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  • Operator + for matrices in C++

    - by cibercitizen1
    I suppose the naive implementation of a + operator for matrices (2D for instance) in C++ would be: class Matrix { Matrix operator+ (Matrix other) const { Matrix result; // fill result with *this.data plus other.data return result; } } so we could use it like Matrix a; Matrix b; Matrix c; c = a + b; Right? But if matrices are big this is not efficient as we are doing one not-necessary copy (return result). Therefore, If we wan't to be efficient we have to forget the clean call: c = a + b; Right? What would you suggest / prefer ? Thanks.

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  • Does isolation frameworks (Moq, RhinoMock, etc) lead to test overspecification?

    - by Marius
    In Osherove's great book "The Art of Unit Testing" one of the test anti-patterns is over-specification which is basically the same as testing the internal state of the object instead of some expected output. To my experience, using Isolation frameworks can cause the same unwanted side effects as testing internal behavior because one tends to only implement the behavior necessary to make your stub interact with the object under test. Now if your implementation changes later on (but the contract remains the same), your test will suddenly break because you are expecting some data from the stub which was not implemented. So what do you think is the best approach to counter this? 1) Implement your stubs/mocks fully, this has the negative side-effect of potentially making your test less readable and also specifying more than necessary to make your test pass. 2) Favor manual, fully implemented fakes. 3) Implement your stubs/fakes so that they make your test just pass, and then deal with the brittleness that this might introduce.

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  • Mean of Sampleset and powered Sampleset

    - by Milla Well
    I am working on an ICA implementation wich is based on the assumption, that all source signals are independent. So I checked on the basic concepts of Dependence vs. Correlation and tried to show this example on sample data from numpy import * from numpy.random import * k = 1000 s = 10000 mn = 0 mnPow = 0 for i in arange(1,k): a = randn(s) a = a-mean(a) mn = mn + mean(a) mnPow = mnPow + mean(a**3) print "Mean X: ", mn/k print "Mean X^3: ", mnPow/k But I couldn't produce the last step of this example E(X^3) = 0: >> Mean X: -1.11174580826e-18 >> Mean X^3: -0.00125229267144 First value I would consider to be zero, but second value is too large, isn't it? Since I subtract the mean of a, I expected the mean of a^3 to be zero as well. Does the problem lie in the random number generator, the precision of the numerical values in my misunderstanding of the concepts of mean and expected value?

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  • Having a problem with reading a file using NSString initWithContents OfFile

    - by srikanth rongali
    In this program when I debug, it is showing the nil for fileNameString. I could not understand what is the problem. Please help me ? @implementation fromFileRead1 NSString *fileNameString; -(id)init { if( (self = [super init]) ) { fileNameString = [[NSString alloc] initWithContentsOfFile: @"enemyDetails.rtf" encoding:NSUTF8StringEncoding error:nil]; NSArray *lines = [fileNameString componentsSeparatedByString:@"\n"]; for (id *line in lines) { NSLog(@"Line1%@", line ); } } return self; } @end Thank You.

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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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  • 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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  • objective-c releasing uninitialized class members in dealloc method

    - by Dude Man
    Regarding over-releasing. Say I have a instance variable defined in Test.h NSString *mystring; In my implementation Test.m I do not initialize the variable mystring anywhere. But I release it in dealloc: -(void)dealloc { [mystring release]; } Is this now over-released? I've been doing the following in dealloc to avoid any issues, however, is this really necessary? -(void)dealloc { if (mystring) [mystring release]; } It seems that [nil release] shouldn't do anything, can someone verify this with class members?

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  • Socket left in TIME_WAIT after file transfer via netcat

    - by com
    Using Copying by NetCat I am trying to copy files throught network by NetCat. From console it work pretty well. First I run listening netcat on the destination machine and after I run sending on source machine. The problem is it's doen't work from script from the source machine: ssh -f user@$desthost 'nc -l 1234 | tar xvf - /dev/null &' #listening on destination host tar cv /tmp/file | nc $desthost 1234 #sending to destination host I saw that after running port 1234 is still was open and status of the socket was TIME_WAIT. If you know what's the problem, please, help me out. And by the way, after copying how can I validate that the content is identical? Thanks! Addendum: I found one very strange thing, the same implementation with screen on destination work works, but not stable, sometimes it doesn't copy a file. ssh user@$desthost screen -dm -S test 'nc -l 1234 | tar xvf - ' #listening on destination host Maybe there is an issue with timeout?

