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• DB optimization to use it as a queue

  - by anony

  We have a table called worktable which has some columns(key(primary key), ptime, aname, status, content) we have something called producer which puts in rows in this table and we have consumer which does an order-by on the key column and fetches the first row which has status as 'pending'. The consumer does some processing on this row: 1. updates status to "processing" 2. does some processing using content 3. deletes the row we are facing contention issues when we try to run multiple consumers(probably due to the order-by which does a full table scan)... using Advanced queues would be our next step but before we go there we want to check what is the max throughput we can achieve with multiple consumers and producer on the table. What are the optimizations we can do to get the best numbers possible? Can we do an in-memory processing where a consumer fetches 1000 rows at a time processes and deletes? will that improve? What are other possibilities? partitioning of table? parallelization? Index organized tables?...

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• operator overloading and inheritance

  - by user168715

  I was given the following code: class FibHeapNode { //... // These all have trivial implementation virtual void operator =(FibHeapNode& RHS); virtual int operator ==(FibHeapNode& RHS); virtual int operator <(FibHeapNode& RHS); }; class Event : public FibHeapNode { // These have nontrivial implementation virtual void operator=(FibHeapNode& RHS); virtual int operator==(FibHeapNode& RHS); virtual int operator<(FibHeapNode& RHS); }; class FibHeap { //... int DecreaseKey(FibHeapNode *theNode, FibHeapNode& NewKey) { FibHeapNode *theParent; // Some code if (theParent != NULL && *theNode < *theParent) { //... } //... return 1; } }; Much of FibHeap's implementation is similar: FibHeapNode pointers are dereferenced and then compared. Why does this code work? (or is it buggy?) I would think that the virtuals here would have no effect: since *theNode and *theParent aren't pointer or reference types, no dynamic dispatch occurs and FibHeapNode::operator< gets called no matter what's written in Event.

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• In Gtk#, why might VALID_ITER fail even after I check it with IterIsValid?

  - by Matthew

  I have a convenience function in my TreeView that looks something like this: Card GetCardFromPath (TreePath path) { TreeIter iter; if (path == null || !Model.GetIter (out iter, path)) return null; if ((Model as TreeModelSort).IterIsValid (iter)) return (Card) Model.GetValue (iter, 0); return null; } Most of the time this works without any errors. But when it is called directly after the Model is changed, line 8 gives me these Gtk runtime errors: [Fatal 16:53:02.448] [Gtk] gtk_list_store_get_value: assertion `VALID_ITER (iter, list_store)' failed [Fatal 16:53:02.449] [GLib-GObject] g_value_unset: assertion `G_IS_VALUE (value)' failed As far as I can tell, I shouldn't even need to check IterIsValid, because I'm already checking the return value of Model.GetIter. Even so, how can VALID_ITER fail in a function that only gets called if IterIsValid returns true? If it makes a difference, the Model is a TreeModelSort, which sorts a TreeModelFilter, which filters a ListStore. The error occurs when GetCardFromPath is called from HandleSelectionChanged when multiple rows have just been removed from the ListStore. It doesn't seem to prevent anything from working properly, but having a cascade of errors whenever I remove multiple rows isn't really ideal.

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• Do I need to using locking against integers in c++ threads

  - by Shane MacLaughlin

  The title says it all really. If I am accessing a single integer type (e.g. long, int, bool, etc...) in multiple threads, do I need to use a synchronisation mechanism such as a mutex to lock them. My understanding is that as atomic types, I don't need to lock access to a single thread, but I see a lot of code out there that does use locking. Profiling such code shows that there is a significant performance hit for using locks, so I'd rather not. So if the item I'm accessing corresponds to a bus width integer (e.g. 4 bytes on a 32 bit processor) do I need to lock access to it when it is being used across multiple threads? Put another way, if thread A is writing to integer variable X at the same time as thread B is reading from the same variable, is it possible that thread B could end up a few bytes of the previous value mixed in with a few bytes of the value being written? Is this architecture dependent, e.g. ok for 4 byte integers on 32 bit systems but unsafe on 8 byte integers on 64 bit systems? Edit: Just saw this related post which helps a fair bit.

