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  • Singletons and constants

    - by devoured elysium
    I am making a program which makes use of a couple of constants. At first, each time I needed to use a constant, I'd define it as //C# private static readonly int MyConstant = xxx; //Java private static final int MyConstant = xxx; in the class where I'd need it. After some time, I started to realise that some constants would be needed in more than one class. At this time, I had 3 choises: To define them in the different classes that needed it. This leads to repetition. If by some reason later I need to change one of them, I'd have to check in all classes to replace them everywhere. To define a static class/singleton with all the constants as public. If I needed a constant X in ClassA, ClassB and ClassC, I could just define it in ClassA as public, and then have ClassB and ClassC refer to them. This solution doesn't seem that good to me as it introduces even more dependencies as the classes already have between them. I ended up implementing my code with the second option. Is that the best alternative? I feel I am probably missing some other better alternative. What worries me about using the singleton here is that it is nowhere clear to a user of the class that this class is using the singleton. Maybe I could create a ConstantsClass that held all the constants needed and then I'd pass it in the constructor to the classes that'd need it? Thanks

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  • PyQt4 plugin in c++ application

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

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

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

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  • Strange C++ thread function invocation

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

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  • how toaccess the attributes in another form? c#

    - by Chelsea_cole
    I have a problem in a same namespace: public partial class frmForm1 : Form // Form1 { public class Account { public string Username; public string Password; } public class ListAcc { public static int count = 0; private static List<Account> UserList; public static List<Account> Data() { return UserList; } } } public partial class frmForm2 : Form // Form2 { private void button2_Click(object sender, EventArgs e) { frmForm1.Account A; string m = frmForm1.ListAcc<A>.[0].Username; //ERROR } } How could i access the attributes (Username, Password...) in frmForm1? Someone help me? Thanks!

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  • what is the reason i am getting out put is 111?

    - by kam
    Hi, #include "stdafx.h" #include<iostream.h> template<class T> class Sample { public: Sample(); static int i; }; template<class T> int Sample<T>::i = 0; template<class T> Sample<T>::Sample() { i++; cout<<i; } void main() { Sample<int>s1; Sample<float>s2; Sample<char>s3; } output: 111 what is the reason i am getting out put is 111?

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  • What to prefer in the following case?

    - by GK
    say suppose I have class as : public class Age { private int age; public int getAge() { return this.age; } } In my Main class I am calling the getAge() method many times. So I wanted to know is it advisable to call so many times or call once and assign it to some variable and use that variable. Which is best and why?

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  • Unable to .append(); without eliminating all the spaces in the code

    - by Adam
    $('#form_holder').append('<div id="spec_id_'+count+'"><div class="avail_container"> <input class="avail_fields" type="checkbox" checked="checked" name="special'+count+'" /><span class="avail_field_label">Special Date</span></div> <div class="avail_container"><div class="avail_time_container"><span class="field_label">Time</span> <select name="special'+count+'_time_from_1"> <?php for ($t = 0; $t<24; $t++){ ?> <option value="<?php echo $t; ?>"><?php echo $t; ?></option> <?php } ?> </select>: <select name="special'+count+'_time_from_2"> <?php for ($t = 0; $t<60; $t+=15){ ?> <option value="<?php if($t == 0){ echo $t . '' . $t; }else{ echo $t; } ?>"><?php if($t == 0){ echo $t . '' . $t; }else{ echo $t; } ?></option> <?php } ?> </select> <span class="field_label">to</span> <select name="special'+count+'_time_to_1"> <?php for ($t = 0; $t<24; $t++){ ?> <option value="<?php echo $t; ?>"><?php echo $t; ?></option> <?php } ?> </select>: <select name="special'+count+'_time_to_2"> <?php for ($t = 0; $t<60; $t+=15){ ?> <option value="<?php if($t == 0){ echo $t . '' . $t; }else{ echo $t; } ?>"><?php if($t == 0){ echo $t . '' . $t; }else{ echo $t; } ?></option> <?php } ?> </select> </div> </div> </div>'); I'm assuming javascript or jquery does not like breaks like I have here, because all my javascript code does not work. What would be an alternative to eliminating all the spaces, which would make viewing the code difficult?

