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  • Vector insert() causes program to crash

    - by wrongusername
    This is the first part of a function I have that's causing my program to crash: vector<Student> sortGPA(vector<Student> student) { vector<Student> sorted; Student test = student[0]; cout << "here\n"; sorted.insert(student.begin(), student[0]); cout << "it failed.\n"; ... It crashes right at the sorted part because I can see "here" on the screen but not "it failed." The following error message comes up: Debug Assertion Failed! (a long path here...) Expression: vector emplace iterator outside range For more information on how your program can cause an assertion failure, see the Visual C++ documentation on asserts. I'm not sure what's causing the problem now, since I have a similar line of code elsewhere student.insert(student.begin() + position(temp, student), temp); that does not crash (where position returns an int and temp is another declaration of a struct Student). What can I do to resolve the problem, and how is the first insert different from the second one?

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  • Web development scheme for staging and production servers using Git Push

    - by ServAce85
    I am using git to manage a dynamic website (PHP + MySQL) and I want to send my files from my localhost to my staging and development servers in the most efficient and hassle-free way. I am currently convinced that the best way for me to approach this problem is to use this git branching model to organize my local git repo. From there, I will use the release branches to push to my staging server for testing. Once I am happy that the release code works on the staging server, I can then merge with my master branch and push that to my production server. Pushing to Staging Server: As noted in many introductory git posts, I could run into problems pushing into a non-bare repo, so, as suggested in this response, I plan to push the release branch to a bare repo on the server and have a post-receive hook that clones the bare repo to a non-bare repo that also acts as the web-hosted directory. Pushing to Production Server: Here's my newest source of confusion... In the response that I cited above, it made me curious as to why @Paul states that it's a completely different story when pushing to a live, development server. I guess I don't see the problem. Would it be safe and hassle-free to follow the same steps as above, but for the master branch? Where are the potential pit-falls? Config Files: With respect to configuration files that are unique to each environment (.htaccess, config.php, etc), it seems simplest to .gitignore each of those files in their respective repos on their respective servers. Can you see anything immediately wrong with this? Better solutions? Accessing Data: Finally, as I initially stated, the site uses MySQL databases to store data. How would you suggest I access that data (for testing purposes) from the staging server and localhost? I realize that I may have asked way too many questions for a single post, but since they're all related to the best way to set up this development scheme, I thought it was necessary.

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  • Comparison operators not supported for type IList when Paging data in Linq to Sql

    - by Dan
    I can understand what the error is saying - it can't compare a list. Not a problem, other than the fact that I don't know how to not have it compare a list when I want to page through a model with a list as a property. My Model: Event : IEvent int Id string Title // Other stuff.. LazyList<EventDate> Dates // The "problem" property Method which pages the data (truncated): public JsonResult JsonEventList(int skip, int take) { var query = _eventService.GetEvents(); // Do some filtering, then page data.. query = query.Skip(skip).Take(take); return Json(query.ToArray()); } As I said, the above is truncated quite a bit, leaving only the main point of the function: filter, page and return JSON'd data. The exception occurs when I enumerate (.ToArray()). The Event object is really only used to list the common objects of all the event types (Meetings, Birthdays, etc - for example). It still implements IEvent like the other types, so I can't just remove the LazyList<EventDate> Dates' property unless I no longer implementIEvent` Anyway, is there a way to avoid this? I don't really want to compare a LazyList when I page, but I do not know how to resolve this issue. Thank you in advance! :)

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  • Weak hashmap with weak references to the values?

    - by Razor Storm
    I am building an android app where each entity has a bitmap that represents its sprite. However, each entity can be be duplicated (there might be 3 copies of entity asdf for example). One approach is to load all the sprites upfront, and then put the correct sprite in the constructors of the entities. However, I want to decode the bitmaps lazily, so that the constructors of the entities will decode the bitmaps. The only problem with this is that duplicated entities will load the same bitmap twice, using 2x the memory (Or n times if the entity is created n times). To fix this, I built a SingularBitmapFactory that will store a decoded Bitmap into a hash, and if the same bitmap is asked for again, will simply return the previously hashed one instead of building a new one. Problem with this, though, is that the factory holds a copy of all bitmaps, and so won't ever get garbage collected. What's the best way to switch the hashmap to one with weakly referenced values? In otherwords, I want a structure where the values won't be GC'd if any other object holds a reference to it, but as long as no other objects refers it, then it can be GC'd.

