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• How to include the login form on the Home index page in MVC

  - by Bernard Larouche

  Hi guys I really need your help for this. I am relatively new to programming and I need help to something that could be easy for a experienced programmer. I would like to get the login form that we get for free in an MVC application on the left sidebar of my Home index page instead of the usual Account/Login page. I am facing some problems. First I need a product object to be displayed on my Home Index page as well. What I did is that I added a product object to the LogOnModel that they provide in the AccountModels class and I created a UserControl (partial view) copying the content of the LogOn.aspx view. Now my Home index.aspx as well as my partial view inherits the LogOnModel class. I can see the Login form on my Home Index page as well as my product object BUT the login Form is never empty. The last username and password always appear there. I know I must have forgotten something or have done something wrong or the way did it is completely wrong !! Please could you give me some advice Thks <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<CoderForTradersSite.Models.LogOnModel>" %> <h4>Login Form</h4> <p> Please enter your username and password. <%= Html.ActionLink("Register", "Register") %> if you don't have an account. </p> <% using (Html.BeginForm()) { %> <%= Html.ValidationSummary(true, "Login was unsuccessful. Please correct the errors and try again.") %> <div> <fieldset> <legend>Account Information</legend> <div class="editor-label"> <%= Html.LabelFor(m => m.UserName) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(m => m.UserName) %> <%= Html.ValidationMessageFor(m => m.UserName) %> </div> <div class="editor-label"> <%= Html.LabelFor(m => m.Password) %> </div> <div class="editor-field"> <%= Html.PasswordFor(m => m.Password) %> <%= Html.ValidationMessageFor(m => m.Password) %> </div> <div class="editor-label"> <%= Html.CheckBoxFor(m => m.RememberMe) %> <%= Html.LabelFor(m => m.RememberMe) %> </div> <p> <input type="submit" value="Log On" /> </p> </fieldset> </div> <% } %>

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• Unnecessary Java context switches

  - by Paul Morrison

  I have a network of Java Threads (Flow-Based Programming) communicating via fixed-capacity channels - running under WindowsXP. What we expected, based on our experience with "green" threads (non-preemptive), would be that threads would switch context less often (thus reducing CPU time) if the channels were made bigger. However, we found that increasing channel size does not make any difference to the run time. What seems to be happening is that Java decides to switch threads even though channels aren't full or empty (i.e. even though a thread doesn't have to suspend), which costs CPU time for no apparent advantage. Also changing Thread priorities doesn't make any observable difference. My question is whether there is some way of persuading Java not to make unnecessary context switches, but hold off switching until it is really necessary to switch threads - is there some way of changing Java's dispatching logic? Or is it reacting to something I didn't pay attention to?! Or are there other asynchronism mechanisms, e.g. Thread factories, Runnable(s), maybe even daemons (!). The answer appears to be non-obvious, as so far none of my correspondents has come up with an answer (including most recently two CS profs). Or maybe I'm missing something that's so obvious that people can't imagine my not knowing it... I've added the send and receive code here - not very elegant, but it seems to work...;-) In case you are wondering, I thought the goLock logic in 'send' might be causing the problem, but removing it temporarily didn't make any difference. I have added the code for send and receive... public synchronized Packet receive() { if (isDrained()) { return null; } while (isEmpty()) { try { wait(); } catch (InterruptedException e) { close(); return null; } if (isDrained()) { return null; } } if (isDrained()) { return null; } if (isFull()) { notifyAll(); // notify other components waiting to send } Packet packet = array[receivePtr]; array[receivePtr] = null; receivePtr = (receivePtr + 1) % array.length; //notifyAll(); // only needed if it was full usedSlots--; packet.setOwner(receiver); if (null == packet.getContent()) { traceFuncs("Received null packet"); } else { traceFuncs("Received: " + packet.toString()); } return packet; } synchronized boolean send(final Packet packet, final OutputPort op) { sender = op.sender; if (isClosed()) { return false; } while (isFull()) { try { wait(); } catch (InterruptedException e) { indicateOneSenderClosed(); return false; } sender = op.sender; } if (isClosed()) { return false; } try { receiver.goLock.lockInterruptibly(); } catch (InterruptedException ex) { return false; } try { packet.clearOwner(); array[sendPtr] = packet; sendPtr = (sendPtr + 1) % array.length; usedSlots++; // move this to here if (receiver.getStatus() == StatusValues.DORMANT || receiver.getStatus() == StatusValues.NOT_STARTED) { receiver.activate(); // start or wake up if necessary } else { notifyAll(); // notify receiver // other components waiting to send to this connection may also get // notified, // but this is handled by while statement } sender = null; Component.network.active = true; } finally { receiver.goLock.unlock(); } return true; }

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• C - circular character buffer w/ pthreads

  - by Matt

  I have a homework assignment where I have to implement a circular buffer and add and remove chars with separate threads: #include <pthread.h> #include <stdio.h> #define QSIZE 10 pthread_cond_t full,/* count == QSIZE */ empty,/* count == 0 */ ready; pthread_mutex_t m, n; /* implements critical section */ unsigned int iBuf, /* tail of circular queue */ oBuf; /* head of circular queue */ int count; /* count characters */ char buf [QSIZE]; /* the circular queue */ void Put(char s[]) {/* add "ch"; wait if full */ pthread_mutex_lock(&m); int size = sizeof(s)/sizeof(char); printf("size: %d", size); int i; for(i = 0; i < size; i++) { while (count >= QSIZE) pthread_cond_wait(&full, &m);/* is there empty slot? */ buf[iBuf] = s[i]; /* store the character */ iBuf = (iBuf+1) % QSIZE; /* increment mod QSIZE */ count++; if (count == 1) pthread_cond_signal(&empty);/* new character available */ } pthread_mutex_unlock(&m); } char Get() {/* remove "ch" from queue; wait if empty */ char ch; pthread_mutex_lock(&m); while (count <= 0) pthread_cond_wait(&empty, &m);/* is a character present? */ ch = buf[oBuf]; /* retrieve from the head of the queue */ oBuf = (oBuf+1) % QSIZE; count--; if (count == QSIZE-1) pthread_cond_signal(&full);/* signal existence of a slot */ pthread_mutex_unlock(&m); return ch; } void * p1(void *arg) { int i; for (i = 0; i < 5; i++) { Put("hella"); } } void * p2(void *arg) { int i; for (i = 0; i < 5; i++) { Put("goodby"); } } int main() { pthread_t t1, t2; void *r1, *r2; oBuf = 0; iBuf = 0; count=0; /* all slots are empty */ pthread_cond_init(&full, NULL); pthread_cond_init(&empty, NULL); pthread_mutex_init(&m, NULL); pthread_create(&t1, NULL, p1, &r1); pthread_create(&t2, NULL, p2, &r2); printf("Main"); char c; int i = 0; while (i < 55) { c = Get(); printf("%c",c); i++; } pthread_join(t1, &r1); pthread_join(t2, &r2); return 0; } I shouldn't have to change the logic much at all, the requirements are pretty specific. I think my problem lies in the Put() method. I think the first thread is going in and blocking the critical section and causing a deadlock. I was thinking I should make a scheduling attribute? Of course I could be wrong. I am pretty new to pthreads and concurrent programming, so I could really use some help spotting my error.