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• Mgmt wants to re-title my position: Any help...? [closed]

  - by JohnFlyTN

  Management here wants to re-title my position, since I'm doing quite a bit of different work than was originally planned. They want my input. After a quick glance over my skill set and job duties, what would we need to describe this position as? I'll just list things I'm at least proficient in, I will not list things I have a passing knowledge of. About me : ~10 years software development. Languages : C, C++, Perl, PHP, C#, TCL, Unix shell scripting, SQL (TSQL, PLSQL) Systems : MS-Dos, Windows 3.1 to 7 for client, NT 4 to 2008 for server, OS/2, IBM MVS & z/OS, Linux ( multiple distros), AIX Current position: I do all sorts of in-house software. The range is single user apps to large systems spanning multiple OS's. One of the larger projects I've designed and coded is about 100k lines of C#, and a database where I have been the sole designer and maintainer. I have near total freedom to design as I see fit, restraints are usually budgetary. Skills required to replace me in my current role: Windows and Unix admin, Database design, .NET up to 3.5 (C#, ASP.NET), C++, Perl, good skills in designing large and efficient data processing systems. Given this small level of information what would you see this as being titled? (is more information required to render a decision?)

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• What do I do about a Java program that spawned two instaces of itself?

  - by user288915

  I have a java JAR file that is triggered by a SQL server job. It's been running successfully for months. The process pulls in a structured flat file to a staging database then pushes that data into an XML file. However yesterday the process was triggered twice at the same time. I can tell from a log file that gets created, it looks like the process ran twice simultaneously. This caused a lot of issues and the XML file that it kicked out was malformed and contained duplicate nodes etc. My question is, is this a known issue with Java JVM's spawning multiple instances of itself? Or should I be looking at sql server as the culprit? I'm looking into 'socket locking' or file locking to prevent multiple instances in the future. This is the first instance of this issue that I've ever heard of. More info: The job is scheduled to run every minute. The job triggers a .bat file that contains the java.exe - jar filename.jar The java program runs, scans a directory for a file and then executes a loop to process if the file if it finds one. After it processes the file it runs another loop that kicks out XML messages. I can provide code samples if that would help. Thank you, Kevin

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• Looping through a method without for/foreach/while

  - by RichK

  Is there a way of calling a method/lines of code multiple times not using a for/foreach/while loop? For example, if I were to use to for loop: int numberOfIterations = 6; for(int i = 0; i < numberOfIterations; i++) { DoSomething(); SomeProperty = true; } The lines of code I'm calling don't use 'i' and in my opinion the whole loop declaration hides what I'm trying to do. This is the same for a foreach. I was wondering if there's a looping statement I can use that looks something like: do(6) { DoSomething(); SomeProperty = true; } It's really clear that I just want to execute that code 6 times and there's no noise involving index instantiating and adding 1 to some arbitrary variable. As a learning exercise I have written a static class and method: Do.Multiple(int iterations, Action action) Which works but scores very highly on the pretentious scale and I'm sure my peers wouldn't approve. I'm probably just being picky and a for loop is certainly the most recognisable, but as a learning point I was just wondering if there (cleaner) alternatives. Thanks. (I've had a look at this thread, but it's not quite the same) http://stackoverflow.com/questions/2248985/using-ienumerable-without-foreach-loop

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• Turn based synchronization between threads

  - by Amarus

  I'm trying to find a way to synchronize multiple threads having the following conditions: * There are two types of threads: 1. A single "cyclic" thread executing an infinite loop to do cyclic calculations 2. Multiple short-lived threads not started by the main thread * The cyclic thread has a sleep duration between each cycle/loop iteration * The other threads are allowed execute during the inter-cycle sleep of the cyclic thread: - Any other thread that attempts to execute during an active cycle should be blocked - The cyclic thread will wait until all other threads that are already executing to be finished Here's a basic example of what I was thinking of doing: // Somewhere in the code: ManualResetEvent manualResetEvent = new ManualResetEvent(true); // Allow Externally call CountdownEvent countdownEvent = new CountdownEvent(1); // Can't AddCount a CountdownEvent with CurrentCount = 0 void ExternallyCalled() { manualResetEvent.WaitOne(); // Wait until CyclicCalculations is having its beauty sleep countdownEvent.AddCount(); // Notify CyclicCalculations that it should wait for this method call to finish before starting the next cycle Thread.Sleep(1000); // TODO: Replace with actual method logic countdownEvent.Signal(); // Notify CyclicCalculations that this call is finished } void CyclicCalculations() { while (!stopCyclicCalculations) { manualResetEvent.Reset(); // Block all incoming calls to ExternallyCalled from this point forward countdownEvent.Signal(); // Dirty workaround for the issue with AddCount and CurrentCount = 0 countdownEvent.Wait(); // Wait until all of the already executing calls to ExternallyCalled are finished countdownEvent.Reset(); // Reset the CountdownEvent for next cycle. Thread.Sleep(2000); // TODO: Replace with actual method logic manualResetEvent.Set(); // Unblock all threads executing ExternallyCalled Thread.Sleep(1000); // Inter-cycles delay } } Obviously, this doesn't work. There's no guarantee that there won't be any threads executing ExternallyCalled that are in between manualResetEvent.WaitOne(); and countdownEvent.AddCount(); at the time the main thread gets released by the CountdownEvent. I can't figure out a simple way of doing what I'm after, and almost everything that I've found after a lengthy search is related to producer/consumer synchronization which I can't apply here.