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  • Is there a fundamental difference between malloc and HeapAlloc (aside from the portability)?

    - by Lambert
    Hi, I'm having code that, for various reasons, I'm trying to port from the C runtime to one that uses the Windows Heap API. I've encountered a problem: If I redirect the malloc/calloc/realloc/free calls to HeapAlloc/HeapReAlloc/HeapFree (with GetProcessHeap for the handle), the memory seems to be allocated correctly (no bad pointer returned, and no exceptions thrown), but the library I'm porting says "failed to allocate memory" for some reason. I've tried this both with the Microsoft CRT (which uses the Heap API underneath) and with another company's run-time library (which uses the Global Memory API underneath); the malloc for both of those works well with the library, but for some reason, using the Heap API directly doesn't work. I've checked that the allocations aren't too big (= 0x7FFF8 bytes), and they're not. The only problem I can think of is memory alignment; is that the case? Or other than that, is there a fundamental difference between the Heap API and the CRT memory API that I'm not aware of? If so, what is it? And if not, then why does the static Microsoft CRT (included with Visual Studio) take some extra steps in malloc/calloc before calling HeapAlloc? I'm suspecting there's a difference but I can't think of what it might be. Thank you!

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  • How can I get vim to draw lines correctly for remote editing?

    - by Rick Reynolds
    I'm attempting to edit files on a remote system. I've ssh'd to the system and I start editing with vim. However, I notice that all the lines are drawing 2 lines above where they really exist in the file. I assumed this was a problem I could fix by dropping my terminal settings to something simpler, but that didn't help. My TERM variable was set to xterm-color. I set it to vt100, but that didn't fix the line drawing issue. I also noticed that this seems to be specific to vim. emacs doesn't show the problem, and I haven't noticed any odd drawing artifacts in less, more or other paging tools. Other specifics: I'm ssh-ing into the remote system from a Mac, using the Terminal.app. The remote system is running Ubuntu 9.04. I'm hoping there is something I just need to set in vim to get it to play nice. If it allows me to keep syntax color highlighting, so much the better.

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  • Why is Delphi unable to infer the type for a parameter TEnumerable<T>?

    - by deepc
    Consider the following declaration of a generic utility class in Delphi 2010: TEnumerableUtils = class public class function InferenceTest<T>(Param: T): T; class function Count<T>(Enumerable: TEnumerable<T>): Integer; overload; class function Count<T>(Enumerable: TEnumerable<T>; Filter: TPredicate<T>): Integer; overload; end; Somehow the compiler type inference seems to have problems here: var I: Integer; L: TList<Integer>; begin TEnumerableUtils.InferenceTest(I); // no problem here TEnumerableUtils.Count(L); // does not compile: E2250 There is no overloaded version of 'Count' that can be called with these arguments TEnumerableUtils.Count<Integer>(L); // compiles fine end; The first call works as expected and T is correctly inferred as Integer. The second call does not work, unless I also add <Integer -- then it works, as can be seen in the third call. Am I doing something wrong or is the type inference in Delphi just not supporting this (I don't think it is a problem in Java which is why expected it to work in Delphi, too).

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  • C# Breakpoint Weirdness

    - by Dan
    In my program I've got two data files A and B. The data in A is static and the data in B refers back to the data in A. In order to make sure the data in B is invalidated when A is changed, I keep an identifier for each of the links which is a long byte-string identifying the data. I get this string using BitConverter on some of the important properties. My problem is that this scheme isn't working. I save the identifiers initially, and with I reload (with the exact same data in A) the identifiers don't match anymore. It seems the bit converter gives different results when I go to save. The really weird thing about it is, if I place a breakpoint in the save code, I can see the identifier it's writing to the file is fine, and the next load works. If I don't place a breakpoint and say print the identifiers to console instead, they're totally different. It's like when my program is running at full-speed the CPU messes up some instructions. This isn't the first time something like this happens to me. I've seen it in other projects. What gives? Has anyone every experienced this kind of debugging weirdness? I can't explain how stopping the program and not stopping it can change the output. Also, it's not a hardware problem because this happens on my laptop as well.