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• WPF BackgroundWorker Execution

  - by Sanju

  Hi All, I've been programming C# for a while now (I'm a Computer Science major), and have never had to implement threading. I am currently building an application for a client that requires threading for a series of operations. Due to the nature of the client/provider agreement, I cannot release the source I am working with. The code that I have posted is in a general form. Pretty much the basic idea of what I am implementing, excluding the content specific source. The first Snippet demonstrates my basic structure, The Progress class is a custom progress window that is displayed as a dialog to prevent user UI interaction. I am currently using the code to complete database calls based on a collection of objects in another area of the application code. For example, I have a collection of "Objects" of one of my custom classes, that I perform these database calls on or on behalf of. My current set up works just fine when I call the "GeneralizedFunction" one and only one time. What I need to do is call this function once for every object in the collection. I was attempting to use a foreach loop to iterate through the collection, then I tried a for loop. For both loops, the result was the same. The Async operation performs exactly as desired for the first item in the collection. This, however, is the only one it works for. For each subsequent item, the progress box (my custom window) displays and immediately closes. In terms of the database calls, the calls for the first item in the collection are the only ones that successfully complete. All others aren't attempted. I've tried everything that I know and don't know to do, but I just cannot seem to get it to work. How can I get this to work for my entire collection? Any and all help is very greatly appreciated. Progress progress; BackgroundWorker worker; // Cancel the current process private void CancelProcess(object sender, EventArgs e) { worker.CancelAsync(); } // The main process ... "Generalized" private void GeneralizedFunction() { progress = new Progress(); progress.Cancel += CancelProcess; progress.Owner = this; Dispatcher pDispatcher = progress.Dispatcher; worker = new BackgroundWorker(); worker.WorkerSupportsCancellation = true; object[] workArgs = { arg1, arg2, arg3}; worker.DoWork += delegate(object s, DoWorkEventArgs args) { /* All main logic here */ foreach(Class ClassObject in ClassObjectCollection) { //Some more logic here UpdateProgressDelegate update = new UpdateProgressDelegate(updateProgress); pDispatcher.BeginInvoke(update, arg1,arg2,arg3); Thread.Sleep(1000); } }; worker.RunWorkerCompleted += delegate(object s, RunWorkerCompletedEventArgs args) { progress.Close(); }; worker.RunWorkerAsync(workArgs); progress.ShowDialog(); } public delegate void UpdateProgressDelegate(arg1,arg2,arg3); private void updateProgress(arg1,arg2,arg3) { //Update progress }

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• evaluating cost/benefits of using extension methods in C# => 3.0

  - by BillW

  Hi, In what circumstances (usage scenarios) would you choose to write an extension rather than sub-classing an object ? < full disclosure : I am not an MS employee; I do not know Mitsu Furota personally; I do know the author of the open-source Componax library mentioned here, but I have no business dealings with him whatsoever; I am not creating, or planning to create any commercial product using extensions : in sum : this post is from pure intellectal curiousity related to my trying to (continually) become aware of "best practices" I find the idea of extension methods "cool," and obviously you can do "far-out" things with them as in the many examples you can in Mitsu Furota's (MS) blog postslink text. A personal friend wrote the open-source Componax librarylink text, and there's some remarkable facilities in there; but he is in complete command of his small company with total control over code guidelines, and every line of code "passes through his hands." While this is speculation on my part : I think/guess other issues might come into play in a medium-to-large software team situation re use of Extensions. Looking at MS's guidelines at link text, you find : In general, you will probably be calling extension methods far more often than implementing your own. ... In general, we recommend that you implement extension methods sparingly and only when you have to. Whenever possible, client code that must extend an existing type should do so by creating a new type derived from the existing type. For more information, see Inheritance (C# Programming Guide). ... When the compiler encounters a method invocation, it first looks for a match in the type's instance methods. If no match is found, it will search for any extension methods that are defined for the type, and bind to the first extension method that it finds. And at Ms's link text : Extension methods present no specific security vulnerabilities. They can never be used to impersonate existing methods on a type, because all name collisions are resolved in favor of the instance or static method defined by the type itself. Extension methods cannot access any private data in the extended class. Factors that seem obvious to me would include : I assume you would not write an extension unless you expected it be used very generally and very frequently. On the other hand : couldn't you say the same thing about sub-classing ? Knowing we can compile them into a seperate dll, and add the compiled dll, and reference it, and then use the extensions : is "cool," but does that "balance out" the cost inherent in the compiler first having to check to see if instance methods are defined as described above. Or the cost, in case of a "name clash," of using the Static invocation methods to make sure your extension is invoked rather than the instance definition ? How frequent use of Extensions would affect run-time performance or memory use : I have no idea. So, I'd appreciate your thoughts, or knowing about how/when you do, or don't do, use Extensions, compared to sub-classing. thanks, Bill

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• How to design a C / C++ library to be usable in many client languages?

  - by Brian Schimmel

  I'm planning to code a library that should be usable by a large number of people in on a wide spectrum of platforms. What do I have to consider to design it right? To make this questions more specific, there are four "subquestions" at the end. Choice of language Considering all the known requirements and details, I concluded that a library written in C or C++ was the way to go. I think the primary usage of my library will be in programs written in C, C++ and Java SE, but I can also think of reasons to use it from Java ME, PHP, .NET, Objective C, Python, Ruby, bash scrips, etc... Maybe I cannot target all of them, but if it's possible, I'll do it. Requirements It would be to much to describe the full purpose of my library here, but there are some aspects that might be important to this question: The library itself will start out small, but definitely will grow to enormous complexity, so it is not an option to maintain several versions in parallel. Most of the complexity will be hidden inside the library, though The library will construct an object graph that is used heavily inside. Some clients of the library will only be interested in specific attributes of specific objects, while other clients must traverse the object graph in some way Clients may change the objects, and the library must be notified thereof The library may change the objects, and the client must be notified thereof, if it already has a handle to that object The library must be multi-threaded, because it will maintain network connections to several other hosts While some requests to the library may be handled synchronously, many of them will take too long and must be processed in the background, and notify the client on success (or failure) Of course, answers are welcome no matter if they address my specific requirements, or if they answer the question in a general way that matters to a wider audience! My assumptions, so far So here are some of my assumptions and conclusions, which I gathered in the past months: Internally I can use whatever I want, e.g. C++ with operator overloading, multiple inheritance, template meta programming... as long as there is a portable compiler which handles it (think of gcc / g++) But my interface has to be a clean C interface that does not involve name mangling Also, I think my interface should only consist of functions, with basic/primitive data types (and maybe pointers) passed as parameters and return values If I use pointers, I think I should only use them to pass them back to the library, not to operate directly on the referenced memory For usage in a C++ application, I might also offer an object oriented interface (Which is also prone to name mangling, so the App must either use the same compiler, or include the library in source form) Is this also true for usage in C# ? For usage in Java SE / Java EE, the Java native interface (JNI) applies. I have some basic knowledge about it, but I should definitely double check it. Not all client languages handle multithreading well, so there should be a single thread talking to the client For usage on Java ME, there is no such thing as JNI, but I might go with Nested VM For usage in Bash scripts, there must be an executable with a command line interface For the other client languages, I have no idea For most client languages, it would be nice to have kind of an adapter interface written in that language. I think there are tools to automatically generate this for Java and some others For object oriented languages, it might be possible to create an object oriented adapter which hides the fact that the interface to the library is function based - but I don't know if its worth the effort Possible subquestions is this possible with manageable effort, or is it just too much portability? are there any good books / websites about this kind of design criteria? are any of my assumptions wrong? which open source libraries are worth studying to learn from their design / interface / souce? meta: This question is rather long, do you see any way to split it into several smaller ones? (If you reply to this, do it as a comment, not as an answer)

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• How can I tell the size of my app during development?

  - by Newbyman

  My programming decissions are directly related to how much room I have left, or worse perhaps how much I need to shave off in order to get up the 10mb limit. I have read that Apple has quietly increased the 3G & Edge download limit from 10mb up to 20mb in preparation for the iPad in April. Either way, my real question is how can I gauge a rough estimate of how large my app will end while I'm still in the development phase? Is the file size of my development folder roughly 1 to 1 ratio? Is the compressed file size of my development a better approximation? My .xcodeproj file is only a couple hundred kB, but the size of my folder is 11.8 MB. I have a .sqlite database, less than 20 small png images and a Settings.Bundle. The rest are unknown Xcode files related to build, build for iphoneOS, simulator etc.... My source code is rather large with around 1000 lines in most of the major controllers, all in all around 48 .h&.m files. But my classes folder inside my development folder is less than 800kb. Digging around inside my Build file, there is lots of iphone simulator files and debugging files which I don't think will contribute to the final product. The Application file states that it is around 2.3 MB. However, this is such a large difference from the 11.8 MB, I have to wonder if this is just another piece of the equation. I have the app on the my device, I'm in the testing phase. Therefore, I though that I would try to see how large the working version was on the device by checking in iTunes, however my development app is visible on the right-hand the application's iphone screen, but no information about the app most importantly its size. I also checked in Organizer, I used the lower portion of the screen-(Applications), found my application and selected the drop down arrow which gave my "Application Data" and a download arrow button to the right to save a file on my desktop, named with the unique AppleID. Inside the folder it had three folders-(documents, library, tmp) the documents had a copy of my .sqlite database, the library a few more files but not anything obvious or of size, and the tmp was empty. All in all the entire folder was only 164kb-which tells me that this is not the right place to find the size either. I understand that the size is considered to be the size of my binary plus all the additional files and images that I have add. Does anyone have a effective way of guaging how large the binary is or the relating the development folder size to what the final App Store application size will end up. I know that questions have been posted with similar aspects, but I could not find any answered post that really described...what files, or how to determine size specifically. I know that this question looks like a book, but I just wanted to be specific in conveying exactly what I'm looking for and the attempts thus far. *Note all files are unzipped and still in regular working Xcode order of a single app with no brought-in builds or referenced projects. I'm sure that this is straight forward, I just don't know where to look?

