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• Do Managers in Python Multiprocessing module lock the shared data?

  - by AnonProcess

  This Question has been asked before: http://stackoverflow.com/questions/2936626/how-to-share-a-dictionary-between-multiple-processes-in-python-without-locking However I have several doubts regarding the program given in the answer: The issue is that the following step isn't atomic d['blah'] += 1 Even with locking the answer provided in that question would lead to random results. Since Process 1 read value of d['blah'] saves it on the stack increments it and again writes it. In Between a Process 2 can read the d['blah'] as well. Locking means that while d['blah'] is being written or read no other process can access it. Can someone clarify my doubts?

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• Jquery counting elements by class what is the best way to implement this?

  - by 133794m3r

  Ok what i'm trying to do is to count all of the elements in the current page with the same class and then i'm going to use it to be added onto a name for a input form. Basically i'm allowing users to click on an and then by doing so add another one for more of the same type of items. But i can't think of a way to count all of these simply with jquery/javascript. I was going to then name the item as something like name="whatever(total+1)", if anyone has a simple way to do this i'd be extremely grateful as javascript isn't exactly my native tongue and stack overflow usually has a ton of great answers and a great community so i'm hoping my query will not go unheard.

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• Implementing a 'many-to-many' database

  - by Raven Dreamer

  Greetings, stack*overflow* In my database, I already have one table, 'contacts' that contains records of individual people. I also have several other tables in my database which represent "skill sets" that contain records denoting a particular skill. 1) Am I correct in plotting this as a "many-to-many" relationship? (each contact can have multiple skill sets, and each skill set can belong to multiple contacts) 2) I'm new to databases -- do I want to link the tables? 3) Is there a way to implement this in my program (C# + windows forms) such that for any given record in the 'contacts' table, either the names of all associated 'skill set' tables or all the 'skill' records associated with the 'contact' record could be retrieved? (Database is located on SQL Server Express 2008)

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• Does writing program using global variables is safer?

  - by ZoZo123

  I was reading about buffer, stack and heap overflows. I read this post as well. my question is like that: if I use only global variables in my code, can I say it prevents all the exploits of overflow? let's say I have this buffers in code declared in the global scope: char buf1[10]; char buf2[100]; If I send buf1 as the buffer to recv(int s, char *buf, int len,int flags); I will overwrite the data segment and may ruin the buf2 content, right? Would I be able to run a code from it because as I know it is not a code segment and data segment is not executable. Can we conclude that using Globals is the safest way?

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• Should I make my MutexLock volatile?

  - by sje397

  I have some code in a function that goes something like this: void foo() { { // scope the locker MutexLocker locker(&mutex); // do some stuff.. } bar(); } The function call bar() also locks the mutex. I am having an issue whereby the program crashes (for someone else, who has not as yet provided a stack trace or more details) unless the mutex lock inside bar is disabled. Is it possible that some optimization is messing around with the way I have scoped the locker instance, and if so, would making it volatile fix it? Is that a bad idea? Thanks.

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• Does a rollback still occur if I use begin...rescue and an error occurs?

  - by codeman73

  I've got some strange errors happening in my rails app and I'm trying to log better errors instead of the whole stack of passenger stuff that I don't care about. I thought I would do this with a Rescue clause and explicit error handling, like logging the params hash. But I'm concerned if this would interrupt any rollback that is happening. For that matter, I'm assuming rollbacks automatically occur when an error occurs as part of the normal rails error handling, but I haven't been able to find that documented anywhere. I'm using Dreamhost with MySQL, so I thought transactions and rollbacks were happening there.

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• is it possible to use a python scrapper in a website?

  - by Tom

  I want to scrap a website and use that content in a website of my own. I am just wondering if that can be done with python 2.7, and if so how? If not, do I have to use JavaScript to scrap it? And do you have a good place to learn how to do that or good libraries for it. For those of you wondering, the website I am scrapping is legal, and they allow for this to be done. I have searched all over but apparently nobody tries to implement these scrappers that they write. I can write a web scrapper in python just fine. Say my scrapper scraps a name from a wikipedia page (John Doe for example), how can I use that name that I get in my website? Another update, I have found pjsrape and PhantomJS. I have only found one stack overflow post and the github examples with aren't very intuitive. If anybody has any experience or better ways to do it I would very much appreciate it

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• Which is the best Linux C/C++ debugger (or front-end to gdb) to help teaching programming?