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  • Why can't I extract a C++ type from a Python type using boost::python::extractor?

    - by Robin
    I've wrapped a C++ class using Py++ and everything is working great in Python. I can instantiate the c++ class, call methods, etc. I'm now trying to embed some Python into a C++ application. This is also working fine for the most-part. I can call functions on a Python module, get return values, etc. The python code I'm calling returns one of the classes that I wrapped: import _myextension as myext def run_script(arg): my_cpp_class = myext.MyClass() return my_cpp_class I'm calling this function from C++ like this: // ... excluding error checking, ref counting, etc. for brevity ... PyObject *pModule, *pFunc, *pArgs, *pReturnValue; Py_Initialize(); pModule = PyImport_Import(PyString_FromString("cpp_interface")); pFunc = PyObject_GetAttrString(pModule, "run_script"); pArgs = PyTuple_New(1); PyTuple_SetItem(pArgs, 0, PyString_FromString("an arg")); pReturnValue = PyObject_CallObject(pFunc, pArgs); bp::extract< MyClass& > extractor(pReturnValue); // PROBLEM IS HERE if (extractor.check()) { // This check is always false MyClass& cls = extractor(); } The problem is the extractor never actually extracts/converts the PyObject* to MyClass (i.e. extractor.check() is always false). According to the docs this is the correct way to extract a wrapped C++ class. I've tried returning basic data types (ints/floats/dicts) from the Python function and all of them are extracted properly. Is there something I'm missing? Is there another way to get the data and cast to MyClass?

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  • Declaration, allocation and assignment of an array of pointers to function pointers

    - by manneorama
    Hello Stack Overflow! This is my first post, so please be gentle. I've been playing around with C from time to time in the past. Now I've gotten to the point where I've started a real project (a 2D graphics engine using SDL, but that's irrelevant for the question), to be able to say that I have some real C experience. Yesterday, while working on the event system, I ran into a problem which I couldn't solve. There's this typedef, //the void parameter is really an SDL_Event*. //but that is irrelevant for this question. typedef void (*event_callback)(void); which specifies the signature of a function to be called on engine events. I want to be able to support multiple event_callbacks, so an array of these callbacks would be an idea, but do not want to limit the amount of callbacks, so I need some sort of dynamic allocation. This is where the problem arose. My first attempt went like this: //initial size of callback vector static const int initial_vecsize = 32; //our event callback vector static event_callback* vec = 0; //size static unsigned int vecsize = 0; void register_event_callback(event_callback func) { if (!vec) __engine_allocate_vec(vec); vec[vecsize++] = func; //error here! } static void __engine_allocate_vec(engine_callback* vec) { vec = (engine_callback*) malloc(sizeof(engine_callback*) * initial_vecsize); } First of all, I have omitted some error checking as well as the code that reallocates the callback vector when the number of callbacks exceed the vector size. However, when I run this code, the program crashes as described in the code. I'm guessing segmentation fault but I can't be sure since no output is given. I'm also guessing that the error comes from a somewhat flawed understanding on how to declare and allocate an array of pointers to function pointers. Please Stack Overflow, guide me.

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  • Determining when stringByEvaluatingJavaScriptFromString has finished