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• segmented controls mangled during initial transition animation

  - by dLux

  greetings and salutations folks, i'm relatively new to objective c & iphone programming, so bare with me if i've overlooked something obvious.. i created a simple app to play with the different transition animations, setting up a couple segmented controls and a slider.. (Flip/Curl), (left/right) | (up/down), (EaseInOut/EaseIn/EaseOut/Linear) i created a view controller class, and the super view controller switches between 2 instances of the sub class. as you can see from the following image, the first time switching to the 2nd instance, while the animation is occurring the segmented controls are mangled; i'd guess they haven't had enuff time to draw themselves completely.. http://img689.imageshack.us/img689/2320/mangledbuttonsduringtra.png they're fine once the animation is done, and any subsequent times.. if i specify cache:NO in the setAnimationTransition it helps, but there still seems to be some sort of progressive reveal for the text in the segmented controls; they still don't seem to be pre-rendered or initialized properly.. (and surely there's a way to do this while caching the view being transitioned to, since in this case the view isn't changing and should be cacheable.) i'm building my code based on a couple tutorials from a book, so i updated the didReceiveMemoryWarning to set the instanced view controllers to nil; when i invoke a memory warning in the simulator, i assume it's purging the other view, and it acts like a first transition after loading, the view being transitioned to appears just like the image above.. i guess it can't hurt to include the code (sorry if it's considered spamming), this is basically half of it, with a similar chunk following this in an else statement, for the case of the 2nd side being present, switching back to the 1st..: - (IBAction)switchViews:(id)sender { [UIView beginAnimations:@"Transition Animation" context:nil]; if (self.sideBViewController.view.superview == nil) // sideA is active, sideB is coming { if (self.sideBViewController == nil) { SideAViewController *sBController = [[SideAViewController alloc] initWithNibName:@"SideAViewController" bundle:nil]; self.sideBViewController = sBController; [sBController release]; } [UIView setAnimationDuration:sideAViewController.transitionDurationSlider.value]; if ([sideAViewController.transitionAnimation selectedSegmentIndex] == 0) { // flip: 0 == left, 1 == right if ([sideAViewController.flipDirection selectedSegmentIndex] == 0) [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.view cache:YES]; else [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.view cache:YES]; } else { // curl: 0 == up, 1 == down if ([sideAViewController.curlDirection selectedSegmentIndex] == 0) [UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:self.view cache:YES]; else [UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:self.view cache:YES]; } if ([sideAViewController.animationCurve selectedSegmentIndex] == 0) [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut]; else if ([sideAViewController.animationCurve selectedSegmentIndex] == 1) [UIView setAnimationCurve:UIViewAnimationCurveEaseIn]; else if ([sideAViewController.animationCurve selectedSegmentIndex] == 2) [UIView setAnimationCurve:UIViewAnimationCurveEaseOut]; else if ([sideAViewController.animationCurve selectedSegmentIndex] == 3) [UIView setAnimationCurve:UIViewAnimationCurveLinear]; [sideBViewController viewWillAppear:YES]; [sideAViewController viewWillDisappear:YES]; [sideAViewController.view removeFromSuperview]; [self.view insertSubview:sideBViewController.view atIndex:0]; [sideBViewController viewDidAppear:YES]; [sideAViewController viewDidDisappear:YES]; } any other tips or pointers about writing good clean code is also appreciated, i realize i still have a lot to learn.. thank u for ur time, -- d

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• Future of VB.NET? [closed]

  - by Alex Yeung

  Hi all, I worked with C# for years. Last year, I changed my job and the company use VB.NET. Of course, theoretically C# and VB.NET are very similar and I easily adapted. However, I have worked for VB.NET for 1 year. I cannot see any future of VB.NET. As a programming language, it is so foo. Here is a list of what C# can do but VB.NET cannot Case insensitive variables how to think a new variable name? If I have a property called FolderPath, i need to establish another private variable called _folderPath or m_folderPath. In C#, FolderPath and folderPath are two variables. Moreover, it gets compile error if variable name is same as a class name. For example Dim guid = Guid.NewGuid(). (What the...) Again, I need to think a new variable name. Adhoc scope In C#, we could use {...} to create a adhoc scope and all resource in {...} will not affect the code outside. However there is not such syntax in VB.NET. I could only use If True Then and End If to make a local scope which is so unclear. In-Method Region Sometime, it is unavoidable to have a long long method. VB.NET does not support in-method region. I always need to scroll down for 1000 lines. It wastes my time. No multi-line string definition In C#, we could var s = @"..." to define a multi-line string. In VB.NET there is no direct method to do that. The indirect way is use XML-literal string. Dim s = <![CDATA[...]]>.Value. However it is unclear. No block comment In C#, we have line comment // and block comment /* ... */. However in VB.NET we only have line comment which is a very big trouble for me. No statement end symbol Statements are separated by line break in VB.NET; while statements are separated by ; in C#. Underscore I think many people know underscore _ is continue statement symbol. I really disagree with that. I know MS VB.NET language team is going to remove the underscore syntax from VB.NET. However what can we do now? Although underscore is removed in the future, what's the advantage of that? I cannot see any advantage! With scope With scope is an evil scope. Although it allows shorter statement, it is hard to trace. Default Namesapce in project level It is a nightmare for me. The only advantage of VB.NET is property initialization. I think C# cannot do that (correct me if I am wrong.) Public Property ThisIsMyProperty As String = "MyValue" Remarks: I don't think optional method parameters is an advantage of OOP. By those disadvantages, I cannot see the future of VB.NET. Anyone sees the future of VB.NET?

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• Trouble in ActiveX multi-thread invoke javascript callback routine

  - by code0tt

  everyone. I'm get some trouble in ActiveX programming with ATL. I try to make a activex which can async-download files from http server to local folder and after download it will invoke javascript callback function. My solution: run a thread M to monitor download thread D, when D is finish the job, M is going to terminal themself and invoke IDispatch inferface to call javascript function. **************** THERE IS MY CODE: **************** /* javascript code */ funciton download() { var xfm = new ActiveXObject("XFileMngr.FileManager.1"); xfm.download( 'http://somedomain/somefile','localdev:\\folder\localfile',function(msg){alert(msg);}); } /* C++ code */ // main routine STDMETHODIMP CFileManager::download(BSTR url, BSTR local, VARIANT scriptCallback) { CString csURL(url); CString csLocal(local); CAsyncDownload download; download.Download(this, csURL, csLocal, scriptCallback); return S_OK; } // parts of CAsyncDownload.h typedef struct tagThreadData { CAsyncDownload* pThis; } THREAD_DATA, *LPTHREAD_DATA; class CAsyncDownload : public IBindStatusCallback { private: LPUNKNOWN pcaller; CString csRemoteFile; CString csLocalFile; CComPtr<IDispatch> spCallback; public: void onDone(HRESULT hr); HRESULT Download(LPUNKNOWN caller, CString& csRemote, CString& csLocal, VARIANT callback); static DWORD __stdcall ThreadProc(void* param); }; // parts of CAsyncDownload.cpp void CAsyncDownload::onDone(HRESULT hr) { if(spCallback) { TRACE(TEXT("invoke callback function\n")); CComVariant vParams[1]; vParams[0] = "callback is working!"; DISPPARAMS params = { vParams, NULL, 1, 0 }; HRESULT hr = spCallback->Invoke(0, IID_NULL, LOCALE_USER_DEFAULT, DISPATCH_METHOD, &params, NULL, NULL, NULL); if(FAILED(hr)) { CString csBuffer; csBuffer.Format(TEXT("invoke failed, result value: %d \n"),hr); TRACE(csBuffer); }else { TRACE(TEXT("invoke was successful\n")); } } } HRESULT CAsyncDownload::Download(LPUNKNOWN caller, CString& csRemote, CString& csLocal, VARIANT callback) { CoInitializeEx(NULL, COINIT_MULTITHREADED); csRemoteFile = csRemote; csLocalFile = csLocal; pcaller = caller; switch(callback.vt){ case VT_DISPATCH: case VT_VARIANT:{ spCallback = callback.pdispVal; } break; default:{ spCallback = NULL; } } LPTHREAD_DATA pData = new THREAD_DATA; pData->pThis = this; // create monitor thread M HANDLE hThread = CreateThread(NULL, 0, ThreadProc, (void*)(pData), 0, NULL); if(!hThread) { delete pData; return HRESULT_FROM_WIN32(GetLastError()); } WaitForSingleObject(hThread, INFINITE); CloseHandle(hThread); CoUninitialize(); return S_OK; } DWORD __stdcall CAsyncDownload::ThreadProc(void* param) { LPTHREAD_DATA pData = (LPTHREAD_DATA)param; // here, we will create http download thread D // when download job is finish, call onDone method; pData->pThis->onDone(S_OK); delete pData; return 0; } **************** CODE FINISH **************** OK, above is parts of my source code, if I call onDone method in sub-thread, I will get OLE ERROR(-2147418113 (8000FFFF) Catastrophic failure.). Did I miss something? please help me to figure it out.