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• Does using functional languages help against computing values repeatedly?

  - by sharptooth

  Consider a function f(x,y): f(x,0) = x*x; f(0,y) = y*(y + 1); f(x,y) = f(x,y-1) + f(x-1,y); If one tries to implement that recursively in some language like C++ he will encounter a problem. Suppose the function is first called with x = x0 and y = y0. Then for any pair (x,y) where 0 <= x < x0 and 0 <= y < y0 the intermediate values will be computed multiple times - recursive calls will form a huge tree in which multiple leaves will in fact contain the same pairs (x,y). For pairs (x,y) where x and y are both close to 0 values will be computed numerous times. For instance, I tested a similar function implemented in C++ - for x=20 and y=20 its computation takes about 4 hours (yes, four Earth hours!). Obviously the implementation can be rewritten in such way that repeated computation doesn't occur - either iteratively or with a cache table. The question is: will functional languages perform any better and avoid repeated computations when implementing a function like above recursively?

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• Free cross-platform library to convert numbers (money amounts) to words?

  - by bialix

  I'm looking for cross-platform library which I can use in my C application to convert money amounts (e.g. $123.50) to words (one hundred twenty three dollars and fifty cents). I need support for multiple currencies: dollars, euros, UK pounds etc. Although I understand this is not hard at all to write my own implementation, but I'd like to avoid reinventing wheel. I've tried to google it, but there is too much noise related to MS Word converters. Can anybody suggest something? UPDATE numerous comments suggest to write my own implementation because it's really easy task. And I agree. My point was about support of multiple currencies in the same time and different business rules to spell the amounts (should be fractional part written as text or numbers? etc.) As I understand serious business applications have such library inside, but I think there is nothing open-source available, maybe because it seems as very easy task. I'm going to write my own libary and then open-source it. Thanks to all.

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• Retrieve POST data without knowing exact number of fields

  - by James

  Hi all! I'm creating an online poll from scratch which will be held in a database. I'm working on getting a system set up so someone can create a new poll. I will be having the user fill out a simple HTML form with the Questions and Answers (there may be several answers). The user will be able to add multiple questions and multiple answers for each question. As the total number of questions and answers will be decided by the user, I need to create some clever PHP to cater for this - however many there are. When dealing with a static number of questions, it's simple. But I'm having trouble thinking of a way to get all the POST data into individual PHP variables so I can process them. I was thinking of using a foreach loop, anyone got any ideas? Sorry for the long winded description! If anyone needs anything clarified, I'd be happy to do so. My problem is that I can't get my head around how to deal with the POST values when I don't know exactly which element of the array will contain what. If things were static with a set number of questions and answers, I'd know $_POST[0] was Question1, etc Thank you! =)

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• Custom API requirement

  - by Jonathan.Peppers

  We are currently working on an API for an existing system. It basically wraps some web-requests as an easy-to-use library that 3rd party companies should be able to use with our product. As part of the API, there is an event mechanism where the server can call back to the client via a constantly-running socket connection. To minimize load on the server, we want to only have one connection per computer. Currently there is a socket open per process, and that could eventually cause load problems if you had multiple applications using the API. So my question is: if we want to deploy our API as a single standalone assembly, what is the best way to fix our problem? A couple options we thought of: Write an out of process COM object (don't know if that works in .Net) Include a second exe file that would be required for events, it would have to single-instance itself, and open a named pipe or something to communicate through multiple processes Extract this exe file from an embedded resource and execute it None of those really seem ideal. Any better ideas?