  - by omer.gimenez

  I teach a sort of "lite" C++ programming course to novices ("lite" meaning no pointers, no classes, just plain old C, plus references and STL string and vectors). Students have no previous experience in programming, so I believe that using an interactive debugger would help them understand program flow, variables, and recursion. The course is taught in Linux. Teaching them to use gdb is just overkill (they will not use nor understand most features). I just need something simple but easy to use: to see at which line the program is now, what is in the stack (local variables, previous calls, etc.). I look something similar to old Turbo Pascal or Turbo C++ Borland's debugger, or Visual Studio debugger. Thank you,

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• Algorithm Question.. Linked List..

  - by AGeek

  Hi, Scenario is as follows:- I want to reverse the direction of the singly linked list, In other words, after the reversal all pointers should now point backwards.. Well the algorithm should take linear time. The solution that i have thought of using another datastructure A Stack.. With the help of which the singly linked list would be easily reversed, with all pointers pointing backwards.. But i am in doubt, that whether the following implementation yeild linear time complexity.. Please comment on this.. And if any other efficient algorithm is in place, then please discuss.. Thanks.

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• Reusing a vector in C++

  - by Bobby

  I have a vector declared as a global variable that I need to be able to reuse. For example, I am reading multiple files of data, parsing the data to create objects that are then stored in a vector. vector<Object> objVector(100); void main() { while(THERE_ARE_MORE_FILES_TO_READ) { // Pseudocode ReadFile(); ParseFileIntoVector(); ProcessObjectsInVector(); /* Here I want to 'reset' the vector to 100 empty objects again */ } } Can I reset the vector to be "vector objVector(100)" since it was initially allocated on the stack? If I do "objVector.clear()", it removes all 100 objects and I would have a vector with a size of 0. I need it to be a size of 100 at the start of every loop.

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• How can I take eclipse out of MDI mode?

  - by user51189

  Does anyone know of a way to make Eclipse an SDI application rather than an MDI one? SDI - Single document interface, each pane is its own window MDI - Multiple document interface, all of the panes are stuck inside one "master" window. Eclipse is an MDI application. All of the little panes (like the call stack, variable viewer, ect) are part of the one master Eclipse window. Rather than having all of the windows stuck inside one master "eclipse" window, I'd like them to all be their own free-floating windows.

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• cross domain DOM access and manipulation in Java ?

  - by gaqer

  In my Java app, how can I incorporate the browser (which loads and renders URLs) in Swing and access it's DOM and manipulate HTML ? How can you embed such browser in a Rich Internet Application and access it's DOM ? More specifically, Vaadin ? Is there a HTTP proxy class that can load an external URL, and render it to the user ? This was what I was doing on LAMP stack....but I want to switch to Vaadin or some Java web framework where I can just use Java to do everything from server-side to client-side logic design, so I can focus more on application logic. (aka looking for developer friendly frameworks like Vaadin). Thank you and have a great weekend !

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• I have a ConnectException that isn't being caught for some reason

  - by aakbari1024

  I'm working on an Android application that uses sockets. I have a function called initializeStreams() which opens the socket and attempts a connection. This function throws a ConnectException if the connection could not be established. But for some reason, in the code that calls initializeStreams(), which has a catch block for ConnectException, the log prints out its own stack trace for the exception instead of going to the catch block. The catch block is never reached at all, even though the exact exception is being thrown. Here's the code: The try block: try { initializeStreams(); /* drivesList = new ArrayList<String>(); drivesList = enumerateDrives();*/ } catch (ConnectException e) { //Log.i(TAG, "caught connect exception"); /*loadingProgress.dismiss(); retryConnection();*/ } initializeStreams(): public void initializeStreams() throws ConnectException { try { Log.i(TAG, "Attempting to connect"); requestSocket = new Socket(SERVER_ADDR, PORT); /* other code */ } catch (IOException e) { e.printStackTrace(); } I can't figure this out, so any help would be much appreciated. }

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• PHP reporting error. DB verify how to?