    - by alku83
    I have a UIWebView which loads up an HTML page. This page has two buttons on it, say Exit and Submit. I don't want users to be able to click the Exit button, so once the page has finished loading (ie. webViewDidFinishLoad is called), I use stringByEvaluatingJavaScriptFromString to remove one of these buttons, by manipulating the HTML. I also disable user interaction on the UIWebView on webViewDidStartLoad, and enable it again on webViewDidFinishLoad. The problem I am finding is that stringByEvaluatingJavaScriptFromString takes a second or two to complete, and it seems to be done in it's own thread. So what is happening is that webViewDidFinishLoad is called, user interaction is enabled on the UIWebView, and if the user is quick, they can click the Exit button before stringByEvaluatingJavaScriptFromString has finished. As stringByEvaluatingJavaScriptFromString seems to be on it's own thread with no way to know when it's finished (it doesnt call webViewDidFinishLoad), the only way to completely prevent users from tapping the Exit button that I can see is to only enable user interaction on the UIWebView after some delay, which is unreliable (how can I really know how long to delay for?). Am I correct in that stringByEvaluatingJavaScriptFromString is done on it's on thread, and I have no way of being able to tell when it's finished? Any other suggestions for how to get around this problem? EDIT: In short, what I want to know is if it is possible to disable a UIWebView while stringByEvaluatingJavaScriptFromString is executing, and re-enable the UIWebView when the javascript is finished. EDIT 2: There's an article here which seems to imply you can somehow poll the JS engine to see when it's finished, but I can't find any other references saying the same thing: http://drnicwilliams.com/2008/11/10/to-webkit-or-not-to-webkit-within-your-iphone-app/ EDIT 3 Based on the answer from Brad Smith, it seems that I actually need to know when the UIWebView has finished loading itself after the javascript has executed. It's looking more and more like I just need to put a delay of sorts in there.

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  • Are function-local typedefs visible inside C++0x lambdas?

    - by GMan - Save the Unicorns
    I've run into a strange problem. The following simplified code reproduces the problem in MSVC 2010 Beta 2: template <typename T> struct dummy { static T foo(void) { return T(); } }; int main(void) { typedef dummy<bool> dummy_type; auto x = [](void){ bool b = dummy_type::foo(); }; // auto x = [](void){ bool b = dummy<bool>::foo(); }; // works } The typedef I created locally in the function doesn't seem to be visible in the lambda. If I replace the typedef with the actual type, it works as expected. Here are some other test cases: // crashes the compiler, credit to Tarydon int main(void) { struct dummy {}; auto x = [](void){ dummy d; }; } // works as expected int main(void) { typedef int integer; auto x = [](void){ integer i = 0; }; } I don't have g++ 4.5 available to test it, right now. Is this some strange rule in C++0x, or just a bug in the compiler? From the results above, I'm leaning towards bug. Though the crash is definitely a bug. For now, I have filed two bug reports. All code snippets above should compile. The error has to do with using the scope resolution on locally defined scopes. (Spotted by dvide.) And the crash bug has to do with... who knows. :) Update According to the bug reports, they have both been fixed for the next release of Visual Studio 2010.

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  • Framework or design pattern for mailing all users of a webapp

    - by Todd Owen
    My app takes care of user registration (with the option to receive email announcements), and can easily handle the actual template-based rendering of email for a given user. JavaMail provides the mail transport layer. But how should I design the application layer between the business objects (e.g. User) and the mail transport? The straightforward approach would be a simple, synchronous loop: iterate through the users, queue the emails, and be done with it. "Queue" might mean sending them straight to the MTA (mail server), or to an in-memory queue to be consumed by another thread. However, I also plan to implement features like throttling the rate of emails, processing bounced emails (NDRs), and maintaining status across application restarts. My intuition is that a good design would decouple this from both the business layer and the mail transport layer as much as possible. I wondered if others had solved this problem before, but after much searching I haven't found any Java libraries which seem to fit this problem. Standalone mail apps such as James or list servers are too large in scope; packages like Spring's MailSender or Commons Email are too small in scope (being basically drop-in replacements for JavaMail). For other languages I haven't found anything appropriate either. I'm curious about how other developers have gone about adding bulk mailing to their applications.

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  • Client-side validation breaks in IE because of PropertyProxyValidator and ScriptManager cooperation.