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  • When will [MFMailComposeViewController canSendMail] return NO

    - by pythonquick
    M iPhone app is using the MFMailComposeViewController class to send an in-app email with an attachment. The app will only attempt to display the mail composer dialog if the "canSendMail" method of class MFMailComposeViewController returns true (YES). Specifically, if the following method returns YES, it shows the mail composer, otherwise the user is presented with an error alert dialog stating that there are no email accounts set up on the device: - (BOOL)canDeviceSendEmail { Class mailClass = (NSClassFromString(@"MFMailComposeViewController")); return mailClass != nil && [mailClass canSendMail]; } A team of testers have reported that they get this error alert dialog, even when email accounts are set up on the device. The tester used an iPhone 3G with OS 3.1.3. Therefore the MFMailComposeViewController class must have existed, and the "canSendMail" method must have returned NO. My question is therefore: apart from the case when there are no email accounts set up on the device, in what other circumstances can the "canSendMail" method return NO? ~ Thanks

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  • Asp.net static object behaviour

    - by Circadian
    I have the following class as part of an asp.net application. public sealed class SomeClass { private static string appId = Guid.NewGuid().ToString(); public static ReadSomethingFromDb(){} public static WriteSomethingToDb(){} } There are more than one application instances in the same application pool, and they all access the same database. I want the operations performed by the above class to be uniquely tied to the instance that performed it, hence the use of the appId. So adding a record to the database would for example contain a name, address and appId. This has been simplified for discussion purposes. Assuming that I have two instances running at mysite.a and mysite.b the above class would generate two different guids. My problem is that mysite.a sometimes produces more than one guid, which is unexpected. Thank you in advance

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

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

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  • How can I avoid huge communication classes in WCF?

    - by mafutrct
    My understanding is that all contract-implementing code has to be in a single class, that can become very large, obviously. How do I avoid this? I really prefer to have a few small classes doing one part of the communication with clients than a single behemoth class. The only idea I could think of is using multiple interfaces implemented by a single class split up by partial, but I don't this this is really solving the issue.

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  • Minimal framework in Scala for collections with inheriting return type

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

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  • Pin Control in HCS12

    - by Brian Lindsey
    A HCS12 microcontroller I had to buy for a class I had recently taken has 40 pins on the back side of it. The class was merely about computer organization, and so unfortunately, we never had a chance to cover all the capabilities of the chip itself. Now that the class is over, I have been thinking about using the to familiarize myself with the assembly language. I haven't found any sources that cover pin control and was wondering if anyone could possibly provide me with a hands-on pin tutorial.

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  • Dynamic class_name for has_many relations

    - by vooD
    I'm trying to make has_many relation with dynamic class_name attribute class Category < ActiveRecord::Base has_many :ads, :class_name => ( lambda { return self.item_type } ) end or class Category < ActiveRecord::Base has_many :ads, :class_name => self.item_type end But i got errors: can't convert Proc into String or undefined method `item_type' for #<Class:0xb62c6c88> Thank you for any help!

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  • Misunderstanding function pointer - passing it as an argument

    - by Stef
    I want to pass a member function of class A to class B via a function pointer as argument. Please advise whether this road is leading somewhere and help me fill the pothole. #include <iostream> using namespace std; class A{ public: int dosomeA(int x){ cout<< "doing some A to "<<x <<endl; return(0); } }; class B{ public: B(int (*ptr)(int)){ptr(0);}; }; int main() { A a; int (*APtr)(int)=&A::dosomeA; B b(APtr); return 0; } This brilliant piece of code leaves me with the compiler error: cannot convert int (A::*)(int)' toint (*)(int)' in initialization Firstly I want it to compile. Secondly I don't want dosomeA to be STATIC.