  - by iamfab

  Error reporting Notice: Undefined variable: random_chars in wamp\www\php_sandbox\idgen.php on line 21 Call Stack: # Time Memory Function Location 1 0.0045 678928 {main}( ) ..\idgen.php:0 GPB7446 How do I fix this error? Using this code like an automatic unique id generator. How do I connect to DB to verify code is truly unique before allowing it to be assigned to a user creating a new account? Thanks <?php $characters = array( "A","B","E","F","G","H","J","K","M","N","P","R","S","T","W","X","Y","Z"); $keys = array(); while(count($keys) < 3) { $x = mt_rand(0, count($characters)-1); if(!in_array($x, $keys)) { $keys[] = $x; } } foreach($keys as $key){ $random_chars .= $characters[$key];} $randNum = rand(2327,9987); $randLet = rand(2327,9987); echo $random_chars . $randNum; ?>

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• rake db:migrate and rake db:create both work on test database, not development database

  - by geography_guy

  I am new to Stack Overflow and Ruby on Rails. My problem is, when I run the command rake db:create or rake db:migrate, the test database is affected, but the development database is not. rails (3.2.2) my database.yml: # Warning: The database defined as "test" will be erased and # re-generated from your development database when you run "rake". # Do not set this db to the same as development or production. test: &test adapter: postgresql encoding: unicode database: ticketee_test pool: 5 username: ticketee password: my_password_here development: adapter: postgresql encoding: unicode database: ticketee_development pool: 5 username: ticketee password: my_password_here production: adapter: postgresql encoding: unicode database: ticketee_production pool: 5 username: ticketee password: my_password_here cucumber: <<: *test

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• How to rate a connect four game situation in java

  - by MrPink

  Hey, I am trying to write a simple AI for a "Get four" game. The basic game principles are done, so I can throw in coins of different color, and they stack on each other and fill a 2D Array and so on and so forth. until now this is what the method looks like: public int insert(int x, int color) //0 = empty, 1=player1 2=player2" X is the horizontal coordinate, as the y coordinate is determined by how many stones are in the array already, I think the idea is obvious. Now the problem is I have to rate specific game situations, so find how many new pairs, triplets and possible 4 in a row I can get in a specific situation to then give each situation a specific value. With these values I can setup a "Game tree" to then decide which move would be best next (later on implementing Alpha-Beta-Pruning). My current problem is that I can't think of an efficient way to implement a rating of the current game situation in a java method. Any ideas would be greatly appreciated! greetings from Germany Mr. Pink

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• Passing input to Ant's <exec> task

  - by mikek

  I have an Ant script running a standard -task after taking in an inputed password: <input message="Password:" addproperty="password"> <handler classname="org.apache.tools.ant.input.SecureInputHandler" /> </input> <exec executable="/bin/sh" input="${password}" failonerror="true"> <arg line='-c "myScript.sh"' /> </exec> The script myScript.sh prompts the user for a password, and, it was my understanding that from the Ant documentation that input is supposed relay input into whatever the <exec> task is executing, but instead I get (for entering the password foobar) [exec] Failed to open /usr/local/foobar which is followed by a stack trace from my script complaining about an incorrect password...so obviously I've understood the documentation wrong. Does anybody know how to handle prompted input from external scripts in Ant?

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• Documentation for Qt documentation comments? Qt + Doxygen?

  - by Jake Petroules

  Where can I find documentation for Qt documentation comments? I'm referring to how Qt uses a specific style for documentation comments, like so: /*! \class MyClassName \brief The MyClassName class is used as an example on Stack Overflow. This class serves a few functions, the most important being: \list \i So people can understand my question. \i So people can have a few laughs at the comedy in my example. \endlist */ ...you get the picture. So where can I find information about all the switches, like \class, \list, \brief, etc. Also, what tool(s) do I use to generate documentation files from these comments in my source files? Does Doxygen support this syntax?