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• What's wrong in this C program..? [closed]

  - by AGeek

  struct bucket { int nStrings; //No. of Strings in a Bucket. char strings[MAXSTRINGS][MAXWORDLENGTH]; // A bucket row can contain maximum 9 strings of max string length 10. };//buck[TOTBUCKETS]; void lexSorting(char array[][10], int lenArray, int symb) //symb - symbol, sorting based on character symbols. { int i, j; int bucketNo; int tBuckNStrings; bucket buck[TOTBUCKETS]; for(i=0; i<lenArray; i++) { bucketNo = array[i][symb] - 'a'; // Find Bucket No. in which the string is to be placed. tBuckNStrings = buck[bucketNo].nStrings; // temp variable for storing nStrings var in bucket structure. strcpy(buck[bucketNo].strings[tBuckNStrings],array[i]); // Store the string in its bucket. buck[bucketNo].nStrings = ++tBuckNStrings; //Increment the nStrings value of the bucket. } // lexSorting(array, lenArray, ++symb); printf("****** %d ******\n", symb); for(i=0; i<TOTBUCKETS; i++) { printf("%c = ", i+'a'); for(j=0; j<buck[i].nStrings; j++) printf("%s ",buck[i].strings[j]); printf("\n"); } } int main() { char array[][10] = {"able","aback","a","abet","acid","yawn","yard","yarn","year","yoke"}; int lenArray = 10; int i; printf("Strings: "); for(i=0; i<lenArray; i++) printf("%s ",array[i]); printf("\n"); lexSorting(array, lenArray, 0); } Well here is the complete code, that I am trying. since its been a long time since i have touched upon C programming, so somewhere i am making mistake in structure declaration. The problem goes here:- 1) I have declared a structure above and its object as array(buck[]). 2) Now when I declare this object array along with the structure, it works fine.. I have commented this thing right now. 3) But when I declare this object array inside the function.. because ultimately i have to declare inside function( as i need to build a recursive program, where objects will be created in very recursive call) then the program is throwing segmentation fault. Expected Output > [others@centos htdocs]$ ./a.out > Strings: able aback a abet acid yawn > yard yarn year yoke > ****** 0 ****** > a = able aback a abet acid > b = > c > . > . > y = yawn yard yarnyear yoke > z = Actual Output [others@centos htdocs]$ ./a.out Strings: able aback a abet acid yawn yard yarn year yoke Segmentation fault I have no idea, what difference I made in this. Kindly help. Thanks.

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• Write to file depending on minSdkVersion - android

  - by Simon Rosenqvist

  Hi, I have written a filewriter for my android application. It is to function on a Galaxy Tab, so my minSdkVersion has to be at least 4, so it will fill the screen. I originally started out with SdkVersion = 2 and at that point my filewriter worked perfectly. Changing the SdkVersion to 4 introduced the problem. My filewriter doesn't work anymore! The application runs fine, but a file doesn't get created. My .java file looks like this: public class HelloAndroid extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); TextView tv = new TextView(this); tv.setText("Hello, Android"); setContentView(R.layout.main); //definerer en knap kaldet button1 og sætter en listener på denne. Button button1 = (Button)findViewById(R.id.btnClickMe); button1.setOnClickListener(btnListener); //definerer en knap kaldet button2 og sætter en listener på denne. Button button2 = (Button)findViewById(R.id.btnClickMe2); button2.setOnClickListener(btnListener2); } //en variabel af typen 'long' deklæres og kaldes tid1. public long time1; private OnClickListener btnListener = new OnClickListener() { public void onClick(View v) { //Når der klikkes på button1 gemmes et tal i variablen tid1. time1 = System.currentTimeMillis(); } }; //en variabel af typen 'long' deklæres og kaldes tid2. public long time2; // en variabel af typen 'string' deklæres og kaldes tid: public String string1 = "time:"; private OnClickListener btnListener2 = new OnClickListener() { public void onClick(View v) { //Når der klikkes på button2 gemmes et tal i variablen tid2. time2 = System.currentTimeMillis(); // Herefter oprettes en fil kaldet "file.txt". try{ File file = new File(Environment.getExternalStorageDirectory(), "file.txt"); file.createNewFile(); BufferedWriter writer = new BufferedWriter(new FileWriter(file,true)); //string1 og tid2-tid1 skrives til filen. tid2-tid1 giver den tid der går fra der er trykket på den ene knap til den anden i millisekunder. writer.write(string1 + "\t" + (time2-time1)); writer.newLine(); writer.flush(); writer.close(); } catch (IOException e) { e.printStackTrace(); } } }; } And my manifest.xml looks like this: <?xml version="1.0" encoding="utf-8"?> <application android:icon="@drawable/icon" android:label="@string/app_name"> <activity android:name=".HelloAndroid" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> Why does my filewriter not work with minSdkVersion 2? Do i have to make a new filewriter? or what to do? Sorry for the messy code, i'm quite new to programming :)

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• [C#][XNA] Draw() 20,000 32 by 32 Textures or 1 Large Texture 20,000 Times

  - by Rudi

  The title may be confusing - sorry about that, it's a poor summary. Here's my dilemma. I'm programming in C# using the .NET Framework 4, and aiming to make a tile-based game with XNA. I have one large texture (256 pixels by 4096 pixels). Remember this is a tile-based game, so this texture is so massive only because it contains many tiles, which are each 32 pixels by 32 pixels. I think the experts will definitely know what a tile-based game is like. The orientation is orthogonal (like a chess board), not isometric. In the Game.Draw() method, I have two choices, one of which will be incredibly more efficient than the other. Choice/Method #1: Semi-Pseudocode: public void Draw() { // map tiles are drawn left-to-right, top-to-bottom for (int x = 0; x < mapWidth; x++) { for (int y = 0; y < mapHeight; y++) { SpriteBatch.Draw( MyLargeTexture, // One large 256 x 4096 texture new Rectangle(x, y, 32, 32), // Destination rectangle - ignore this, its ok new Rectangle(x, y, 32, 32), // Notice the source rectangle 'cuts out' 32 by 32 squares from the texture corresponding to the loop Color.White); // No tint - ignore this, its ok } } } Caption: So, effectively, the first method is referencing one large texture many many times, each time using a small rectangle of this large texture to draw the appropriate tile image. Choice/Method #2: Semi-Pseudocode: public void Draw() { // map tiles are drawn left-to-right, top-to-bottom for (int x = 0; x < mapWidth; x++) { for (int y = 0; y < mapHeight; y++) { Texture2D tileTexture = map.GetTileTexture(x, y); // Getting a small 32 by 32 texture (different each iteration of the loop) SpriteBatch.Draw( tileTexture, new Rectangle(x, y, 32, 32), // Destination rectangle - ignore this, its ok new Rectangle(0, 0, tileTexture.Width, tileTexture.Height), // Notice the source rectangle uses the entire texture, because the entire texture IS 32 by 32 Color.White); // No tint - ignore this, its ok } } } Caption: So, effectively, the second method is drawing many small textures many times. The Question: Which method and why? Personally, I would think it would be incredibly more efficient to use the first method. If you think about what that means for the tile array in a map (think of a large map with 2000 by 2000 tiles, let's say), each Tile object would only have to contain 2 integers, for the X and Y positions of the source rectangle in the one large texture - 8 bytes. If you use method #2, however, each Tile object in the tile array of the map would have to store a 32by32 Texture - an image - which has to allocate memory for the R G B A pixels 32 by 32 times - is that 4096 bytes per tile then? So, which method and why? First priority is speed, then memory-load, then efficiency or whatever you experts believe.