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  • pagination panel should remain static

    - by fusion
    i've a search form in which a user enters the keyword and the results are displayed with pagination. everything works fine except for the fact that when the user clicks on the 'Next' button, the pagination panel disappears as well when the page loads to retrieve the data through ajax. how do i make the pagination panel static, while the data is being retrieved? search.html: <form name="myform" class="wrapper"> <input type="text" name="q" id="q" onkeyup="showPage();" class="txt_search"/> <input type="button" name="button" onclick="showPage();" class="button"/> <p> </p> <div id="txtHint"></div> </form> ajax: var url="search.php"; url += "?q="+str+"&page="+page+"&list="; url += "&sid="+Math.random(); xmlHttp.onreadystatechange=stateChanged; xmlHttp.open("GET",url,true); xmlHttp.send(null); function stateChanged(){ if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete"){ document.getElementById("txtHint").innerHTML=xmlHttp.responseText; } //end if } //end function search.php: $self = $_SERVER['PHP_SELF']; $limit = 3; //Number of results per page $adjacents = 2; $numpages=ceil($totalrows/$limit); $query = $query." ORDER BY idQuotes LIMIT " . ($page-1)*$limit . ",$limit"; $result = mysql_query($query, $conn) or die('Error:' .mysql_error()); ?> <div class="search_caption">Search Results</div> <div class="search_div"> <table class="result"> <?php while ($row= mysql_fetch_array($result, MYSQL_ASSOC)) { $cQuote = highlightWords(htmlspecialchars($row['cQuotes']), $search_result); ?> <tr> . . .display results. . . </tr> <?php } ?> </table> </div> <hr> <div class="searchmain"> <?php //Create and print the Navigation bar $nav=""; $next = $page+1; $prev = $page-1; if($page > 1) { $nav .= "<a onclick=\"showPage('','$prev'); return false;\" href=\"$self?page=" . $prev . "&q=" .urlencode($search_result) . "\">< Prev</a>"; $first = "<a onclick=\"showPage('','1'); return false;\" href=\"$self?page=1&q=" .urlencode($search_result) . "\"> << </a>" ; } else { $nav .= "&nbsp;"; $first = "&nbsp;"; } for($i = 1 ; $i <= $numpages ; $i++) { if($i == $page) { $nav .= "<span class=\"no_link\">$i</span>"; }else{ $nav .= "<a onclick=\"showPage('',$i); return false;\" href=\"$self?page=" . $i . "&q=" .urlencode($search_result) . "\">$i</a>"; } } if($page < $numpages) { $nav .= "<a onclick=\"showPage('','$next'); return false;\" href=\"$self?page=" . $next . "&q=" .urlencode($search_result) . "\">Next ></a>"; $last = "<a onclick=\"showPage('','$numpages'); return false;\" href=\"$self?page=$numpages&q=" .urlencode($search_result) . "\"> >> </a>"; } else { $nav .= "&nbsp;"; $last = "&nbsp;"; } echo $first . $nav . $last; ?> </div>

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  • Create a custom button

    - by Beppi Menozzi
    Sorry if this is too basic. I created a new class that extends Button: public class MyButton extends Button { private Context ctx; public MyButton(Context context) { super(context); ctx = context; } private void click() { // DO WHAT I NEED (FOR EXAMPLE CHANGE BACKGROUND) } } How can make it possible that, when I setOnClickListener() from another class where I instantiated this object, the click() method is called automatically? Thanks.

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  • Constructor initialising an array of subobjects?

    - by ojw
    Say I have several objects within a class, each of which needs constructing with a different value. I can write something like this: class b { public: b(int num) { // 1 for a.b1, and 2 for a.b2 } }; class a { public: b b1; b b2; a() : b1(1), b2(2) { } }; However, is it possible to do the same thing if those multiple objects are stored in an array? My first attempt at it doesn't compile: class a { public: b bb[2]; a() : bb[0](1), bb[1](2) { } };

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  • Three customer addresses in one table or in separate tables?

    - by DR
    In my application I have a Customer class and an Address class. The Customer class has three instances of the Address class: customerAddress, deliveryAddress, invoiceAddress. Whats the best way to reflect this structure in a database? The straightforward way would be a customer table and a separate address table. A more denormalized way would be just a customer table with columns for every address (Example for "street": customer_street, delivery_street, invoice_street) What are your experiences with that? Are there any advantages and disadvantages of these approaches?