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• issue with tab bar view displaying a compound view

  - by ambertch

  I created a tab bar application, and I make the first tab a table. So I create a tableView controller, and go about setting the class identity of the view controller for the first tab to my tableView controller. This works fine, and I see the contents of the table filling up the whole screen. However, this is not what I actually want in the end goal - I would like a compound window having multiple views: - the aforementioned table - a custom view with data in it So what I do is create a nib for this content (call it contentNib), change the tab's class from the tableView controller to a generic UIViewController, and set the nib of that tab to this new contentNib. In this new contentNib I drag on a tableView and set File's Owner to the TableViewController. I then link the dataSource and delegate to file's owner (which is TableViewController). Surprisingly this does not work and I receive the error: **Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[UIViewController tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0x3b0f910'** This is bewildering to me since the file's owner is the TableViewController, which has been assigned to be both the dataSource and delegate. Does someone have either insight into my confusions, or a link to an example of how to have a compound view include a tableView? *update* I see this in the Apple TableView programming guide: "Note: You should use a UIViewController subclass rather than a subclass of UITableViewController to manage a table view if the view to be managed is composed of multiple subviews, one of which is a table view. The default behavior of the UITableViewController class is to make the table view fill the screen between the navigation bar and the tab bar (if either are present)." <----- I don't really get what this is telling me to do though... if someone can explain or point me to an example I'd be much appreciated!

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• Low Throughput on Windows Named Pipe Over WAN

  - by MichaelB76

  I'm having problems with low performance using a Windows named pipe. The throughput drops off rapidly as the network latency increases. There is a roughly linear relationship between messages sent per second and round trip time. It seems that the client must ack each message before the server will send the next one. This leads to very poor performance, I can only send 5 (~100 byte) messages per second over a link with an RTT of 200 ms. The pipe is asynchronous, using multiple overlapped write operations (and multiple overlapped reads at the client end), but this is not improving throughput. Is it possible to send messages in parallel over a named pipe? The pipe is created using PIPE_TYPE_MESSAGE, would PIPE_READMODE_BYTE work better? Is there any other way I can improve performance? This is a deployed solution, so I can't simply replace the pipe with a socket connection (I've read that Windows named pipe aren't recommended for use over a WAN, and I'm wondering if this is why). I'd be grateful for any help with this matter.

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• Convert IIS / Tomcat Web Application to a multi-server environment.

  - by bill_the_loser

  I have an existing web application built in .Net, running on IIS that leverages a java servlet that we have running on Tomcat 5.5. We need to scale the application and I'm confused about what relates to our situation and what we need to do to get the servlet running on multiple servers. Right now I have 4 servers that can each individually process results, it almost seems like all I should have to do is add the ajp13 worker processes from three additional machines to the machine hosting the load balancer worker. But I can't imagine it should be that easy. What do I need to do to distribute the Tomcat load to the extra three machines? Thanks. Update: The current configuration is using a workers2.properties configuration file. From all of the documentation online I have not been able to determine the distinction between the workers.properties and the workers2.properties. Most of the examples that I have found are configuring the workers.properties and revolve around adding workers and registering them in the worker.list element. The workers2.properties does not appears to have a worker.list element and the syntax is different enough between the workers.properties and the workers2.properties that I'm doubtful that I can add that element. If I just add my multiple AJP workers to the workers2.properties file do I need to worry about the apparent lack of a worker.list element? [ajp13:localhost:8009] channel=channel.socket:localhost:8009 group=lb [ajp13:host2.mydomain.local:8009] channel=channel.socket:host2.mydomain.local:8009 group=lb [ajp13:host3.mydomain.local:8009] channel=channel.socket:host3.mydomain.local:8009 group=lb A couple of side notes... One I've noticed that sometime Tomcat doesn't seem to reload my changes and I don't know why. Also, I have no idea why this configuration has a workers2.properties and not a workers.properties. I've been assuming that it's based on version but I haven't seen anything to back up that assumption.

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• Is there a quality, file-size, or other benefit to JPEG sizes being multiples of 8px or 16px?

  - by davebug

  The JPEG compression encoding process splits a given image into blocks of 8x8 pixels, working with these blocks in future lossy and lossless compressions. [source] It is also mentioned that if the image is a multiple 1MCU block (defined as a Minimum Coded Unit, 'usually 16 pixels in both directions') that lossless alterations to a JPEG can be performed. [source] I am working with product images and would like to know both if, and how much benefit can be derived from using multiples of 16 in my final image size (say, using an image with size 480px by 360px) vs. a non-multiple of 16 (such as 484x362). In this example I am not interested in further alterations, editing, or recompression of the final image. To try to get closer to a specific answer where I know there must be largely generalities: Given a 480x360 image that is 64k and saved at maximum quality in Photoshop [example]: Can I expect any quality loss from an image that is 484x362 What amount of file size addition can I expect (for this example, the additional space would be white pixels) Are there any other disadvantages to growing larger than the 8px grid? I know it's arbitrary to use that specific example, but it would still be helpful (for me and potentially any others pondering an image size) to understand what level of compromise I'd be dealing with in breaking the non-8px grid. The key issue here is a debate I've had is whether 8-pixel divisible images are higher quality than images that are not divisible by 8-pixels.