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• MySQL and INT auto_increment fields

  - by PHPguy

  Hello folks, I'm developing in LAMP (Linux+Apache+MySQL+PHP) since I remember myself. But one question was bugging me for years now. I hope you can help me to find an answer and point me into the right direction. Here is my challenge: Say, we are creating a community website, where we allow our users to register. The MySQL table where we store all users would look then like this: CREATE TABLE `users` ( `uid` int(2) unsigned NOT NULL auto_increment COMMENT 'User ID', `name` varchar(20) NOT NULL, `password` varchar(32) NOT NULL COMMENT 'Password is saved as a 32-bytes hash, never in plain text', `email` varchar(64) NOT NULL, `created` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of registration', `updated` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of profile update, e.g. change of email', PRIMARY KEY (`uid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; So, from this snippet you can see that we have a unique and automatically incrementing for every new user 'uid' field. As on every good and loyal community website we need to provide users with possibility to completely delete their profile if they want to cancel their participation in our community. Here comes my problem. Let's say we have 3 registered users: Alice (uid = 1), Bob (uid = 2) and Chris (uid = 3). Now Bob want to delete his profile and stop using our community. If we delete Bob's profile from the 'users' table then his missing 'uid' will create a gap which will be never filled again. In my opinion it's a huge waste of uid's. I see 3 possible solutions here: 1) Increase the capacity of the 'uid' field in our table from SMALLINT (int(2)) to, for example, BIGINT (int(8)) and ignore the fact that some of the uid's will be wasted. 2) introduce the new field 'is_deleted', which will be used to mark deleted profiles (but keep them in the table, instead of deleting them) to re-utilize their uid's for newly registered users. The table will look then like this: CREATE TABLE `users` ( `uid` int(2) unsigned NOT NULL auto_increment COMMENT 'User ID', `name` varchar(20) NOT NULL, `password` varchar(32) NOT NULL COMMENT 'Password is saved as a 32-bytes hash, never in plain text', `email` varchar(64) NOT NULL, `is_deleted` int(1) unsigned NOT NULL default '0' COMMENT 'If equal to "1" then the profile has been deleted and will be re-used for new registrations', `created` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of registration', `updated` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of profile update, e.g. change of email', PRIMARY KEY (`uid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; 3) Write a script to shift all following user records once a previous record has been deleted. E.g. in our case when Bob (uid = 2) decides to remove his profile, we would replace his record with the record of Chris (uid = 3), so that uid of Chris becomes qual to 2 and mark (is_deleted = '1') the old record of Chris as vacant for the new users. In this case we keep the chronological order of uid's according to the registration time, so that the older users have lower uid's. Please, advice me now which way is the right way to handle the gaps in the auto_increment fields. This is just one example with users, but such cases occur very often in my programming experience. Thanks in advance!

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• More localized, efficient Lowest Common Ancestor algorithm given multiple binary trees?

  - by mstksg

  I have multiple binary trees stored as an array. In each slot is either nil (or null; pick your language) or a fixed tuple storing two numbers: the indices of the two "children". No node will have only one child -- it's either none or two. Think of each slot as a binary node that only stores pointers to its children, and no inherent value. Take this system of binary trees: 0 1 / \ / \ 2 3 4 5 / \ / \ 6 7 8 9 / \ 10 11 The associated array would be: 0 1 2 3 4 5 6 7 8 9 10 11 [ [2,3] , [4,5] , [6,7] , nil , nil , [8,9] , nil , [10,11] , nil , nil , nil , nil ] I've already written simple functions to find direct parents of nodes (simply by searching from the front until there is a node that contains the child) Furthermore, let us say that at relevant times, both all trees are anywhere between a few to a few thousand levels deep. I'd like to find a function P(m,n) to find the lowest common ancestor of m and n -- to put more formally, the LCA is defined as the "lowest", or deepest node in which have m and n as descendants (children, or children of children, etc.). If there is none, a nil would be a valid return. Some examples, given our given tree: P( 6,11) # => 2 P( 3,10) # => 0 P( 8, 6) # => nil P( 2,11) # => 2 The main method I've been able to find is one that uses an Euler trace, which turns the given tree, with a node A to be the invisible parent of 0 and 1 with a depth of -1, into: A-0-2-6-2-7-10-7-11-7-2-0-3-0-A-1-4-1-5-8-5-9-5-1-A And from that, simply find the node between your given m and n that has the lowest number; For example, to find P(6,11), look for a 6 and an 11 on the trace. The number between them that is the lowest is 2, and that's your answer. If A is in between them, return nil. -- Calculating P(6,11) -- A-0-2-6-2-7-10-7-11-7-2-0-3-0-A-1-4-1-5-8-5-9-5-1-A ^ ^ ^ | | | m lowest n Unfortunately, I do believe that finding the Euler trace of a tree that can be several thousands of levels deep is a bit machine-taxing...and because my tree is constantly being changed throughout the course of the programming, every time I wanted to find the LCA, I'd have to re-calculate the Euler trace and hold it in memory every time. Is there a more memory efficient way, given the framework I'm using? One that maybe iterates upwards? One way I could think of would be the "count" the generation/depth of both nodes, and climb the lowest node until it matched the depth of the highest, and increment both until they find someone similar. But that'd involve climbing up from level, say, 3025, back to 0, twice, to count the generation, and using a terribly inefficient climbing-up algorithm in the first place, and then re-climbing back up. Are there any other better ways?

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• iphone web service access

  - by malleswar

  Hi, I have .net webservice methods login and summary. After getting the result from login, I need to show second view and need to call summary method. I am following this tutorial. http://icodeblog.com/2008/11/03/iphone-programming-tutorial-intro-to-soap-web-services/ I created two new classes loginaccess.h and loginaccess.m. @implementation LoginAccess @synthesize ResultString,webData, soapResults, xmlParser; -(NSString*)LoginCheck:(NSString*)userName:(NSString*)pwd { NSString *soapMessage = [NSString stringWithFormat: @"\n" "\n" "\n" "\n" "%@" "%@" "" "\n" "\n",userName,pwd ]; NSLog(soapMessage); NSURL *url = [NSURL URLWithString:@"http://www.XXXXXXXXX.com/service.asmx"]; NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:url]; NSString *msgLength = [NSString stringWithFormat:@"%d", [soapMessage length]]; [theRequest addValue: @"text/xml; charset=utf-8" forHTTPHeaderField:@"Content-Type"]; [theRequest addValue: @"http://XXXXXXXXm/Login" forHTTPHeaderField:@"SOAPAction"]; [theRequest addValue: msgLength forHTTPHeaderField:@"Content-Length"]; [theRequest setHTTPMethod:@"POST"]; [theRequest setHTTPBody: [soapMessage dataUsingEncoding:NSUTF8StringEncoding]]; NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self]; if( theConnection ) { webData = [[NSMutableData data] retain]; } else { NSLog(@"theConnection is NULL"); } //[nameInput resignFirstResponder]; return ResultString; } -(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { [webData setLength: 0]; } -(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { [webData appendData:data]; } -(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { NSLog(@"ERROR with theConenction"); [connection release]; [webData release]; } -(void)connectionDidFinishLoading:(NSURLConnection *)connection { NSLog(@"DONE. Received Bytes: %d", [webData length]); NSString *theXML = [[NSString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding]; NSLog(theXML); [theXML release]; if( xmlParser ) { [xmlParser release]; } xmlParser = [[NSXMLParser alloc] initWithData: webData]; [xmlParser setDelegate: self]; [xmlParser setShouldResolveExternalEntities: YES]; [xmlParser parse]; [connection release]; [webData release]; } -(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *) namespaceURI qualifiedName:(NSString *)qName attributes: (NSDictionary *)attributeDict { if( [elementName isEqualToString:@"LoginResult"]) { if(!soapResults) { soapResults = [[NSMutableString alloc] init]; } recordResults = TRUE; } } -(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string { if( recordResults ) { [soapResults appendString: string]; } } -(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName { if( [elementName isEqualToString:@"LoginResult"]) { recordResults = FALSE; ResultString = soapResults; NSLog(@"Login"); [VariableStore setStr:ResultString]; NSLog(soapResults); [soapResults release]; soapResults = nil; } } @end I am calling LoginCheck method and based on result I want to show the second view. Here after finishing of the button touch down event, it enter into did end element, so I am always getting nil value. If I use the same code controller it works fine as I push second view controller in didendelement. Please give me some samples to place the web service calls in differnt class and how to call them in viewcontrollers. Regards, Malleswar

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• python socket related question.

