schablone : ISingleton<Schablone> { // Stuff forced by the interface goes here // Extra logic goes here } Does what I am looking for exist? Is there some syntactic sugar for constructing a singleton class - whether with an interface, a class attribute, etc.? Can one write a useful and bullet-proof ISingleton themselves? Care to try? Thanks!

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  • Finding the angle of a fleeing dodo.

    - by donthackmyacc
    I'm coding some critter AI for a game i am working on for my Unity 3D project. I have no programming background and have been stumbling through this using tutorials and other peoples scripts. My problem is that i want my critter to run directly away from the player when the player kicks it. I need the dodo to run directly away from the player when kicked, and i dont know the math nor the syntax to calculate that angle. They are two characters moving independently through worldspace. Here is what i got so far: waypoint = (fleeWP.transform.position); transform.LookAt(Vector3(waypoint.x, transform.position.y, waypoint.z)); transform.Translate (Vector3.forward * speed * Time.deltaTime); This currently makes the critter move towards the waypoint, rather than away. I might be attacking this all wrong. Please chastise me.

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  • Rewriting usort function because of fatal error (PHP bug)

    - by Lionel
    The two following usort functions throw fatal error Base lambda function for closure not found in our productive environment (PHP 5.4). This seems to be a known PHP bug that should be fixed by now (https://bugs.php.net/bug.php?id=52144), but it still occurs for us. Anyway, we unfortunately don't have time to figure out what's wrong with our PHP configurations etc. We would like to rewrite these two functions without the use of anonymous functions, so that the error doesn't occur anymore. Ordering of a multidimensional array ($array) by value of key "position": usort($array, function($a, $b) { return $a['position'] - $b['position']; }); Ordering of a multidimensional array ($array) according to the order of a second array ($position_order): usort($array, function($a, $b) use($position_order) { return (isset($position_order[$a['ftid']]) ? ($position_order[$a['ftid']] - $position_order[$b['ftid']]) : 1); }); Especially the latter causes some headache, as we don't know how to pass the "outside" array $position_order.

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  • CGAL replacement for iOS

    - by Aleks N.
    I have a set of nodes that define streets. Each node has latitude and longitude. Also I have user location with latitude and longitude. My intention is to build Voronoi diagram for segments defined by each pair of nodes, and then find which node user location is closest to. Looks like this task can be accomplished with CGAL library. While I'm in the process of compiling it for iOS environment, probably you guys will be able to give links to libs that are already compiled against iOS, or were intended to be used in Objective C environment from the very beginning... Because I'm afraid that even if CGAL compiles for me, I might get into trouble when using it. Thanks!

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  • Javascript / Flash : When exactly are flash external callback methods triggered ?

    - by felace
    I have a flash application using callbacks to javascript functions (eg. when it receives some data over a socket, it'll call a js script which would change the content of a div according to that given data). Afaik, there is no actual mutual exclusion in javascript so I'm not sure if I can/need to simulate something like : callbackFunc() { lock(mutex1) foo unlock(mutex1) } ... someOtherFunc() { lock(mutex1) bar unlock(mutex1) } So, the question is, when are those callbacks called ? Are they simply queued to be executed right after the browser finishes its task or are they triggered randomly ?

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  • How to make a cell of TAdvStringGrid editable?

    - by ammu
    I am trying to implement a filter using the component TAdvStringGrid. My requirement is that I want the first row of this component to be editable when double clicked, so that the user can filter data. Borland C++ Builder is used to help achieve this task. I found this event OnCanEditCell. TCanEditCellEvent = procedure (Sender:TObject;Arow,Acol:longint;var canedit:boolean) of object; Within this function I've set canedit = true. This doesn't seem to work. Probably I need to do something more. I am new to Windows and GUI development. So any help would be great. Do I need to call this function from the OnDblClickCell event? How can I get it working? Thanks in advance

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  • Write a function in c that includes the following sequence of statements [Wont Compile]

