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  • Core Data and BOOL setup

    - by John Valen
    I am working on an app that uses Core Data as its backend for managing SQLite records. I have everything working with strings and numbers, but have just tried adding BOOL fields and can't seem to get things to work. In the .xcdatamodel, I have added a field to my object called isCurrentlyForSale which is not Optional, not Transient, and not Indexed. The attribute's type is set to Boolean with default value NO. When I created the class files from the data model, the boilerplate code added for this property in the .h header was: @property (nonatomic, retain) NSNumber * isCurrentlyForSale; along with the @dynamic isCurrentlyForSale; in the .m implementation file. I've always worked with booleans as simple BOOLs. I've read that I could use NSNumber's numberWithBool and boolValue methods, but this seems like an aweful lot of extra code for something so simple. Can the @property in the header be changed to a simple BOOL? If so is there anything to watch out for? Thanks -John

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  • Adding and altering multiple text items to a Canvas -- what approach?

    - by philologon
    I am attempting to use a Canvas to create a simple Cad application. I have been able to get lines to draw as I want. For now the only other thing I need is text. The user should be able to edit the text in place. ?Is one of these better to use for this over the others? Rich Text TextBlock TextBox Label A more important question, though, is once I have chosen which class to use for implementation, how do I set and get the text value in code? Since the app is in essence a cad application, text will be added, deleted, and altered often, so I am not attempting to put these in XAML, but code-behind. That is why I am asking about how to do this in code. If the answer is "use X.SetValue()" (or that family of methods), then please tell me what I am supposed to do with the required DependencyProperty reference? TIA. Paul

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  • Custom tag with the logic in JSP (interprets JSPs with the passed parameters)

    - by Romario
    I want to create a custom jsp tag. I want this tag to take a jsp file as a parameter, and in this jsp I want to write the whole logic of the tag. Let's say I want to pass a collection to a tag and then I would write code in jsp to iterate the collection and display it in . Why I want to do it - I really hate having out.print() in my code. Is something like this feasible? I remember doing something similar a while ago, I just forgot the details and my search doesn't seem to find relevant info - a link to a good implementation of the would be nice.

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  • C# dependency injection - how to you inject a dependency without source?

    - by Phil Harris
    Hi, I am trying to get started with some simple dependency injection using C# and i've run up against an issue that I can't seem to come up with an answer for. I have a class that was written by another department for which I don't have the source in my project. I wanted to inject an object of this type though a constructor using an interface, but of course, i can't change the injected objects implementation to implement the interface to achieve polymorphism when casting the object to the interface type. Every academic example I have ever seen of this technique has the classes uses classes which are declared in the project itself. How would I go about injecting my dependency without the source being available in the project? I hope that makes sense, thanks.

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  • What's a good way to detect wrap-around in a fixed-width message counter?

    - by Kristo
    I'm writing a client application to communicate with a server program via UDP. The client periodically makes requests for data and needs to use the most recent server response. The request message has a 16-bit unsigned counter field that is echoed by the server so I can pair requests with server responses. Since it's UDP, I have to handle the case where server responses arrive out of order (or don't arrive at all). Naively, that means holding on to the highest message counter seen so far and dropping any incoming message with a lower number. But that will fail as soon as we pass 65535 messages and the counter wraps back to zero. Is there a good way to detect (with reasonable probability) that, for example, message 5 actually comes after message 65,000? The implementation language is C++.

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  • How to implement square root and exponentiation on arbitrary length numbers?

    - by tomp
    I'm working on new data type for arbitrary length numbers (only non-negative integers) and I got stuck at implementing square root and exponentiation functions (only for natural exponents). Please help. I store the arbitrary length number as a string, so all operations are made char by char. Please don't include advices to use different (existing) library or other way to store the number than string. It's meant to be a programming exercise, not a real-world application, so optimization and performance are not so necessary. If you include code in your answer, I would prefer it to be in either pseudo-code or in C++. The important thing is the algorithm, not the implementation itself. Thanks for the help.

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  • ICOmmand - canexecute can not disable Button with image content.