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• Force an object to be allocated on the heap

  - by Warren Seine

  A C++ class I'm writing uses shared_from_this() to return a valid boost::shared_ptr<>. Besides, I don't want to manage memory for this kind of object. At the moment, I'm not restricting the way the user allocates the object, which causes an error if shared_from_this() is called on a stack-allocated object. I'd like to force the object to be allocated with new and managed by a smart pointer, no matter how the user declares it. I thought it could be done through a proxy or an overloaded new operator, but I can't find a proper way of doing that. Is there a common design pattern for such usage? If it's not possible, how can I test it at compile time?

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• Web app implementation question.

  - by John Berryman

  I would like to create a web app similar to Stack Overflow in that the users will have different "point" levels and that their capabilities within the web app will be different based upon their point level. Question: How can this best be implemented? How can it be implemented in a way that is un-hackable (i.e. accessing capabilities that should not be available)? I figure there are two ways to do this: server-side and client-side. For the server-side solution, for each page request you check who the user is and have the CGI rewrite the page so that the client only gets a web page with the intended capabilities. For the client-side solution, the server gives the client the fully capable app and it is the client's job to check the point level and to handicap the app appropriately. It seems like the client-side solution would be easier on the server, (which is really important for my app), but more susceptible to someone hacking and using capabilities unwarranted by their point level.

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• iPhone, how to dyanmic create new entity (table) via core data model?

  - by Robin

  as topic, I just want create new Entity(table) in sqlite , my code as follows: +(BOOL)CreateDataSet:(NSManagedObjectModel *) model attributes:(NSDictionary*)attributes entityName:(NSString*) entityName { NSEntityDescription *entityDef = [[NSEntityDescription alloc] init]; [entityDef setName:entityName]; [entityDef setManagedObjectClassName:entityName]; [model setEntities:[NSArray arrayWithObject:entityDef]]; //@step NSArray *properties = [CoreDataHelper CreateAttributes:attributes]; [entityDef setProperties:properties]; [entityDef release]; return TRUE; } but it throw errors: Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Can't modify an immutable model.' * Call stack at first throw: ( 0 CoreFoundation 0x01c5abe9 __exceptionPreprocess + 185 1 libobjc.A.dylib 0x01daf5c2 objc_exception_throw + 47 2 CoreData 0x0152634a -[NSManagedObjectModel(_NSInternalMethods) _throwIfNotEditable] + 106 3 CoreData 0x01526904 -[NSManagedObjectModel setEntities:] + 36 .... that seem show the model is read only..... anyone can help on this problem? thanks

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• paging php error - undefined index