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  • FindBugs and CheckForNull on classes vs. interfaces

    - by ndn
    Is there any way to let FindBugs check and warn me if a CheckForNull annotation is present on the implementation of a method in a class, but not on the declaration of the method in the interface? import javax.annotation.CheckForNull; interface Foo { public String getBar(); } class FooImpl implements Foo { @CheckForNull @Override public String getBar() { return null; } } public class FindBugsDemo { public static void main(String[] args) { Foo foo = new FooImpl(); System.out.println(foo.getBar().length()); } } I just discovered a bug in my application due to a missing null check that was not spotted by FindBugs because CheckForNull was only present on FooImpl, but not on Foo, and I don't want to spot all other locations of this problem manually.

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  • iPhone app - Terminating DUE TO UNCAUGHT EXCEPTION

    - by Kenneth
    Hi Guys, im trying to switch views between view controllers but it crashed. so basically im switching from mainScreen to test i get an error in the Debugger 0x01d6a000 <+0000 push %ebp 0x01d6a001 <+0001 mov %esp,%ebp 0x01d6a003 <+0003 int3 0x01d6a004 <+0004 leave (HIGHLIGHTED) 0x01d6a005 <+0005 ret 0x01d6a006 <+0006 nopw %cs:0x0(%eax,%eax,1) mainscreen.h import @interface MainScreen : UIViewController { } -(IBAction)btnFirstPage:(id)sender; @end mainscreen.m import "MainScreen.h" import "test.h" @implementation MainScreen -(IBAction)btnFirstPage:(id)sender{ test1 = [[test1 alloc] initWithNibName:@"test" (test may not respond to -alloc) bundle:nil]; [self.view addSubview:test1.view]; .................etc test.h import @interface test : UIViewController { } @end test.m etc (did not edit)

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  • Using DAO's or static methods in Domain Object with nHibernate

    - by mickyjtwin
    I am using nHibernate for the first time, and after alot of reading/researching, plus looking at other projects done with nHibernate, have seen a couple of implementation practices. I am looking for opinions about which would be best to use and why. Essentially the two methods are as follows: Using Data Access Objects and a DAO Factory. Example usage: INotificationListDAO nListDAO = NHDaoFactory.GetNotificationListDAO(); NotificationList list = nListDAO.GetByListID(""); Use Static methods in the Domain Object. Example usage: NotificationList list = NotificationList.GetByListID(""); NHHelper.Session.Get(id); NHHelper.Session basically calls the NHibernateSessionManager.Instace.GetSessionFrom(""). While both look similar, it is more to do with best practice. From what I understand, the first option is more so if you are developing enterprise level applications, where my requirements are more for mid-range websites.

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  • Interface -> Entity Mapping

    - by KiD0M4N
    Hi guys, Suppose I have a few definitions like so: public interface ICategory { int ID { get; set; } string Name { get; set; } ICategory Parent { get; set; } } public class Category : ICategory { public virtual int ID { get; set; } public virtual string Name { get; set; } public virtual ICategory Parent { get; set; } } How do I map such a scenario in NHibernate? I am trying to separate the implementation of the DAL. I am learning NHibernate. Regards, Karan

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  • Visual Studio 2008, MSBuild: "replacement" projects

    - by liori
    Hello, My solution has a library project which needs a special environment to be built (lots of external libraries and tools)... but it is not vital to our application. We'd like to avoid installing these tools when not necessary (most of our developers work on other parts of code). We have created another project which has the same API, but has an empty implementation and is compilable without those external tools. I'd like to be able to easily switch between those projects and still get all the references in other projects correct. I don't know VS/MSBuild very well, but willing to learn whatever is necessary. Is it possible? I am looking for ideas... We're using Subversion, and solutions involving some hacks inside VCS are also welcome.

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  • What could possibly cause this error when declaring an object inside a class?

    - by M4design
    I'm battling with this assignment :) I've got two classes: Ocean and Grid. When I declare an object of the Grid inside the Ocean: unsigned int sharkCount; Grid grid; The compiler/complainer says: error C2146: syntax error : missing ';' before identifier 'grid' Can you possibly predict what produces this error with the limited info I provided? It seems that as if the Ocean doesn't like the Grid class. Could this be because of the poor implementation of the grid class. BTW the Grid has a default constructor. Yet the error happens in compiling time!. EDIT: They're each in separate header file, and I've included the Grid.h in the Ocean.h.