    - by Anish
    Hi , I have a button control in my wpf-mvvm application. I use an ICommand property (defined in viewmodel) to bind the button click event to viewmodel. I have - execute and canexecute parameters for my ICommand implementation (RelayCommand). Even if CanExecute is false...button is not disabled...WHEN button CONTENT is IMAGE But, when button content is text..enable/disable works fine. <Button DockPanel.Dock="Top" Command="{Binding Path=MoveUpCommand}"> <Button.Content> <Image Source="/Resources/MoveUpArrow.png"></Image> </Button.Content> <Style> <Style.Triggers> <Trigger Property="IsEnabled" Value="False"> <Setter Property="Opacity" Value=".5" /> </Trigger> </Style.Triggers> </Style> </Button>

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  • Rails 3 respond_to: default format?

    - by bdorry
    I am converting a Rails 2 application to Rails 3. I currently have a controller set up like the following: class Api::RegionsController < ApplicationController respond_to :xml, :json end with and an action that looks like the following: def index @regions = Region.all respond_with @regions end The implementation is pretty straightforward, api/regions, api/regions.xml and api/regions.json all respond as you would expect. The problem is that I want api/regions by default to respond via XML. I have consumers that expect an XML response and I would hate to have them change all their URLs to include .xml unless absolutely necessary. In Rails 2 you would accomplish that by doing this: respond_to do |format| format.xml { render :xml => @region.to_xml } format.json { render :json => @region.to_json } end But in Rails 3 I cannot find a way to default it to an XML response. Any ideas?

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  • What are these lines doing?

    - by Montecristo
    I'm starting learning javascript for a project, I've found a script that does a part of what I need to do, I'd like to know how it works, both for me and in case it needs to be modified. Originally it was used inside the page, now I've put it in a file on its own and does not work anymore, so I'm dividing it in parts, because I fail to get the whole thing. Here is what bother me most for now: 1) Is this a declaration a function? What is its name? How can it be invoked? (function() { //some code })(); 2) No clue of what is going on here var VARIABLE = VARIABLE || {}; 3) Am I defining a the implementation of methodCall here? Something like overriding a method in Java? VARIABLE.methodCall = function(parameter) { console.log("parameter was: " + parameter); }; Thank you in advance for your help.

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  • Why should I use MVVM when it breaks built in functionality

    - by Jakob
    I'm struggling to grasp why MVVM is really a good pattern to implement in riaserivces, To me there's nothing but trouble to it, it just add's another tier that I have to code. I Get that I could change the UI, but really I don't need to. Instead i won't be able to user out of the box functionality with riaservices, datagrid, dataform all controls require some implementation. Why can't it just be simple? Is there really no way to get MVVM to automatically set "IsBusy" and all the dataform edit functionality. It's like reinventing the wheel to me, and it seems that I'd be able to write code much faster just using riaservices

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  • How to make Visual C++ 9 not emit code that is actually never called?

    - by sharptooth
    My native C++ COM component uses ATL. In DllRegisterServer() I call CComModule::RegisterServer(): STDAPI DllRegisterServer() { return _Module.RegisterServer(FALSE); // <<< notice FALSE here } FALSE is passed to indicate to not register the type library. ATL is available as sources, so I in fact compile the implementation of CComModule::RegisterServer(). Somewhere down the call stack there's an if statement: if( doRegisterTypeLibrary ) { //<< FALSE goes here // do some stuff, then call RegisterTypeLib() } The compiler sees all of the above code and so it can see that in fact the if condition is always false, yet when I inspect the linker progress messages I see that the reference to RegisterTypeLib() is still there, so the if statement is not eliminated. Can I make Visual C++ 9 perform better static analysis and actually see that some code is never called and not emit that code?

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  • Basic Client-Server Design for persistent connections?

    - by cam
    Here's as far as I understand it: Client & Server make connection Client sends server data Server interprets data, sends client data So on, and so forth, until client sends disconnect signal. I'm just wondering about implementation. Step 2 and 3 are confusing to me, maybe I'm over-complicating it. Is there anymore to interpreting the data than a giant switch statement? Any good books on client/server design? Specifically talking about multithreaded servers, scalability, and message design (byte 1 = header info, byte 2 = blah blah, etc)? Specifically geared towards C++.