  - by fusion

  i've a search form with paging. when the user enters the keyword initially, it works fine and displays the required output; however, it also shows this error: Notice: Undefined index: page in C:\Users\user\Documents\Projects\Pro\search.php on line 21 Call Stack: 0.0011 372344 1. {main}() C:\Users\user\Documents\Projects\Pro\search.php:0 . .and if the user clicks on the 'next' page, it shows no output with this error thrown: Notice: Undefined index: q in C:\Users\user\Documents\Projects\Pro\search.php on line 19 Call Stack: 0.0016 372048 1. {main}() C:\Users\user\Documents\Projects\Pro\search.php:0 this is my code: <?php ini_set('display_errors',1); error_reporting(E_ALL|E_STRICT); include 'config.php'; $search_result = ""; $search_result = trim($_GET["q"]); $page= $_GET["page"]; //Get the page number to show if($page == "") $page=1; $search_result = mysql_real_escape_string($search_result); //Check if the string is empty if ($search_result == "") { echo "<p class='error'>Search Error. Please Enter Your Search Query.</p>" ; exit(); } if ($search_result == "%" || $search_result == "_" || $search_result == "+" ) { echo "<p class='error1'>Search Error. Please Enter a Valid Search Query.</p>" ; exit(); } if(!empty($search_result)) { // the table to search $table = "thquotes"; // explode search words into an array $arraySearch = explode(" ", $search_result); // table fields to search $arrayFields = array(0 => "cQuotes"); $countSearch = count($arraySearch); $a = 0; $b = 0; $query = "SELECT cQuotes, vAuthor, cArabic, vReference FROM ".$table." WHERE ("; $countFields = count($arrayFields); while ($a < $countFields) { while ($b < $countSearch) { $query = $query."$arrayFields[$a] LIKE '%$arraySearch[$b]%'"; $b++; if ($b < $countSearch) { $query = $query." AND "; } } $b = 0; $a++; if ($a < $countFields) { $query = $query.") OR ("; } } $query = $query.")"; $result = mysql_query($query, $conn) or die ('Error: '.mysql_error()); $totalrows = mysql_num_rows($result); if($totalrows < 1) { echo '<span class="error2">No matches found for "'.$search_result.'"</span>'; } else { $limit = 3; //Number of results per page $numpages=ceil($totalrows/$limit); $query = $query." ORDER BY idQuotes LIMIT " . ($page-1)*$limit . ",$limit"; $result = mysql_query($query, $conn) or die('Error:' .mysql_error()); ?> <div class="caption">Search Results</div> <div class="center_div"> <table> <?php while ($row= mysql_fetch_array($result, MYSQL_ASSOC)) { $cQuote = highlightWords(htmlspecialchars($row['cQuotes']), $search_result); ?> <tr> <td style="text-align:right; font-size:15px;"><?php h($row['cArabic']); ?></td> <td style="font-size:16px;"><?php echo $cQuote; ?></td> <td style="font-size:12px;"><?php h($row['vAuthor']); ?></td> <td style="font-size:12px; font-style:italic; text-align:right;"><?php h($row['vReference']); ?></td> </tr> <?php } ?> </table> </div> <?php //Create and print the Navigation bar $nav=""; if($page > 1) { $nav .= "<a href=\"search.php?page=" . ($page-1) . "&string=" .urlencode($search_result) . "\"><< Prev</a>"; } for($i = 1 ; $i <= $numpages ; $i++) { if($i == $page) { $nav .= "<B>$i</B>"; }else{ $nav .= "<a href=\"search.php?page=" . $i . "&string=" .urlencode($search_result) . "\">$i</a>"; } } if($page < $numpages) { $nav .= "<a href=\"search.php?page=" . ($page+1) . "&searchstring=" .urlencode($search_result) . "\">Next >></a>"; } echo "<br /><br />" . $nav; } } else { exit(); } ?>

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• Package names - impl v internal

  - by Ben J

  In my time of digging around Java APIs I have come across both impl and internal packages. Up until now I never really thought about the difference - as with all enterprisey Java apps, I figured they just meant that "actual implementation in here; you (API user) should be really using the interface. Go away." A little bit of digging around Stack Overflow seems to suggest that the internal package at least can have some security placed around it. So, what is the difference? I don't think it is a matter of taste because I have seen APIs with both.

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• Global Exception Handlers in Java

  - by Samuh

  I am thinking of setting up a global, default Exception handler for my (Android) Mobile application(which uses Java syntax) using Thread.setDefaultUncaughtExceptionHandler(...) call. I am thinking of just displaying an Alert Dialog with appropriate message to the user. Are there any gotchas, caveats and rules that one needs to follow when setting DefaultExceptionHandlers? Any best practices like making sure that the process is killed, full stack trace is written to logs etc. ? Links to documentation, tutorials etc. that can throw some light on this are welcome. Thanks.

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• navigationproblem

  - by sudhakarilla

  I have problem .. i get debugerror i will used in json Category *selectcategory = [[data categorys]objectAtindex:indexPath.row]; productlistviewcontroller *plviewcontroller = [[productlistviewcontroller alloc]initwithNibName:@"productlistviewcontroller" bundle:nil]; plviewcontroller.category = selectedcategory; [self.navigationcontroller pushviewcontroller:plviewcontroller animated:YES]; please check the my program. it doesnot goto nextviewcontroller. console error is 2009-02-13 18:32:17.405 xxxxxxxx[1491:20b] * -[NsDecimalNumber length]: unrecognized selector sent to instance 0xc3f10ff0 2009-02-13 18:32:17.406 xxxxxxxx[1491:20b] Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '** -[NsDecimalNumber length ]: unrecognized selector sent to instance 0xc3f10ff0' 2009-02-13 18:32:17.406 xxxxxxxx[1491:20b] Stack: ( 2417225995, 2527100475, 2417255178, 2417248524, 2417248722, 22199, 9853, 816111650, 816149355, 2458333742, 2416728869, 2416729304, 827745792, 827745989, 816114848, 816160924, 9628, 9482 ) please send soluation...

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