  - by paul

  Hello,All im totally new to socket programming in python. i was read some tutorial and manual, but i didn't found what i want to make python related socket script in manual or tutorial. i want to make socket script which can send some info to server and also receive some info from server. For example, i want to send my login information to server, and want to receive result reply from server. but i have no idea..how to send my login information(id and password) to server. i was captured with wireshark, some process to send login info to server. and i was found port number is 5300 and server ip is 58.225.56.152 and i was send id is 'aaaaaaa' and password 'bbbbbbb' and i was received 'USER NOT FOUND' result from server. how can i make this kind of process with python socket ? if anyone help me some reference or some example or anything help much appreciate! 0000 00 50 56 f2 c8 cc 00 0c 29 a8 f8 c0 08 00 45 00 .PV.....).....E. 0010 00 e2 2a 19 40 00 80 06 d0 55 c0 a8 cb 85 3a e1 ..*[email protected]....:. 0020 38 98 05 f3 15 9a b9 86 62 7b 0d ab 0f ba 50 18 8.......b{....P. 0030 fa f0 26 14 00 00 50 54 3f 09 a2 91 7f 13 00 00 ..&...PT?....... 0040 00 1f 14 00 02 00 00 00 00 00 00 00 07 00 00 00 ................ 0050 61 61 61 61 61 61 61 50 54 3f 09 a2 91 7f 8b 00 aaaaaaaPT?...... 0060 00 00 1f 15 00 08 00 00 00 07 00 00 00 61 61 61 .............aaa 0070 61 61 61 61 07 00 00 00 62 62 62 62 62 62 62 01 aaaa....bbbbbbb. 0080 00 00 00 31 02 00 00 00 4b 52 0f 00 00 00 31 39 ...1....KR....19 0090 32 2e 31 36 38 2e 32 30 33 2e 31 33 33 30 00 00 2.168.203.1330.. 00a0 00 4d 69 63 72 6f 73 6f 66 74 20 57 69 6e 64 6f .Microsoft Windo 00b0 77 73 20 58 50 20 50 72 6f 66 65 73 73 69 6f 6e ws XP Profession 00c0 61 6c 20 53 65 72 76 69 63 65 20 50 61 63 6b 20 al Service Pack 00d0 32 14 00 00 00 31 30 30 31 33 30 30 35 33 31 35 2....10013005315 00e0 37 38 33 37 32 30 31 32 33 03 00 00 00 34 37 30 783720123....470 0000 00 0c 29 a8 f8 c0 00 50 56 f2 c8 cc 08 00 45 00 ..)....PV.....E. 0010 00 28 ae 37 00 00 80 06 8c f1 3a e1 38 98 c0 a8 .(.7......:.8... 0020 cb 85 15 9a 05 f3 0d ab 0f ba b9 86 63 35 50 10 ............c5P. 0030 fa f0 5f 8e 00 00 00 00 00 00 00 00 .._......... 0000 00 0c 29 a8 f8 c0 00 50 56 f2 c8 cc 08 00 45 00 ..)....PV.....E. 0010 00 4c ae 38 00 00 80 06 8c cc 3a e1 38 98 c0 a8 .L.8......:.8... 0020 cb 85 15 9a 05 f3 0d ab 0f ba b9 86 63 35 50 18 ............c5P. 0030 fa f0 3e 75 00 00 50 54 3f 09 a2 91 7f 16 00 00 ..>u..PT?....... 0040 00 1f 18 00 01 00 00 00 0e 00 00 00 55 73 65 72 ............User 0050 20 4e 6f 74 20 46 6f 75 6e 64 Not Found

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• How you remember by default functionality/class name etc of the platform

  - by piemesons

  Hello everyone, I am 8 months experienced guy, (B.tech in computer science) In my college time i used to create simple programs in c/c++/java. Simple programs like creating linked list/binary trees programs. frankly saying those college bullshit exercise.(I am from India so Engg colleges in india sucks except few like IIT's etc). In my college time apart from my college exercises i created some better programs/games like arachnoid, snake. We had 6 months internship in our college curriculum. I worked on asp.net. Basically the work was to create a website with some random functionality. After that in my job i worked on php and successfully deployed 4 projects. All having lot of functionality and i was the only team member in all the projects. Now i am learning ruby on rails as i switched to a new firm. I also have to work on android or iphone depending upon on what mobile technology i want to choose or i can work on both of the technologies. My project manager says take your time to learn things. we are not in hurry to place you in any project. Work on things by your self. take 3 4 months to learn. But i am not getting good pace. I am quite confident with php/asp etc but i dont able to grasp things in android. Although my c/c++ background is quite good, having a good logical mind. But i am not able to grasp the things in android. Even learning some basics of rails i found it wtf. Why i have make model name singular and table name plural.By default that action name and name of the file in view is same I just hate the word MAGIC mentioned more than 100 times in the book. (agile-web-development-with-rails) (I am talking about default functionality, I can over ride them that i know, so please dont debate on that) I not saying i am not getting the things. My point is remembering the default functionality is a pissing me off. Lots of classes. Lots of files . specify this thing here. That thing there. All these things (remember which class does what) require some time or i am missing something. For my point of view i am having all these problems cause previously i never used object oriented programming approach in php. (I NEVER USED, I AM NOT SAYING THET ARE NOT) How you people explain it. How you people suggest me to do. I am looking suggestions from some seniors.From seniors in my office.They says you good dude. But i dont know i am not geting confidence in the things. When they ask me anythings about the topics i cover. I give them good answers. So when i discuss this problem with them they says there is no problem just keep on working. And sorry for my poor english.

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• GCC error with variadic templates: "Sorry, unimplemented: cannot expand 'Identifier...' into a fixe

  - by Dennis

  While doing variadic template programming in C++0x on GCC, once in a while I get an error that says "Sorry, unimplemented: cannot expand 'Identifier...' into a fixed-length arugment list." If I remove the "..." in the code then I get a different error: "error: parameter packs not expanded with '...'". So if I have the "..." in, GCC calls that an error, and if I take the "..." out, GCC calls that an error too. The only way I have been able to deal with this is to completely rewrite the template metaprogram from scratch using a different approach, and (with luck) I eventually come up with code that doesn't cause the error. But I would really like to know what I was doing wrong. Despite Googling for it and despite much experimentation, I can't pin down what it is that I'm doing differently between variadic template code that does produce this error, and code that does not have the error. The wording of the error message seems to imply that the code should work according the C++0x standard, but that GCC doesn't support it yet. Or perhaps it is a compiler bug? Here's some code that produces the error. Note: I don't need you to write a correct implementation for me, but rather just to point out what is about my code that is causing this specific error // Used as a container for a set of types. template <typename... Types> struct TypePack { // Given a TypePack<T1, T2, T3> and T=T4, returns TypePack<T1, T2, T3, T4> template <typename T> struct Add { typedef TypePack<Types..., T> type; }; }; // Takes the set (First, Others...) and, while N > 0, adds (First) to TPack. // TPack is a TypePack containing between 0 and N-1 types. template <int N, typename TPack, typename First, typename... Others> struct TypePackFirstN { // sorry, unimplemented: cannot expand ‘Others ...’ into a fixed-length argument list typedef typename TypePackFirstN<N-1, typename TPack::template Add<First>::type, Others...>::type type; }; // The stop condition for TypePackFirstN: when N is 0, return the TypePack that has been built up. template <typename TPack, typename... Others> struct TypePackFirstN<0, TPack, Others...> //sorry, unimplemented: cannot expand ‘Others ...’ into a fixed-length argument list { typedef TPack type; }; EDIT: I've noticed that while a partial template instantiation that looks like does incur the error: template <typename... T> struct SomeStruct<1, 2, 3, T...> {}; Rewriting it as this does not produce an error: template <typename... T> struct SomeStruct<1, 2, 3, TypePack<T...>> {}; It seems that you can declare parameters to partial specializations to be variadic; i.e. this line is OK: template <typename... T> But you cannot actually use those parameter packs in the specialization, i.e. this part is not OK: SomeStruct<1, 2, 3, T... The fact that you can make it work if you wrap the pack in some other type, i.e. like this: SomeStruct<1, 2, 3, TypePack<T...>> to me implies that the declaration of the variadic parameter to a partial template specialization was successful, and you just can't use it directly. Can anyone confirm this?