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  • C++ Beginner - Best way to read 3 consecutive values from the command line?

    - by Francisco P.
    Hello everyone, I am writing a text-based Scrabble implementation for a college project. The specification states that the user's position input must be read from single line, like this: Coordinates of the word's first letter and orientation (<A – P> <1 – 15> <H ou V>): G 5 H G 5 H is the user's input for that particular example. The order, as shown, must be char int char. What is the best way to read the user's input? cin >> row >> column >> orientation will cause crashes if the user screws up. A getline and a subsequent string parser are a valid solution, but represent a bit of work. Is there another, better, way to do this, that I am missing? Thanks for your time!

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  • drawImage in Java applet flickers in Safari

    - by lcvinny
    I'm having a flicker problem in a Java applet in Safari (Mac). However, it's not the usual double buffering problem. I have isolated it down to one single drawImage call (no redundant repaint, no clear is called), which gives a white flicker before painting the image but not on every repaint. In fact, I measured the duration of the drawImage call, which is normally about 1ms, but up to 30ms about every 5th time paint is called, which is when it flickers. Repaints are triggered when I drag a component or when the window is scrolled. Is this a bug in the java implementation on OSX, and is there a fix for it?

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  • Why do C++ streams use char instead of unsigned char?

    - by Johannes Schaub - litb
    I've always wondered why the C++ Standard library has instantiated basic_[io]stream and all its variants using the char type instead of the unsigned char type. char means (depending on whether it is signed or not) you can have overflow and underflow for operations like get(), which will lead to implementation-defined value of the variables involved. Another example is when you want to output a byte, unformatted, to an ostream using its put function. Any ideas? Note: I'm still not really convinced. So if you know the definitive answer, you can still post it indeed.

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  • save and play recorded sound

    - by blacksheep
    i'd like to save and play again this recorded sounds: @interface Recorder : NSObject { NSMutableArray *times; NSMutableArray *samples; } @end @implementation Recorder – (id) init { [super init]; times = [[NSMutableArray alloc] init]; samples = [[NSMutableArray alloc] init]; return self; } – (void) recordSound: (id) someSound { CFAbsoluteTime now = CFAbsoluteTimeGetCurrent(); NSNumber *wrappedTime = [NSNumber numberWithDouble:now]; [times addObject:wrappedTime]; [samples addObject:someSound]; } @end thanx blacksheep

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  • Java, how to trace functions called

    - by user435657
    Hi all, I want to trace the beginning [& ending] of functions called in Java, like the following code: public void foo() { System.out.println("begin of foo()"); ... System.out.println("e-n-d of foo()"); } But maintaining of the dump code System.out.println is something tedious and error-prone, for there may be tens of thounds of function in an class. Any good idea can ease this work? I don't want dump statements all over the file. Implementation of both or one of the beginning & ending traces is perferd. But, if impossible, recordings of that the function has been called is also helpful. I mean not care the exact beginnig and ending, just tell that the function has been called.

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  • WPF - How do I style a row based on a binding property value?

    - by Nick
    Hey! So I am trying to bind a collection of objects (IList<) to a WPF datagrid. I would like to make the row background a different color if the 'artist' property is null or empty. I am checking the value stored at the property on the LoadingRow datagrid event. Currently my implementation seems to style all of the rows with an empty or null 'artist' property correctly. The problem is that is also styles the rows where the property is not null or empty in some cases. So some rows are given the red background even though the rows 'artist' property is not null. Can anyone tell me why this could be?? Here is the LoadingRow event: private void trackGrid_LoadingRow(object sender, DataGridRowEventArgs e) { Track t = e.Row.DataContext as Track; if (String.IsNullOrEmpty(t.Artist)) { e.Row.Background = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromArgb(255, 255, 125, 125)); } }

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  • I need to generate credit card surrogates (tokens) that are format preserving.

