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• Is there any reason why someone would want to create an Core Data model programmatically?

  - by mystify

  I wonder in which cases it would be good to make an NSManagedObjectModel completely programmatically, with NSEntityDescription instances and all this stuff. I'm that kind of person who prefers to code programmatically, rejecting Interface Builder. But when it comes to Core Data, I have a hard time figuring out why I should kill my time NOT using the nice Xcode Data Modeler tool. And since data models are stuck to a given state (except when you want to do some ugly migration operations where thinks probably go wrong and users get mad, really mad), I see no big sense in a data model that's made programmatically for the purpose of changing it all the time. Did I miss something?

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• How to use a object whose copy constructor and copy assignment is private?

  - by coanor

  In reading TCPL, I got a problem, as the title refered, and then 'private' class is: class Unique_handle { private: Unique_handle& operator=(const Unique_handle &rhs); Unique_handle(const Unique_handle &rhs); public: //... }; the using code is: struct Y { //... Unique_handle obj; }; and I want to execute such operations: int main() { Y y1; Y y2 = y1; } although, these code are come from TCPL, but I still can not got the solution... Can anybody help me, appreciate.

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• Switch to BigInteger if necessary

  - by fahdshariff

  I am reading a text file which contains numbers in the range [1, 10^100]. I am then performing a sequence of arithmetic operations on each number. I would like to use a BigInteger only if the number is out of the int/long range. One approach would be to count how many digits there are in the string and switch to BigInteger if there are too many. Otherwise I'd just use primitive arithmetic as it is faster. Is there a better way? Is there any reason why Java could not do this automatically i.e. switch to BigInteger if an int was too small? This way we would not have to worry about overflows.

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• Help me understand Dispose() implementation code from MSDN

  - by Benny

  the following code is from MSDN: Idisposable pattern protected virtual void Dispose(bool disposing) { // If you need thread safety, use a lock around these // operations, as well as in your methods that use the resource. if (!_disposed) { if (disposing) { if (_resource != null) _resource.Dispose(); Console.WriteLine("Object disposed."); } // Indicate that the instance has been disposed. _resource = null; _disposed = true; } } why the following statement: _resource = null; _disposed = true; are not enclosed by if (disposing) statement block? for me i would probably write like this: if (disposing) { if (_resource != null) { _resource.Dispose(); _resource = null; _disposed = true; } Console.WriteLine("Object disposed."); } anything wrong with my version?

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

  - by tomp

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

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• Storing And Using Microsoft User Account Credentials in SQL Server 2008 database

  - by user337501

  I'm not exactly positive how to word this for the sake of the title so please forgive me. Also I can't seem to figure out how to even google this question, so I'm hoping that I can get a lead in the right direction. Part of my software(VB.NET App) requires the ability to access/read/write a shared network folder. I have an option for the user to specify any credentials that might be needed to access said folder. I want to store these credentials given in the SQL Server database as part of the config (I have a table which contains configuration). My concern is that the password for the user account will be unencrpyted. Yet, if I encrypt the password the VB.NET App And/Or database will be unable to use the credentials for file i/o operations unless the Password is unencrypted before use. I'm fishing for suggestions on how to better handle this situation.

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• How do I redirect to the current page in Servlet Filter?

  - by JeffJak

  I have a page say: /myapp/test.jsp?queryString=Y. The filter needs to redirect to current page. It should go to /myapp/test.jsp (without the query string). The below seems to bring it to to the context root: /myapp. I am running in WAS6.1. public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException { HttpServletRequest httpReq = (HttpServletRequest) req; HttpServletResponse httpResp = (HttpServletResponse) resp; { boolean blnNeedToRedirect = true; if (blnNeedToRedirect) { httpResp.sendRedirect("."); return; } chain.doFilter(req, resp); }

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• Making self-logging modules with Log::Log4perl

  - by Oesor

  Is there a way to use Log::Log4perl to make a smart self-logging module that logs its operations to a file even in the absence of the calling script not initializing Log4perl? As far as I can tell from the documentation, the only way to use Log4perl is to initialize it in the running script from a configuration, then modules implementing Log4perl calls log themselves based on the caller's Log4perl config. Instead, I'd like the modules to provide a default initialization config for Log4perl. This would provide the default file appender for the module's category. Then, I could override this behavior by initing Log4perl in the caller with a different config if needed, and everything would hopefully just work. Is this sort of defensive logging behavior possible or am I going to need to rely on initing Log4perl in every .pl script that calls the module I want logged?

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• Actionscript 3.0 Play and pause add effect.

  - by Jordan Pagaduan

  layer 1 -- an embeded video layer 2 -- an invisible button **Here is my code in layer 3** stop(); var vid:Boolean = true; function vid_event(event:MouseEvent) { if (vid) { stop(); event.target.gotoAndStop('pause'); vid = false; } else { play(); event.target.gotoAndStop('play'); vid = true; } } vid_btn.addEventListener(MouseEvent.CLICK,vid_event); I already get the play and pause fuction (that's all i need). I just want to add an image to show when the video still not playing in and pause. If the video played the image will disappear and if pause the image will appear. Thank You

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• ContextSwitchDeadlock Was Detected error in C#

  - by assassin

  Hi, I am running a C# application, and during run-time I get the following error: The CLR has been unable to transition from COM context 0x20e480 to COM context 0x20e5f0 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations. Can anyone please help me out with the problem here? Thanks a lot.