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  • Unable to run JAR file (created in Eclipse)

    - by Trist
    I hate starting a post with this but I'm new to Java... I've followed this tutorial to create a socket server (mines in Eclipse). I can run the server within Eclipse, all is well. But when I try to export the project I can't figure out how to run it. I keep getting this error (it varies depending on how I run it) Exception in thread "main" java.lang.NoClassDefFoundError: xsocketserver/Main Caused by: java.lang.ClassNotFoundException: xsocketserver.Main at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:315) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:330) at java.lang.ClassLoader.loadClass(ClassLoader.java:250) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:398) I've read this problem relates to class paths being set. I've tried the following: java -cp libs/xSocket-2.8.12.jar xsocketserver.Main java -jar xSocketServer.jar java -classpath xSocketServer:xSocketServer/libs/xSocket-2.8.12.jar xsocketserver.Main plus many others. The file structure within the JAR is as follows: xSocketServer.jar -> xsocketserver -> Main.class -> xSocketDataHandler.class -> META-INF -> MANIFEST.MF -> libs -> xSocket-2.8.12.jar Incidentally I've tried adding my own manifest file which contains the Class-Path but when I check it it always reads: Manifest-Version: 1.0 Main-Class: xsocketserver.Main I'm guessing this is a common problem based on the number of hits I've seen in Google but I can't fathom what I'm doing wrong. Wrong Export settings maybe??

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  • doubt in - Function Objects - c++

    - by Eternal Learner
    I have a class class fobj{ public: fobj(int i):id(i) {} void operator()() { std::cout<<"Prints"<<std::endl; } private: int id; }; template<typename T> void func(T type) { type(); } My Doubt is if I invoke func like Method 1: func(fobj(1); the message I wanted to print is printed. I was always thinking I needed to do something like Method 2: fobj Iobj(1); // create an instance of the fobj class func(Iobj); //call func by passing Iobj(which is a function object) How does Method 1 work? I mean what exactly happens? and how is a call made to the operator() in class fobj ?

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  • c++ template and its element type

    - by David
    This is my template matrix class: template<typename T> class Matrix { public: .... Matrix<T> operator / (const T &num); } However, in my Pixel class, I didn't define the Pixel/Pixel operator at all! Why in this case, the compiler still compiles?

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  • jQueryUI widget text plus icon

    - by cf_PhillipSenn
    I have: <div class="ui-widget"> <div class="ui-widget-header"> My Menu<span class="ui-icon ui-icon-circle-triangle-n"></span> </div> <ul class="ui-widget-content"> <li>Menu Item 1</li> <li>Menu Item 2</li> <li>Menu Item 3</li> </ul> </div> Right now, the ui-icon is appearing below "My Menu" Q: How can I get "My Menu" to appear on the same line as the UI widget?

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  • Java PropertyChangeListener

    - by Laphroaig
    Hi, i'm trying to figure out how to listen a property change on another class. this is my code: class with the property to listen: public class ClassWithProperty { private PropertyChangeSupport changes = new PropertyChangeSupport(this); private int usersOnline; public int getUsersOnline() { return usersOnline; } public ClassWithProperty() { usersOnline = 0; while (usersOnline<10) { changes.firePropertyChange("usersOnline", usersOnline, usersOnline++); } } public void addPropertyChangeListener( PropertyChangeListener l) { changes.addPropertyChangeListener(l); } public void removePropertyChangeListener( PropertyChangeListener l) { changes.removePropertyChangeListener(l); } } class where i need to know when the property change: public class Main { private static ClassWithProperty test; public static void main(String[] args) { test = new ClassWithProperty(); test.addPropertyChangeListener(listen()); } private static PropertyChangeListener listen() { System.out.println(test.getUsersOnline()); return null; } } I have the event fired only the last time (usersOnline=10). Sorry if it can be a stupid question, i'm learning now java and can't find a solution.

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