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  • Generate "Finder.h" for a SIMBL plugin

    - by user1204395
    I'm trying to create a SIMBL plugin for Finder to add icon overlay over some files. I have this code: @implementation NSObject (FAIconOverlay) - (void)FAIconOverlay_TIconAndTextCell_drawIconWithFrame:(struct CGRect)arg1 { [self FAIconOverlay_TIconAndTextCell_drawIconWithFrame:arg1]; if (![self respondsToSelector:@selector(node)]) { return; } NSLog(@"%@", [[[NSClassFromString(@"FINode") nodeWithFENode:[(TNodeIconAndNameCell *)self node]] fullPath] lastPathComponent]); // Draw the icon overlay } - (void)FAIconOverlay_TDesktopIcon_drawIconInContext:(struct CGContext *)arg1 { [self FAIconOverlay_TDesktopIcon_drawIconInContext:arg1]; } @end I can draw the icon overlay but, when I try to get the path of the file I get a "Use of undeclared identifier TNodeIconAndNameCell". Looking this link < How to Write OS X Finder plugin I see that is neccessary to generate a Finder.h file... My question is: How to generate this file?? I tried running "class-dump -H Finder.app" but I get too more compiling errors Thank you very much!

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  • Auto pointer for unsigned char array?

    - by Gianluca
    I'd need a class like std::auto_ptr for an array of unsigned char*, allocated with new[]. But auto_ptr only calls delete and not delete[], so i can't use it. I also need to have a function which creates and returns the array. I came out with my own implementation within a class ArrayDeleter, which i use like in this example: #include <Utils/ArrayDeleter.hxx> typedef Utils::ArrayDeleter<unsigned char> Bytes; void f() { // Create array with new unsigned char* xBytes = new unsigned char[10]; // pass array to constructor of ArrayDeleter and // wrap it into auto_ptr return std::auto_ptr<Bytes>(new Bytes(xBytes)); } ... // usage of return value { auto_ptr<Bytes> xBytes(f()); }// unsigned char* is destroyed with delete[] in destructor of ArrayDeleter Is there a more elegant way to solve this? (Even using another "popular" library)

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  • Delphi: OnTimer event of my own Timer never happens

    - by Mikhail
    I need a Timer in a 'no form' Delphi unit, so I do this: unit ... interface type TMyTimer = Class(TTimer) public procedure OnMyTimer(Sender: TObject); end; var MyTimer: TMyTimer; implementation procedure TMyTimer.OnMyTimer(Sender: TObject); begin ... end; initialization MyTimer := TMyTimer.Create(nil); with MyTimer do begin Interval := 1000; Enabled := True; OnTimer := OnMyTimer; end; finalization FreeAndNil(MouseTimer); The problem is that the OnMyTimer procedure is never run. I'll truly appreciate any ideas as to why :-)

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  • C5 Generics Collection IntervalHeap<T> -- getting an IPriorityQueueHandle from a T for Replace or De

    - by Jared Updike
    I'm using the Generics Collection library C5 (server down :-( ) and I have an IntervalHeap(T) and I need to Delete or Replace a T that is not the Max or Min. How do I get an IPriorityQueueHandle from my T? The C5 library source code shows that IPriorityQueueHandle(T) has no methods or properties to implement and the compiler thinks my implementation of IPriorityQueueHandle(T) for my T is acceptable. I try to use a T like this: q.Replace(t, t); and the C5 library throws an InvalidCastException because it cannot convert my T to a (Handle).

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  • Can I serialize a BitArray to XML?

    - by SimonNet
    Hello I have a business class which I need to serialize to xml. It has a BitArray property. I have decorated it with [XmlAttribute] but the serialization is failing with To be XML serializable, types which inherit from ICollection must have an implementation of Add(System.Boolean) at all levels of their inheritance hierarchy. System.Collections.BitArray does not implement Add(System.Boolean). I am not sure whether its possible to serialize to xml? If not what would be an efficient means of serializing the BitArray Thanks for looking

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  • In a virtual machine monitor such as VMware's ESXi Server, how are shadow page tables implemented?