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• Conditionally required jsf validation in a4j form

  - by volothamp

  Hello, I'm having a little problem with using conditionally evaluated expression in jsf/a4j Here's my code <a4j:form> <h:inputText id="id1" value="#{mybean.myvalue}" size="1" required="#{not mybean.condition}" rendered="#{not mybean.condition}" requiredMessage="Put a number in here" /> <h:selectBooleanCheckbox value="#{mybean.condition}"> <a4j:support event="onclick" reRender="id1"/> </h:selectBooleanCheckbox> <a4j:commandButton action="#{mybean.myaction}" value="Do something" /> </a4j:form> The boolean checkbox conditionally enable/disable the validation. This doesn't work: the a4j:commandButton simply skip the validation. Thanks.

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• RESTful application validation. Mix of frontend/backend validation. How?

  - by Julian Davchev

  Hi. Using RESTful for all backend persistance and operations. I just pass data from frontend (by frontend I don't mean clientside but the part that is making use of the REST) to rest and data gets back success or no with validation errors if any. Thing is I have stuff that should be validated on frontend too..like csrf tokens, captcha etc. Only reasonable way is I mix validation coming from token/captcha checks and validation errors coming back from REST. Issue with this will be kinda automation as I wouldn't want form field names to map 1:1 with backend field names use by the REST documents. Any pointers ideas are more than welcome.

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• How to implement Voting for Grails Domain Classes?

  - by userWebMobile

  I have a Book class and need to implement a yes/no voting functionality. My domain classes look like this: class Book { String title static hasMany = [votes: Vote] } class User { String name static hasMany = [votes: Vote] } class Vote { boolean yesVote static belongsTo = [user: User, book: Book] } What is the best way to implement a voting for the book class. I need the following informations: What is the average yesVote for a book over all votes (either yes or no)? How to check if a specific user has done a vote? What is the best way to implement the computation of the average yesVote such that the performance does not drop?

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• Android internet connectivity check problem

  - by Chaoz

  Hello, I'm new to Android development and working on an Android application that requires the phone to be connected to the internet, through either Wifi, EDGE or 3G. This is the code that I'm using: public static boolean isConnected() { ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); return cm.getActiveNetworkInfo().isConnectedOrConnecting(); } I've also set these permissions in the manifest file: <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> This works fine in the emulator running version 1.5 of Android when 3G is enabled, but it crashes when I disable the 3G connection. My application throws a null pointer exception when I call isConnectedOrConnecting(). Hope that anyone knows the solution to this. Thanks in advance!

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• Empty Structures compile in VB 10+

  - by Mark Hurd

  This is at least a documentation error, if not a bug. In VB.NET prior to .NET 4.0 (i.e. VB.NET 7 through 9) an empty Structure declaration fails at compile-time with error BC30281: Structure 'MySimpleEmpty' must contain at least one instance member variable or Event declaration. E.g. The following two structures compile successfully in VB10, and not prior: Structure MySimpleEmpty End Structure Public Structure AnotherEmpty Public Const StillEmpty As Boolean = True End Structure I note the documentation for the Error BC30281 stops at VB9, but the documentation for the Structure statement still has the datamemberdeclarations as required even as of VB11 (.NET 4.5 VS2012). These two Structures compile in VB11 (VS2012) as well. (Thanks John Woo.) Is there some blog entry or documentation confirming this is an intended change or a bug in VB10 and later?

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• Boost Filesystem Library Visual C++ Compile Error

  - by John Miller

  I'm having the following issue just trying to compile/run some of the example programs with the Boost Filesystem Library. I'm using MS-Visual C++ with Visual Studio .NET (2003). I've installed the Boost libraries, version 1.38 and 1.39 (just in case there was a version problem) using the BoostPro installers. If I just try to include /boost/filesystem/operations.hpp I receive the following error: \boost_1_38\boost\system\error_code.hpp(230) : error C2039: 'type' : is not a member of 'boost::enable_if<boost::system::is_error_condition_enum<Cond,boost::detail::enable_if_default_T>' Any help is greatly appreciated. Thank you!

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• Hebbian learning

  - by Bane

  I have asked another question on Hebbian learning before, and I guess I got a good answer which I accepted, but, the problem is that I now realize that I've mistaken about Hebbian learning completely, and that I'm a bit confused. So, could you please explain how it can be useful, and what for? Because the way Wikipedia and some other pages describe it - it doesn't make sense! Why would we want to keep increasing the weight between the input and the output neuron if the fire together? What kind of problems can it be used to solve, because when I simulate it in my head, it certainly can't do the basic AND, OR, and other operations (say you initialize the weights at zero, the output neurons never fire, and the weights are never increased!)

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• How to limit data to users who own it without limiting admin users in CakePHP?