    - by Eugene
    The specific of the project is in using Enterpise Library for Server side validation and jQuery for client-side validation. So I have the next simple form for example: <asp:Content ID="_mainContent" ContentPlaceHolderID="MainContent" runat="server"> <script src="../../../Scripts/jquery-1.3.2.js" type="text/javascript"></script> <script src="../../../Scripts/jquery.validate.js" type="text/javascript"></script> <script type="text/javascript"> $(document).ready(function() { $("#aspnetForm").validate({ rules: { "<%= _txtProjectName.UniqueID %>": { required: true } } }); }); </script> <asp:TextBox ID="_txtProjectName" runat="server" CssClass="textBoxWithValidator_long" /> <entlib:PropertyProxyValidator id="_validatorProjectName" runat="server" ControlToValidate="_txtProjectName" PropertyName="ProjectName" SourceTypeName="LabManagement.Project.Project" /> <asp:Button CssClass="cell_InlineElement" ID="_btnSave" runat="server" Text="Save" onclick="_btnSave_Click" Width="50px" /> <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true"> </asp:ScriptManager> </asp:Content> The problem is in the next: client-side validation worked correctly before I needed to implement some AJAX.NET feature. So I have to add to the page ScriptManager (the last two lines in the code). But after that the next situation appeared: In InternetExplorer((7) - only in IE !!! - in Firefox everything works correctly) after clicking save button, if left the textbox ProjectName empty the client-side jquery validation appears but (!) the page submits to the server anyway. Some notes: If delete PropertyProxyValidator from the page - the client-side validation works correctly in IE but I need it for specific of the project. It seems that the problem is in the function WebForm_OnSubmit() that is inserted to the form after PropertyProxyValidator adding. ( ... <form name="aspnetForm" method="post" action="Project.aspx?TransType=NewProject" onsubmit="javascript:return WebForm_OnSubmit();" ...>) Could anyone help, please.

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  • Wrong answer on c# application, finding the n prime of a list of prime numbers.

    - by user300484
    Hello, I am new to C# and I am practicing by trying to solve this easy C# problem. This application will receive an "n" number. After receiving this number, the program has to show the n prime of the list of primes. For example, if the user enters "3", the program is supposed to display "5", because 5 is the third prime starting at 2. I koow that something is wrong with my code but I dont know where is the problem and how I can fix it. Can you please tell me? Thank you :P using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { Console.WriteLine("Determinar el n-esimo primo."); long n = Convert.ToInt64(Console.ReadLine()); // N lugar de primos long[] array = new long[n]; long c=0; while (c >= 2) { if(siprimo(c++) == true) for (long i = 0; i < n; i++) { array[i] = c; } } Console.WriteLine(array[n - 1]); Console.ReadLine(); } static private bool siprimo(long x) { bool sp = true; for (long k = 2; k <= x / 2; k++) if (x % k == 0) sp = false; return sp; } } }

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  • Liskov Substition and Composition

    - by FlySwat
    Let say I have a class like this: public sealed class Foo { public void Bar { // Do Bar Stuff } } And I want to extend it to add something beyond what an extension method could do....My only option is composition: public class SuperFoo { private Foo _internalFoo; public SuperFoo() { _internalFoo = new Foo(); } public void Bar() { _internalFoo.Bar(); } public void Baz() { // Do Baz Stuff } } While this works, it is a lot of work...however I still run into a problem: public void AcceptsAFoo(Foo a) I can pass in a Foo here, but not a super Foo, because C# has no idea that SuperFoo truly does qualify in the Liskov Substitution sense...This means that my extended class via composition is of very limited use. So, the only way to fix it is to hope that the original API designers left an interface laying around: public interface IFoo { public Bar(); } public sealed class Foo : IFoo { // etc } Now, I can implement IFoo on SuperFoo (Which since SuperFoo already implements Foo, is just a matter of changing the signature). public class SuperFoo : IFoo And in the perfect world, the methods that consume Foo would consume IFoo's: public void AcceptsAFoo(IFoo a) Now, C# understands the relationship between SuperFoo and Foo due to the common interface and all is well. The big problem is that .NET seals lots of classes that would occasionally be nice to extend, and they don't usually implement a common interface, so API methods that take a Foo would not accept a SuperFoo and you can't add an overload. So, for all the composition fans out there....How do you get around this limitation? The only thing I can think of is to expose the internal Foo publicly, so that you can pass it on occasion, but that seems messy.