    - by ali01
    My understanding is that VMMs such as VMware's ESXi Server maintain shadow page tables to map virtual page addresses of guest operating systems directly to machine (hardware) addresses. I've been told that shadow page tables are then used directly by the processor's paging hardware to allow memory access in the VM to execute without translation overhead. I would like to understand a bit more about how the shadow page table mechanism works in a VMM. Is my high level understanding above correct? What kind of data structures are used in the implementation of shadow page tables? What is the flow of control from the guest operating system all the way to the hardware? How are memory access translations made for a guest operating system before its shadow page table is populated? How is page sharing supported? Short of straight up reading the source code of an open source VMM, what resources can I look into to learn more about hardware virtualization?

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  • Java Enum Newbie Question

    - by ikurtz
    i have a situation where i need the Checker enum below used in multiple classes: package Sartre.Connect4; public enum Checker { EMPTY, RED, YELLOW } so i put the Checker in a Checker.java file and then from the classes that need it i simply do the following: example: public Cell(){ currentCell = Checker.EMPTY; } example: public Cell(Checker checker){ currentCell = checker; } and the code compiles fine and runs fine also. so what is my question? well being new to Java i am just wondering if the way i use Checker without encapsulating it in a class is a sound implementation? it may be because of The enum declaration defines a class (called an enum type). as noted in Java docs enum tutorial page. thank you for your insight into this matter.

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  • How can you implement a jQuery feature without having IE prompt users with an Active X warning?

    - by Bijan
    Essentially, I want to implement a jQuery feature on a site that I'm building, but I don't want Internet Explorer users to have to click "Allow Blocked Content". The feature works fine with Safari, Chrome, and Firefox. It's only IE that prompts the users with the Active X warning. I'm using the following jQuery cycle plugin: http://malsup.com/jquery/cycle/ I thought that I might simply have to live with the fact that users have to click on the Active X message when they use the site, but Zendesk (www.zendesk.com) is using the same implementation and that site doesn't prompt me with the warning. Any ideas as to what I'm doing wrong would be appreciated.

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  • Java - JPA - Generators - @SequenceGenerator

    - by Yatendra Goel
    I am learning JPA and have confusion in the @SequenceGenerator annotation. Upto my understanding, it automatically assigns a value to numeric identity fields/properties of an entity. Q1. Does this sequence generator make use of the database's increasing numeric value generating capability or generates the number on his own? Q2. If JPA uses database auto increement feauture, then will it work with datastores that don't have auto increement feature? Q3. If JPA generate numeric value on his own, then how the JPA implementation knows which value to generate next? Does it consult with the database first to see what value was stored last so as to generate the value (last + 1). ====================================================================================== Q4. Please also throw some light on sequenceName and allocationSize properties of @SequenceGenerator annotation.

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  • MVP pattern. Presenter requires new view instance. Best practice

    - by Andrew Florko
    I try to apply MVP pattern for win.forms application. I have 2 forms: main & child. Main has a button and when you click it - child form should appear. There are 2 views interfaces that forms implement IMainView { event OnClick; ... } IChildView { ... } There are two presenters MainPresenter(IMainView) & ChildPresenter(IChildView) MainPresenter listens to OnClick event and then should create IChildView implementation. MainPresenter { ... MainClicked() { // it's required to create IChildView instance here } } How would you implement such creation typically? Shall IMainView has factory method for IChildView or may be it should be separate Views factory. What would you advise? Or maybe there is some misunderstanding of MVP here? Thank you in advance!

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  • Process.WaitForExit not triggering with __debugbreak

    - by Cypher2100
    I'm trying to write a program to test student code against a good implementation. I have a C++ console app that will run one test at a time determined by the command line args and a C# .net forms app that calls the c++ app once for each test. The goal is to be able to detect not just pass/fail for each test, but also "infinite" (5secs) loop and exceptions (their code dying for whatever reason). The problem is that not all errors kill the C++ app. If they corrupt the heap the system calls __debugbreak which pops up a window saying Debug Error! HEAP CORRUPTION DETECTED... My C# app is using Process.WaitForExit(5000) to wait, but this error doesn't count as an exit, so I see a timeout. So my question is, how can I either get the C# app to detect that this is an error OR how can I get the C++ app to die when this error occurs rather than giving a dialog box and asking if I want to debug?

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