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• The best JSF coding pattern for editing JPA entities using @RequestScoped only

  - by AlanObject

  I am in a project where I will write a lot of pages like this, so I want to use the most efficient (to write) coding pattern. Background: In the past I have used CODI's @ViewAccessScoped to preserve state between requests, and more recently I have started using flash scoped objects to save state. I can't use JSF @ViewScoped because I use CDI and they don't play well together. So I want to see if I can do this with only @RequestScoped backing beans. The page is designed like this (the p namespace is Primefaces): <f:metadata> <f:viewParam name="ID" value="#{backing.id}" /> </f:metadata> .... <h1>Edit Object Page</h1> <h:form id="formObj" rendered="#{backing.accessOK}"> <p:panelGrid columns="2"> <h:outputLabel value="Field #1:"/> <p:inputText value="#{backing.record.field1}" /> (more input fields) <h:outputLabel value="Action:" /> <h:panelGroup> <p:commandButton value="Save" action="#{backing.save}" /> <p:commandButton value="Cancel" action="backing.cancel" /> </h:panelGroup> </p:panelGrid> <p:messages showDetail="true" showSummary="true" /> </h:form> If the page is requested, the method accessOK() has the ability to keep the h:form from being rendered. Instead, the p:messages is shown with whatever FacesMessage(s) the accessOK() method cares to set. The pattern for the bean backing looks like this: @Named @RequestScoped public class Backing { private long id; private SomeJPAEntity record; private Boolean accessOK; public long getId() { return id; } public void setId(long value) { id = value; } public boolean accessOK() { if (accessOK != null) return accessOK; if (getRecord() == null) { // add a FacesMessage that explains the record // does not exist return accessOK = false; // note single = } // do any other access checks, such as write permissions return accessOK = true; } public SomeJPAEntity getRecord() { if (record != null) return record; if (getId() > 0) record = // get the record from DB else record = new SomeJPAEntity(); return record; } public String execute() { if (!accessOK()) return null; // bad edit // do other integrity checks here. If fail, set FacesMessages // and return null; if (getId() > 0) // merge the record back into the data base else // persist the record } } Here is what goes wrong with this model. When the Save button is clicked, a new instance of Backing is built, and then there are a lot of calls to the getRecord() getter before the setID() setter is called. So the logic in getRecord() breaks because it cannot rely on the id property being valid when it is called. When this was a @ViewAccessScoped (or ViewScoped) backing bean, then both the id and record properties are already set when the form is processed with the commandButton. Alternatively you can save those properties in flash storage but that has its own problems I want to avoid. So is there a way to make this programming model work within the specification?

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• linux script, standard directory locations.

  - by Thingomy

  I am trying to write a bash script to do a task, I have done pretty well so far, and have it working to an extent, but I want to set it up so it's distributable to other people, and will be opening it up as open source, so I want to start doing things the "conventional" way. Unfortunately I'm not all that sure what the conventional way is. Ideally I want a link to an in depth online resource that discusses this and surrounding topics in depth, but I'm having difficulty finding keywords that will locate this on google. At the start of my script I set a bunch of global variables that store the names of the dirs that it will be accessing, this means that I can modify the dir's quickly, but this is programming shortcuts, not user shortcuts, I can't tell the users that they have to fiddle with this stuff. Also, I need for individual users' settings not to get wiped out on every upgrade. Questions: Name of settings folder: ~/.foo/ -- this is well and good, but how do I keep my working copy and my development copy separate? tweek the reference in the source of the dev version? If my program needs to maintain and update library of data (gps tracklog data in this case) where should this directory be? the user will need to access some of this data, but it's mostly for internal use. I personally work in cygwin, and I like to keep this data on separate drive, so the path is wierd, I suspect many users could find this. for a default however I'm thinking ~/gpsdata/ -- would this be normal, or should I hard code a system that ask the user at first run where to put it, and stores this in the settings folder? whatever happens I'm going ot have to store the directory reference in a file in the settings folder. The program needs a data "inbox" that is a folder that the user can dump files, then run the script to process these files. I was thinking ~/gpsdata/in/ ?? though there will always be an option to add a file or folder to the command line to use that as well (it processed files all locations listed, including the "inbox") Where should the script its self go? it's already smart enough that it can create all of it's ancillary/settings files (once I figure out the "correct" directory) if run with "./foo --setup" I could shove it in /usr/bin/ or /bin or ~/.foo/bin (and add that to the path) what's normal? I need to store login details for a web service that it will connect to (using curl -u if it matters) plan on including a setting whereby it asks for a username and password every execution, but it currently stores it plane text in a file in ~/.foo/ -- I know, this is not good. The webservice (osm.org) does support oauth, but I have no idea how to get curl to use it -- getting curl to speak to the service in the first place was a hack. Is there a simple way to do a really basic encryption on a file like this to deter idiots armed with notepad? Sorry for the list of questions, I believe they are closely related enough for a single post. This is all stuff that stabbing at, but would like clarification/confirmation over.

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• making an array controller the target of a button

  - by ian

  I am working through a chapter of COCOA PROGRAMMING FOR MAC OS X (3RD EDITION) on NSArrayController and it tells me to: Control-Drag to make the array controller become the target of the Add New Employee button. Set the action to add: However when I drag over the array controller it does not highlight so I get no target options. How do I do this correctly in the new XCode full size image document.h: // // Document.h // RaiseMan // // Created by user on 11/12/11. // Copyright (c) 2011 __MyCompanyName__. All rights reserved. // #import <Cocoa/Cocoa.h> @interface Document : NSDocument { NSMutableArray *employees; } @end document.m: // // Document.m // RaiseMan // // Created by user on 11/12/11. // Copyright (c) 2011 __MyCompanyName__. All rights reserved. // #import "Document.h" @implementation Document - (id)init { self = [super init]; if (self) { employees = [[NSMutableArray alloc] init]; } return self; } - (void)dealloc { [self setEmployees:nil]; [super dealloc]; } -(void)setEmployees:(NSMutableArray *)a { //this is an unusual setter method we are goign to ad a lot of smarts in the next chapter if (a == employees) return; [a retain]; [employees release]; employees = a; } - (NSString *)windowNibName { // Override returning the nib file name of the document // If you need to use a subclass of NSWindowController or if your document supports multiple NSWindowControllers, you should remove this method and override -makeWindowControllers instead. return @"Document"; } - (void)windowControllerDidLoadNib:(NSWindowController *)aController { [super windowControllerDidLoadNib:aController]; // Add any code here that needs to be executed once the windowController has loaded the document's window. } - (NSData *)dataOfType:(NSString *)typeName error:(NSError **)outError { /* Insert code here to write your document to data of the specified type. If outError != NULL, ensure that you create and set an appropriate error when returning nil. You can also choose to override -fileWrapperOfType:error:, -writeToURL:ofType:error:, or -writeToURL:ofType:forSaveOperation:originalContentsURL:error: instead. */ NSException *exception = [NSException exceptionWithName:@"UnimplementedMethod" reason:[NSString stringWithFormat:@"%@ is unimplemented", NSStringFromSelector(_cmd)] userInfo:nil]; @throw exception; return nil; } - (BOOL)readFromData:(NSData *)data ofType:(NSString *)typeName error:(NSError **)outError { /* Insert code here to read your document from the given data of the specified type. If outError != NULL, ensure that you create and set an appropriate error when returning NO. You can also choose to override -readFromFileWrapper:ofType:error: or -readFromURL:ofType:error: instead. If you override either of these, you should also override -isEntireFileLoaded to return NO if the contents are lazily loaded. */ NSException *exception = [NSException exceptionWithName:@"UnimplementedMethod" reason:[NSString stringWithFormat:@"%@ is unimplemented", NSStringFromSelector(_cmd)] userInfo:nil]; @throw exception; return YES; } + (BOOL)autosavesInPlace { return YES; } - (void)setEmployees:(NSMutableArray *)a; @end person.h: // // Person.h // RaiseMan // // Created by user on 11/12/11. // Copyright (c) 2011 __MyCompanyName__. All rights reserved. // #import <Foundation/Foundation.h> @interface Person : NSObject { NSString *personName; float expectedRaise; } @property (readwrite, copy) NSString *personName; @property (readwrite) float expectedRaise; @end person.m: // // Person.m // RaiseMan // // Created by user on 11/12/11. // Copyright (c) 2011 __MyCompanyName__. All rights reserved. // #import "Person.h" @implementation Person - (id) init { self = [super init]; expectedRaise = 5.0; personName = @"New Person"; return self; } - (void)dealloc { [personName release]; [super dealloc]; } @synthesize personName; @synthesize expectedRaise; @end

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• hello-1.mod.c:14: warning: missing initializer (near initialization for '__this_module.arch.unw_sec_init')