    - by Cody
    There is a question in my programming languages textbook that is as follows: Write a C function that includes the following sequence of statements: x = 21; int x; x = 42; Run the program and explain the results. Rewrite the same code in C++ and Java and compare the results. I have written code, and played with it in all three languages but I can not even get it to compile. This includes declaring x above the three lines as well as in the calling function (as this question is obviously attempting to illustrate scoping issues) I'd like to explain the results and do the comparisons on my own, as it is an assignment question but I was wondering if anyone had any insight as to how to get this code to compile? Thanks

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  • Bash variable kills script execution

    - by Kyle Terry
    Sorry if this is better suited at serverfault, but I think it learns more towards the programming side of things. I have some code that's going into /etc/rc.local to detect what type of touch screen monitor is plugged in and changes out the xorg.conf before launching X. Here is a small snippet: CURRENT_MONITOR=`ls /dev/usb | grep 'egalax_touch\|quanta_touch'` case $CURRENT_MONITOR in '') CURRENT_MONITOR='none' ;; esac If one of those two touch screens is plugged in, it works just fine. If any other monitor is plugged in, it stops at the "CURRENT_MONITOR=ls /dev/usb | grep 'egalax_touch\|quanta_touch'." For testing I touched two files. One before creating CURRENT_MONITOR and one after CURRENT_MONITOR and only file touched before is created. I'm not a bash programmer so this might be something very obvious.

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  • VB.NET: Force user to use the topmost form

    - by SiliconCelery
    I'm programming a Minesweeper clone in Visual Studio 2010, with VB.NET, as a Windows Form Application, and I'm having trouble with the Game Won and Game Lost forms. When I show those forms, I want the game form to still be visible, so that the player can see where the mines were, but I don't want the game form to be enabled until the Game Won or Game Lost form is closed. Exactly like Windows Minesweeper does when you win or lose. There aren't any obvious properties for this, as far as I can see, and I've had no luck Googling, I don't know what terms to search. Any help is appreciated, thanks.

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  • Best datastructure for frequently queried list of objects

    - by panzerschreck
    Hello, I have a list of objects say, List. The Entity class has an equals method,on few attributes ( business rule ) to differentiate one Entity object from the other. The task that we usually carry out on this list is to remove all the duplicates something like this : List<Entity> noDuplicates = new ArrayList<Entity>(); for(Entity entity: lstEntities) { int indexOf = noDuplicates.indexOf(entity); if(indexOf >= 0 ) { noDuplicates.get(indexOf).merge(entity); } else { noDuplicates.add(entity); } } Now, the problem that I have been observing is that this part of the code, is slowing down considerably as soon as the list has objects more than 10000.I understand arraylist is doing a o(N) search. Is there a faster alternative, using HashMap is not an option, because the entity's uniqueness is built upon 4 of its attributes together, it would be tedious to put in the key itself into the map ? will sorted set help in faster querying ? Thanks

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  • Creating OpenSocial container for ASP.NET Site

    - by Admin
    hello, i run a social networking site written in asp.net and would like to open it to developers using the OpenSocial APIs. I have read information on opensocial.org as well as google's opensocial page and have a basic idea what it takes but still there is a lot of info missing to even get started. I know i gotta provide RESTful API as well as JavaScript API, authenticating using OAuth methods. Does my container has to provide all 3: JSON, XML, and AtomPub representations of data? I found Shindig but it runs under Apache, i need something for IIS. Are there any libraries that i could use as a base for my APIs to save time? Is it even recommended to write the entire container from scratch? thanks

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  • Wanting a type of grid for a pixel editor

    - by wiggles
    Hi, I am currently trying to develop a basic pixel editor application to build up my programming experience with Java. I am designing it so the user has several colour options on, they click on an option and then they can drag over the cells in the grid and they change colour (like a typical image editor, but with a sort of snap on to each grid cell) Any idea of what Java component, if any, is able to implement this type of grid in Java? I had thought of each cell being a JButton, but this seemed terribly inefficient and I don't think it would be possible to change the colour of each cell(button) with out individually clicking on each one. Any help appreciated.

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