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  • Saving animated GIFs using urllib.urlopen (image saved does not animate)

    - by wenbert
    I have Apache2 + Django + X-sendfile. My problem is that when I upload an animated GIF, it won't "animate" when I output through the browser. Here is my code to display the image located outside the public accessible directory. def raw(request,uuid): target = str(uuid).split('.')[:-1][0] image = Uploads.objects.get(uuid=target) path = image.path filepath = os.path.join(path,"%s.%s" % (image.uuid,image.ext)) response = HttpResponse(mimetype=mimetypes.guess_type(filepath)) response['Content-Disposition']='filename="%s"'\ %smart_str(image.filename) response["X-Sendfile"] = filepath response['Content-length'] = os.stat(filepath).st_size return response UPDATE It turns out that it works. My problem is when I try to upload an image via URL. It probably doesn't save the entire GIF? def handle_url_file(request): """ Open a file from a URL. Split the file to get the filename and extension. Generate a random uuid using rand1() Then save the file. Return the UUID when successful. """ try: file = urllib.urlopen(request.POST['url']) randname = rand1(settings.RANDOM_ID_LENGTH) newfilename = request.POST['url'].split('/')[-1] ext = str(newfilename.split('.')[-1]).lower() im = cStringIO.StringIO(file.read()) # constructs a StringIO holding the image img = Image.open(im) filehash = checkhash(im) image = Uploads.objects.get(filehash=filehash) uuid = image.uuid return "%s" % (uuid) except Uploads.DoesNotExist: img.save(os.path.join(settings.UPLOAD_DIRECTORY,(("%s.%s")%(randname,ext)))) del img filesize = os.stat(os.path.join(settings.UPLOAD_DIRECTORY,(("%s.%s")%(randname,ext)))).st_size upload = Uploads( ip = request.META['REMOTE_ADDR'], filename = newfilename, uuid = randname, ext = ext, path = settings.UPLOAD_DIRECTORY, views = 1, bandwidth = filesize, source = request.POST['url'], size = filesize, filehash = filehash, ) upload.save() #return uuid return "%s" % (upload.uuid) except IOError, e: raise e Any ideas? Thanks! Wenbert

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  • How to disable server-side caching on IIS 7.5 (asp net mvc3)

    - by troebr
    I'm struggling with my IIS setup regarding caching, here's a brief description of my problem: I'm making a site for mobile and non-mobile, sharing the same controllers. IE: mysite/page will serve either mysite/page.cshtml, or mysite/M/page.cshtml, depending on the device. Here's the catch, it worked fine with my local and integration environment (cassiini and iis 6), but on another machine (2008r2/iis 7.5), apparently there is an aggressive server-side caching policy: If I access the website from a desktop machine, I have the correct pages (desktop version) If now I use my mobile phone to access the site, I will have the desktop version, (which implies a server-side cache, my phone is not using the same network). On the contrary, if I were to restart the server and access the site using my phone first, then I will get the mobile version on my desktop (only for the pages I already visited of course). I tried 2 solutions so far: Disabling OutputCache from my Web.config: <httpModules> [..] <remove name="OutputCache" /> </httpModules> And unchecking "Enable output cache" in "Output Caching" for my site in IIS. What's bugging me is that I do not have this problem with my other server (iis 6.0), although caching is enabled on this one, which leads me to think it is related to iis 7 caching addition. My question is simple: how does one disable server-side caching on IIS 7.5? Thanks in advance for your iis lights!

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  • Tomcat deploy: make included scripts executable

    - by AlexS
    I'm devellopping a WebApplication (for Tomcat) using netbeans on Windows 7. For the Webapplication to run I need to run a insall-script once. This script (*.bat for windows and *.sh for linux is included in my war-file (WEB_INF). Now everytime I deploy the WAR-file and want to run the script on linux I have to call chmod +x install.sh first. Is there a way that this script can be made executable by default? I don't want to have to execute some extra commands after the deploy to make the script executable. For clarification: I'm not new to Linux and I know how to set executable-rights on files. That's not the problem. My problem is: What do I have to do, so that this script is executable right after tomcat deployed my *.war-file (unpacked it). If I would be using Linux for development as well, I would try to set the rights according in my sources (maybe I'll try it when I have a little more spare time). But I am using Windows and netbeans. Are there any attributes I can set to achive my goal, or is it possible to achive this using ant? By the way: Are there security related issues with this approach? The script looks for java executable and calls a javabased GUI-installer...