    - by jammer59
    For an eCommerce application I need to take a credit card and use the real card for passing through to a payment gateway but I need to store, and return to the transaction initiator, a surrogate that is format preserving. Specifically, this means: 1) The number of digits in the surrogate is the same as the real card number (PAN). 2) The issuer type part of the card -- the initial 1,2 or 4 digits remains the same in the surrogate as in the original PAN. 3) The final 4 digits of the surrogate remain the same (for customer service purposes.) 4) The surrogate passes the Luhn mod10 check for a syntactially valid credit card. I can readily handle requirements 1-3 but #4 has me completely stumped! The final implementation will be either t-sql or c#. Any ideas?

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  • Interrupting `while loop` with keyboard in Cython

    - by linello
    I want to be able to interrupt a long function with cython, using the usual CTRL+C interrupt command. My C++ long function is repeatedly called inside a while loop from Cython code, but I want to be able, during the loop, to send an "interrupt" and block the while loop. The interrupt also should wait the longFunction() to finish, so that no data are lost or kept in unknown status. This is one of my first implementation, which obviously doesn't work: computed=0; print "Computing long function..." while ( computed==0 ): try: computed = self.thisptr.aLongFunction() except (KeyboardInterrupt, SystemExit): computed=1 print '\n! Received keyboard interrupt.\n' break; (p.s. self.thisptr is the pointer to the current class which implements aLongFunction() )

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  • Efficient alternatives to merge for larger data.frames R

    - by Etienne Low-Décarie
    I am looking for an efficient (both computer resource wise and learning/implementation wise) method to merge two larger (size1 million / 300 KB RData file) data frames. "merge" in base R and "join" in plyr appear to use up all my memory effectively crashing my system. Example load test data frame and try test.merged<-merge(test, test) or test.merged<-join(test, test, type="all") - The following post provides a list of merge and alternatives: How to join data frames in R (inner, outer, left, right)? The following allows object size inspection: https://heuristically.wordpress.com/2010/01/04/r-memory-usage-statistics-variable/ Data produced by anonym

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  • If .net sha1 hash expects a byte array, and php sha1() wants a string, can I match the results?

    - by lynn
    I have a set of bytes I want to apply an sha1 hash to. One hash will be in .net, the other in PHP. Then I'll test to see if they match. In .net, you can create a byte array and use sha.ComputeHash(). byte[] data = new byte[DATA_SIZE]; byte[] result; SHA1 sha = new SHA1CryptoServiceProvider(); // This is one implementation of the abstract class SHA1. result = sha.ComputeHash(data); In PHP, you call sha1($string). I can't do anything about the .net side of the code, but how can I get the same hash out of PHP that .net will generate? Please note: I am ONLY able to work on the PHP side of this. The .net stuff is fixed and can't be modified. Thanks!

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  • Hiding an internal interface in a "friend" assembly

    - by dmo
    I have two assemblies: A and B. A has InternalsVisibleTo set for B. I would like to make calls from A to get information that can only be known by a type defined in B in a way that keeps things internal. I can do this using an internal interface defined in A and implemented explicitly in B. Assembly A internal interface IHasData { Data GetData(); } class ClassA { DoSomething(IHasData); } Assembly B public abstract class ClassB : IHasData { Data IHasData.GetData() { /** do something internal **/ } } The trouble comes when someone references assembly B and derives from ClassB - they get the error: "The type 'AssemblyA.IHasData' is defined in an assembly that is not referenced" even though that type should be invisible to them. If I look at the public type definition I see what I expect - ClassB with no interfaces implemented. Why do I get this error? All of the implementation is in assembly B. I could use IHasData internally in ClassB and that wouldn't require assembly A to be referenced. Can someone help me understand what is going on?

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  • I'm new to C++. Please Help me with the Linked List (What functions to add)?