  - by cdburgess

  Currently I am writing an application where I have multiple users. They have data that should only be visible to them and not the other authenticated users in the system. I also have administrators who manage the system and have access to all of the information. What is the best way to limit users to their data without limiting admin users? Currently I am using a callback to limit the queries by user, but the admin will get the same limits. So I need to know a better way to do it. More importantly, the right way to do it. For example, I want the standard user to be able to see their user information only and be limited to CRUD operations on their information only. The admin, however, should be able to see ALL users and CRUD ALL user data. Any ideas?

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• linq and contains

  - by kusanagi

  i have func public PageOfList<ConsaltQuestion> Filter(int? type, int pageId, EntityCollection<ConsaltCost> ConsaltRoles) { // return _dataContext.ConsaltQuestion.Where((o => o.Type == type || type == null) && (o=>o.Paid == paid)); return (from i in _dataContext.ConsaltQuestion where ((i.Type == type || type == null) && (i.Paid == true) && (ConsaltRoles.Contains(ConsaltCostDetails(i.Type.Value)))) select i).ToList().ToPageOfList(pageId, 20); } it return error LINQ to Entities does not recognize the method 'Boolean Contains(mrhome.Models.ConsaltCost)' method, and this method cannot be translated into a store expression. how can i fix it?

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• Get DataGridView checkbox cell value?

  - by George

  Hello guys. I'm having a strange issue here. I have a 3 column datagrid that is filled by a connection with the database. So far so good. I have an extra column, of checkbox type. I need to get it's value for perfoming a bulk operation on it. Here is the catch: When all cells are selected, it works fine. But when an user selects any cell that its not the first, software gives me a object reference exception. Here is the code public List<String> GetSelected() { List<String> selected = new List<String>(); foreach(DataGridViewRow row in datagrid.rows) { if ((Boolean)row.Cells[wantedCell].Value == true) { selected.Add(row.Cells[anotherCell]); } } } I tracked down the failure to the if-test, throwing a exception, because the value of the cell is read as null. Any thougths? Thanks

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• DDEX Firebird editing queries duplicates columns in Visual Studio 2008

  - by A Bothe

  Hello everybody! I don't know if some of you also has experienced it but when I edit a query in Visual Studio (it uses DDEX 2.0.5 for accessing the Firebird 2.5 database), it duplicates some of the columns. What's really interesting is the fact that only System.Boolean columns are duplicated: Originally, there was only ,for instance, a 'PRO_DELETED' field... Now I wanted to sort my results by this field - I had to change the select statement in the so-called QueryBuilder by adding "ORDER BY PRO_DELETED" ...After clicking OK it somehow created a new column (!?) called 'PRO_DELETED1' My question is: Why does DDEX add such a new row to the column view and why can't I access the original PRO_DELETED field anymore? Thanks in advance!

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• Which database engines support IP addresses as a native type?

  - by Matt McClellan

  I'm trying to find databases with support for IP addresses as a native type (as opposed to storing as a string, or an unsigned integer, which at least one commenter has already pointed out won't work for IPv6). The primary reason I'm looking for this is ease of development. For example, sorting on a "native" IP address column would be correct (as opposed to when it's stored as a string). I would assume support for such a type would also include useful operations such as determining if an IP address is inside a specified network for use in WHERE clauses. The only one I'm aware of so far is PostgreSQL with its inet class. Does anyone have any others?

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• Communication via internet in Java

  - by Stuart

  What I mean is like servers on video games. You can run an application and it will set up a server on your computer with an IP and a port. For example, how would you make an application where one host application sets up a thing where it has an IP and a port, and another computer that has access to the internet as well can type in the IP and port and it would be able to communicate with the host? I mean simple communication, like sending a boolean or String. And would there be any security problems that would be needed to fix?

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• Rewrite this function as DB query?

  - by aLk

  I'm cleaning up my code, should i change the following function to a MySQL query? If so what would be a nice MySQL function to achieve this functionality? public ArrayList getNewTitles(ArrayList candidateTitles, ArrayList existingTitles) { ArrayList newTitles = new ArrayList(); Movie movie = new Movie(); boolean isNew = true; for(int i=0; i<candidateTitles.size(); i++) { for(int j=0; j<existingTitles.size(); j++) { movie = (Movie)existingTitles.get(j); if(((String)candidateTitles.get(i)).equals(movie.getRawTitle())) { isNew = false; } } if(isNew == true) { System.out.println("newTitle for crawling: " + (String)candidateTitles.get(i)); newTitles.add((String)candidateTitles.get(i)); } else { System.out.println("candidate binned: " + (String)candidateTitles.get(i)); } isNew = true; } return newTitles; }

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• Anonymous code blocks in Groovy

  - by piepera

  Is there a way to use anonymous code blocks in Groovy? For example, I'm trying to translate the following Java code into Groovy: { int i = 0; System.out.println(i); } int i = 10; System.out.println(i); The closest translation I can come up with is the following: boolean groovyIsLame = true; if (groovyIsLame) { int i = 0; System.out.println(i); } int i = 10; System.out.println(i); I know anonymous code blocks are often kind of an antipattern. But having variables with names like "inputStream0" and "inputStream1" is an antipattern too, so for this code I'm working on, anonymous code blocks would be helpful.

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