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  • Serializing and deserializing a map with key as string

    - by Grace K
    Hi! I am intending to serialize and deserialize a hashmap whose key is a string. From Josh Bloch's Effective Java, I understand the following. P.222 "For example, consider the case of a harsh table. The physical representation is a sequence of hash buckets containing key-value entries. Which bucket an entry is placed in is a function of the hash code of the key, which is not, in general guaranteed to be the same from JVM implementation to JVM implementation. In fact, it isn't even guranteed to be the same from run to run on the same JVM implementation. Therefore accepting the default serialized form for a hash table would constitute a serious bug. Serializing and deserializing the hash table could yield an object whose invariants were seriously corrupt." My questions are: 1) In general, would overriding the equals and hashcode of the key class of the map resolve this issue and the map can be correctly restored? 2) If my key is a String and the String class is already overriding the hashCode() method, would I still have problem described above. (I am seeing a bug which makes me think this is probably still a problem even though the key is String with overriding hashCode.) 3)Previously, I get around this issue by serializing an array of entries (key, value) and when deserializing I would reconstruct the map. I am wondering if there is a better approach. 4) If the answers to question 1 and 2 are that I still can't be guaranteed. Could someone explain why? If the hashCodes are the same would they go to the same buckets across JVMs? Thanks, Grace

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  • How to detect that the internet connection has got disconnected through a java desktop application?

    - by Yatendra Goel
    I am developing a Java Desktop Application that access internet. It is a multi-threaded application, each thread do the same work (means each thread is an instance of same Thread class). Now, as all the threads need internet connection to be active, there should be some mechanism that detects whether an internet connection is active or not. Q1. How to detect whether the internet connection is active or not? Q2. Where to implement this internet-status-check-mechanism code? Should I start a separate thread for checking internet status regularly and notifies all the threads when the status changes from one state to another? Or should I let each thread check for the internet-status itself? Q3. This issue should be a very common issue as every application accessing an internet should deal with this problem. So how other developers usually deal with this problem? Q4. If you could give me a reference to a good demo application that addresses this issue then it would greatly help me.

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  • How to get to the key name of a referenced entity property from an entity instance without a datastore read in google app engine?

    - by Sumeet Pareek
    Consider I have the following models - class Team(db.Model): # say I have just 5 teams name = db.StringProperty() class Player(db.Model): # say I have thousands of players name = db.StringProperty() team = db.ReferenceProperty(Team, collection_name="player_set") Key name for each Team entity = 'team_' , and for each Player entity = 'player_' By some prior arrangement I have a Team entity's (key_name, name) mapping available to me. For example (team_01, United States Of America), (team_02, Russia) etc I have to show all the players and their teams on a page. One way of doing this would be - players = Player.all().fetch(1000) # This is 1 DB read for player in players: # This will iterate 1000 times self.response.out.write(player.name) # This is obviously not a DB read self.response.out.write(player.team.name) #This is a total of 1x1000 = 1000 DB reads That is a 1001 DB reads for a silly thing. The interesting part is that when I do a db.to_dict() on players, it shows that for every player in that list there is 'name' of the player and there is the 'key_name' of the team available too. So how can I do the below ?? players = Player.all().fetch(1000) # This is 1 DB read for player in players: # This will iterate 1000 times self.response.out.write(player.name) # This is obviously not a DB read self.response.out.write(team_list[player.<SOME WAY OF GETTING TEAM KEY NAME>]) # Here 'team_list' already has (key_name, name) for all 5 teams I have been struggling with this for a long time. Have read every available documentation. I could just hug the person that can help me here :-) Disclaimer: The above problem description is not a real scenario. It is a simplified arrangement that represents my problem exactly. I have run into it in a rater complex and big GAE appication.

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  • What makes deployment successful for some users and unsuccessful for others?