    - by Igal
    DEAR All; Hi, I'm just beginner to C++; Please help me to understand: What functions should be in the Linked list class ? I think there should be overloaded operators << and ; Please help me to improve the code (style, errors, etc,) Thanks for advance. Igal. Please review the small code for the integer List (enclosed MyNODE.h and ListDriver1.cpp); MyNODE.h // This is my first attempt to write linked list. Igal Spector, June 2010. #include <iostream.h> #include <assert.h> //Forward Declaration of the classes: class ListNode; class TheLinkedlist; // Definition of the node (WITH IMPLEMENTATION !!!, without test drive): class ListNode{ friend class TheLinkedlist; public: // constructor: ListNode(const int& value, ListNode *next= 0); // note: no destructor, as this handled by TheLinkedList class. // accessor: return data in the node. // int Show() const {return theData;} private: int theData; //the Data ListNode* theNext; //points to the next node in the list. }; //Implementations: //constructor: inline ListNode::ListNode(const int &value,ListNode *next) :theData(value),theNext(next){} //end of ListNode class, now for the LL class: class TheLinkedlist { public: //constructors: TheLinkedlist(); virtual ~TheLinkedlist(); // Accessors: void InsertAtFront(const &); void AppendAtBack(const &); // void InOrderInsert(const &); bool IsEmpty()const;//predicate function void Print() const; private: ListNode * Head; //pointer to first node ListNode * Tail; //pointer to last node. }; //Implementation: //Default constructor inline TheLinkedlist::TheLinkedlist():Head(0),Tail(0) {} //Destructor inline TheLinkedlist::~TheLinkedlist(){ if(!IsEmpty()){ //list is not empty cout<<"\n\tDestroying Nodes"<<endl; ListNode *currentPointer=Head, *tempPtr; while(currentPointer != 0){ //Delete remaining Nodes. tempPtr=currentPointer; cout<<"The node: "<<tempPtr->theData <<" is Destroyed."<<endl<<endl; currentPointer=currentPointer->theNext; delete tempPtr; } Head=Tail = 0; //don't forget this, as it may be checked one day. } } //Insert the Node to the beginning of the list: void TheLinkedlist::InsertAtFront(const int& value){ ListNode *newPtr = new ListNode(value,Head); assert(newPtr!=0); if(IsEmpty()) //list is empty Head = Tail = newPtr; else { //list is NOT empty newPtr->theNext = Head; Head = newPtr; } } //Insert the Node to the beginning of the list: void TheLinkedlist::AppendAtBack(const int& value){ ListNode *newPtr = new ListNode(value, NULL); assert(newPtr!=0); if(IsEmpty()) //list is empty Head = Tail = newPtr; else { //list is NOT empty Tail->theNext = newPtr; Tail = newPtr; } } //is the list empty? inline bool TheLinkedlist::IsEmpty() const { return (Head == 0); } // Display the contents of the list void TheLinkedlist::Print()const{ if ( IsEmpty() ){ cout << "\n\t The list is empty!!"<<endl; return; } ListNode *tempPTR = Head; cout<<"\n\t The List is: "; while ( tempPTR != 0 ){ cout<< tempPTR->theData <<" "; tempPTR = tempPTR->theNext; } cout<<endl<<endl; } ////////////////////////////////////// The test Driver: //Driver test for integer Linked List. #include <iostream.h> #include "MyNODE.h" // main Driver int main(){ cout<< "\n\t This is the test for integer LinkedList."<<endl; const int arraySize=11, ARRAY[arraySize]={44,77,88,99,11,2,22,204,50,58,12}; cout << "\n\tThe array is: "; //print the numbers. for (int i=0;i<arraySize; i++) cout<<ARRAY[i]<<", "; TheLinkedlist list; //declare the list for(int index=0;index<arraySize;index++) list.AppendAtBack( ARRAY[index] );//create the list cout<<endl<<endl; list.Print(); //print the list return 0; //end of the program. }

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  • casting a generic array in java

    - by liloboy
    The implementation is for a linked list in java : public AnyType[] toArr() { AnyType[] arr = (AnyType[]) new Object[size]; int i = 0; Node<AnyType> current = head.next; while (cur != head){ arr[i] = current.data;// fill the array i++; current = current.next; } return arr; } public static void main(String[] args) { System.out.println(ll.toArr().toString()); } The error that I get: Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.Integer; Thanks.

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