  - by Sompom

  I am trying to write a module for an sbc1651. Since the device is ARM, this requires a cross-compile. As a start, I am trying to compile the "Hello Kernel" module found here. This compiles fine on my x86 development system, but when I try to cross-compile I get the below error. /home/developer/HelloKernel/hello-1.mod.c:14: warning: missing initializer /home/developer/HelloKernel/hello-1.mod.c:14: warning: (near initialization for '__this_module.arch.unw_sec_init') Since this is in the .mod.c file, which is autogenerated I have no idea what's going on. The mod.c file seems to be generated by the module.h file. As far as I can tell, the relevant parts are the same between my x86 system's module.h and the arm kernel header's module.h. Adding to my confusion, this problem is either not googleable (by me...) or hasn't happened to anyone before. Or I'm just doing something clueless that anyone with any sense wouldn't do. The cross-compiler I'm using was supplied by Freescale (I think). I suppose it could be a problem with the compiler. Would it be worth trying to build the toolchain myself? Obviously, since this is a warning, I could ignore it, but since it's so strange, I am worried about it, and would like to at least know the cause... Thanks very much, Sompom Here are the source files hello-1.mod.c #include <linux/module.h> #include <linux/vermagic.h> #include <linux/compiler.h> MODULE_INFO(vermagic, VERMAGIC_STRING); struct module __this_module __attribute__((section(".gnu.linkonce.this_module"))) = { .name = KBUILD_MODNAME, .init = init_module, #ifdef CONFIG_MODULE_UNLOAD .exit = cleanup_module, #endif .arch = MODULE_ARCH_INIT, }; static const struct modversion_info ____versions[] __used __attribute__((section("__versions"))) = { { 0x3972220f, "module_layout" }, { 0xefd6cf06, "__aeabi_unwind_cpp_pr0" }, { 0xea147363, "printk" }, }; static const char __module_depends[] __used __attribute__((section(".modinfo"))) = "depends="; hello-1.c (modified slightly from the given link) /* hello-1.c - The simplest kernel module. * * Copyright (C) 2001 by Peter Jay Salzman * * 08/02/2006 - Updated by Rodrigo Rubira Branco <[email protected]> */ /* Kernel Programming */ #ifndef MODULE #define MODULE #endif #ifndef LINUX #define LINUX #endif #ifndef __KERNEL__ #define __KERNEL__ #endif #include <linux/module.h> /* Needed by all modules */ #include <linux/kernel.h> /* Needed for KERN_ALERT */ static int hello_init_module(void) { printk(KERN_ALERT "Hello world 1.\n"); /* A non 0 return means init_module failed; module can't be loaded.*/ return 0; } static void hello_cleanup_module(void) { printk(KERN_ALERT "Goodbye world 1.\n"); } module_init(hello_init_module); module_exit(hello_cleanup_module); MODULE_LICENSE("GPL"); Makefile export ARCH:=arm export CCPREFIX:=/opt/freescale/usr/local/gcc-4.4.4-glibc-2.11.1-multilib-1.0/arm-fsl-linux-gnueabi/bin/arm-linux- export CROSS_COMPILE:=${CCPREFIX} TARGET := hello-1 WARN := -W -Wall -Wstrict-prototypes -Wmissing-prototypes -Wno-sign-compare -Wno-unused -Werror UNUSED_FLAGS := -std=c99 -pedantic EXTRA_CFLAGS := -O2 -DMODULE -D__KERNEL__ ${WARN} ${INCLUDE} KDIR ?= /home/developer/src/ltib-microsys/ltib/rpm/BUILD/linux-2.6.35.3 ifneq ($(KERNELRELEASE),) # kbuild part of makefile obj-m := $(TARGET).o else # normal makefile default: clean $(MAKE) -C $(KDIR) M=$$PWD .PHONY: clean clean: -rm built-in.o -rm $(TARGET).ko -rm $(TARGET).ko.unsigned -rm $(TARGET).mod.c -rm $(TARGET).mod.o -rm $(TARGET).o -rm modules.order -rm Module.symvers endif

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• What am I doing wrong?, linking in C++

  - by Facon

  I'm trying to code a simple base64 encoder/decoder (to test my programming skill). I can compile it, but it doesn't link, I've this message error: C:\Documents and Settings\Facon\Escritoriog++ base64.o main.o -o prueba.exe main.o:main.cpp:(.text+0x24a): undefined reference to `Base64Encode(std::vector const&)' collect2: ld returned 1 exit status Compiler & Linker: Mingw32 3.4.5 SO: Windows XP This is my source code: base64.h: #ifndef BASE64_H #define BASE64_H #include <iostream> #include <vector> typedef unsigned char byte; std::string Base64Encode(const std::vector<byte> &array); std::vector<byte> Base64Decode(const std::string &array); #endif base64.cpp: #include "base64.h" std::string Base64Encode(std::vector<byte> &array) { const char *base64_table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; const unsigned int size = array.size(); std::string output; for (unsigned int i = 0; (i < size); i++) { if ((size - i) > 3) { output.push_back(static_cast<char>(base64_table[array[i] >> 2])); output.push_back(static_cast<char>(base64_table[((array[i++] & 0x03) << 4) | ((array[i] & 0xF0) >> 4)])); output.push_back(static_cast<char>(base64_table[((array[i++] & 0x0F) << 2) | ((array[i] & 0xC0) >> 4)])); output.push_back(static_cast<char>(base64_table[array[i] & 0x3F])); } else if ((size - i) == 3) { output.push_back(static_cast<char>(base64_table[array[i] >> 2])); output.push_back(static_cast<char>(base64_table[((array[i++] & 0x03) << 4) | ((array[i] & 0xF0) >> 4)])); output.push_back(static_cast<char>(base64_table[(array[i] & 0x0F) << 2])); output.push_back(static_cast<char>('=')); } else if ((size - i) == 2) { output.push_back(static_cast<char>(base64_table[array[i] >> 2])); output.push_back(static_cast<char>(base64_table[(array[i] & 0x03) << 4])); output.push_back('='); output.push_back('='); } } return output; } std::vector<byte> Base64Decode(const std::string &array) // TODO { const char *base64_table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; } main.cpp: #include <iostream> #include <vector> #include "base64.h" using namespace std; int main(int argc, char *argv[]) { const char* prueba = "sure."; vector<byte> texto; string codificado; for (unsigned int i = 0; (prueba[i] != 0); i++) { texto.push_back(prueba[i]); } codificado = Base64Encode(texto); cout << codificado; return 0; } PD: Sorry for my bad knowledge of English :P

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• Facelet components layouts and javascript

  - by Java Drinker

  Hi all, I have a question regarding the placement of javascript within facelet components. This is more regarding best practice/style than a programming issue, but I feel like all the solutions I have thought of have been hacks at best. Ok here is my scenario: I have a facelet template like so (my faces, and apache Trinidad)... <ui:composition> <f:view locale="#{myLocale}"> <ui:insert name="messageBundles" /><!--Here we add load bundle tags--> <tr:document mode="strict" styleClass="coolStyleDoc"> <f:facet name="metaContainer"> <!--This trinidad defined facet is added to HTML head--> <tr:group> <!-- blah bal my own styles and js common to all --> <ui:insert name="metaData" /> </tr:group> </f:facet> <tr:form usesUpload="#{empty usesUpload ? 'false' : usesUpload}"> <div id="formTemplateHeader"> <ui:insert name="contentHeader" /> </div> <div id="formTemplateContentContainer"> <div id="formTemplateContent"> <ui:insert name="contentBody" /> </div> </div> <div id="formTemplateFooter"> <ui:insert name="contentFooter"> </ui:insert> </div> </tr:form> <!-- etc...---> Now, a facelet that wants to use this template would look like the following: <ui:composition template="/path/to/my/template.jspx"> <ui:define name="bundles"> <custom:loadBundle basename="messagesStuff" var="bundle" /> </ui:define> <ui:define name="metaData"> <script> <!-- cool javascript stuff goes here--> </script> </ui:define> <ui:define name="contentHeader"> <!-- MY HEADING!--> </ui:define> <ui:define name="contentBody"> <!-- MY Body!--> </ui:define> <ui:define name="contentFooter"> <!-- Copyright/footer stuff!--> </ui:define> </ui:composition> All this works quite well, but the problem I have is when I want to use a facelet component inside this page. If the facelet component has its own javascript code (jQuery stuff etc), how can I make it so that that javascript code is included in the header section of the generated html? Any help would be appreciated. Please let me know if this is not clear or something... thanks in advance

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