    - by Julien
    I am trying to deploy a Visual C++ application (developed with Microsoft Visual Studio 2008) using a Setup and Deployment Project. After installation, users on some target computers get the following error message after launching the application executable: “This application has failed to start because the application configuration is incorrect. Reinstalling the application may fix the problem.” Another user after installation could run the application properly. I cannot find the root cause of this problem, despite spending several hours on the Visual Studio help files and online forums (most postings date back to 2006). Does anyone at Stack Overflow have a suggestion? Thanks in advance. Additional details appear below. The application uses FLTK 1.1.9 for a GUI library, as well as some Boost 1.39 libraries (regex, lexical_cast, date_time, math). I made sure I am trying to deploy the release version (not the debug version) of the application. The Runtime library in the Code Generation settings is Multi-threaded DLL (/MD). The dependency walker of myapp.exe lists the following DLLs: wsock32.dll, comctl32.dll, kernel32.dll, user32.dll, gdi32.dll, shell32.dll, ole32.dll, mvcp90.dll, msvcr90.dll. In the Setup and Deployment Project, I add the following DLLs to the File System on Target Machine: fltkdlld.dll, and a folder named Microsoft.VC90.CRT with msvcm90.dll, msvcp90.dll, mcvcr90.dll and Microsoft.VC90.CRT.manifest. The installation process on the target computers getting the error message requires having the .Net Framework 3.5 installed first. Any suggestion? Thanks in advance!

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  • Permission denied to access property 'toString'

    - by Anders
    I'm trying to find a generic way of getting the name of Constructors. My goal is to create a Convention over configuration framework for KnockoutJS My idea is to iterate over all objects in the window and when I find the contructor i'm looking for then I can use the index to get the name of the contructor The code sofar (function() { constructors = {}; window.findConstructorName = function(instance) { var constructor = instance.constructor; var name = constructors[constructor]; if(name !== undefined) { return name; } var traversed = []; var nestedFind = function(root) { if(typeof root == "function" || traversed[root]) { return } traversed[root] = true; for(var index in root) { if(root[index] == constructor) { return index; } var found = nestedFind(root[index]); if(found !== undefined) { return found; } } } name = nestedFind(window); constructors[constructor] = name; return name; } })(); var MyApp = {}; MyApp.Foo = function() { }; var instance = new MyApp.Foo(); console.log(findConstructorName(instance)); The problem is that I get a Permission denied to access property 'toString' Exception, and i cant even try catch so see which object is causing the problem Fiddle http://jsfiddle.net/4ZwaV/

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  • JoinColumn name not used in sql

    - by Vladimir
    Hi! I have a problem with mapping many-to-one relationship without exact foreign key constraint set in database. I use OpenJPA implementation with MySql database, but the problem is with generated sql scripts for insert and select statements. I have LegalEntity table which contains RootId column (among others). I also have Address table which has LegalEntityId column which is not nullable, and which should contain values referencing LegalEntity's "RootId" column, but without any database constraint (foreign key) set. Address entity is mapped: @Entity @Table(name="address") public class Address implements Serializable { ... @ManyToOne(fetch=FetchType.LAZY, optional=false) @JoinColumn(referencedColumnName="RootId", name="LegalEntityId", nullable=false, insertable=true, updatable=true, table="LegalEntity") public LegalEntity getLegalEntity() { return this.legalEntity; } } SELECT statement (when fetching LegalEntity's addresses) and INSERT statment are generated: SELECT t0.Id, .., t0.LEGALENTITY_ID FROM address t0 WHERE t0.LEGALENTITY_ID = ? ORDER BY t0.Id DESC [params=(int) 2] INSERT INTO address (..., LEGALENTITY_ID) VALUES (..., ?) [params=..., (int) 2] If I omit table attribute from mentioned statements are generated: SELECT t0.Id, ... FROM address t0 INNER JOIN legalentity t1 ON t0.LegalEntityId = t1.RootId WHERE t1.Id = ? ORDER BY t0.Id DESC [params=(int) 2] INSERT INTO address (...) VALUES (...) [params=...] So, LegalEntityId is not included in any of the statements. Is it possible to have relationship based on such referencing (to column other than primary key, without foreign key in database)? Is there something else missing? Thanks in advance.

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