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• Help with simple javascript loop

  - by Gabriel

  Hello, I have a simple javascript that I'd like to loop for multiple elements. Here's my code: <script type='text/javascript'> for(i = 1; i < 100; i++) { $('#link'+i).click(function() { $('#container').removeClass(); $('#container').addClass('templateid'+i); }); } </script> What I'd like to achieve is the same addClass function for multiple id's (e.g. link2, link3, link4), with the corresponding class (e.g. template2, template3, template4). Any help would be hugely appreciated! For reference, an individual call like this one, does work, so I don't see why the loop above doesn't function the same: <script type='text/javascript'> $('#link2').click(function() { $('#container').removeClass(); $('#container').addClass('templateid2'); }); </script>

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• How to initialize list with parent child relation

  - by user2917702

  Let's say I have the following classes. public class Parent { public string name; IList<Children> children; } public class Child { public string parentName; public int age; } As it is understandable, each parent can have multiple children, and we can have multiple parents. What is the best way to initialize these classes? Is it better to get all of the parents, and all of the children from database then use LINQ? IList<Parent> parents = GetParents()//assume this gets parents from db IList<Child> children = GetChildren() //assume this gets children from db foreach(Parent parent in parents) { parent.children = children.Where(x=>x.parentName==parent.name).ToList(); } or get all of the parents and iterate through each parent to query database by parentName to get children information? Due to requirement that I have, I cannot use datatable or dataset; I can only use datareader. IList<Parent> parents = GetParents()//assume this gets parents from db foreach(Parent parent in parents) { parent.children = GetChildrenByParentName();//assume this gets parents from db by parentName } Thank you

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• Good C++ array class for dealing with large arrays of data in a fast and memory efficient way?

  - by Shane MacLaughlin

  Following on from a previous question relating to heap usage restrictions, I'm looking for a good standard C++ class for dealing with big arrays of data in a way that is both memory efficient and speed efficient. I had been allocating the array using a single malloc/HealAlloc but after multiple trys using various calls, keep falling foul of heap fragmentation. So the conclusion I've come to, other than porting to 64 bit, is to use a mechanism that allows me to have a large array spanning multiple smaller memory fragments. I don't want an alloc per element as that is very memory inefficient, so the plan is to write a class that overrides the [] operator and select an appropriate element based on the index. Is there already a decent class out there to do this, or am I better off rolling my own? From my understanding, and some googling, a 32 bit Windows process should theoretically be able address up to 2GB. Now assuming I've 2GB installed, and various other processes and services are hogging about 400MB, how much usable memory do you think my program can reasonably expect to get from the heap? I'm currently using various flavours of Visual C++.

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• Error "initializer element is not constant" when trying to initialize variable with const

  - by tomlogic

  I get an error on line 6 (initialize my_foo to foo_init) of the following program and I'm not sure I understand why. typedef struct foo_t { int a, b, c; } foo_t; const foo_t foo_init = { 1, 2, 3 }; foo_t my_foo = foo_init; int main() { return 0; } Keep in mind this is a simplified version of a larger, multi-file project I'm working on. The goal was to have a single constant in the object file, that multiple files could use to initialize a state structure. Since it's an embedded target with limited resources and the struct isn't that small, I don't want multiple copies of the source. I'd prefer not to use: #define foo_init { 1, 2, 3 } I'm also trying to write portable code, so I need a solution that's valid C89 or C99. Does this have to do with the ORGs in an object file? That initialized variables go into one ORG and are initialized by copying the contents of a second ORG? Maybe I'll just need to change my tactic, and have an initializing function do all of the copies at startup. Unless there are other ideas out there?

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• Why doesn't Firefox redownload images already on a page?

  - by vvo

  Hello, i just read this article : https://developer.mozilla.org/en/HTTP_Caching_FAQ There's a firefox behavior (and some other browsers i guess) i'd like to understand : if i take any webpage and try to insert the same image multiple times in javascript, the image is only downloaded ONCE even if i specifiy all needed headers to say "do no ever use cache". (see article) I know there are workarounds (like addind query strings to end of urls etc) but why do firefox act like that, if i say that an image do not have to be cached, why is the image still taken from cache when i try to re-insert it ? Plus, what cache is used for this ? (I guess it's the memory cache) Is this behavior the same for dynamic inclusion for example ? ANSWSER IS NO :) I just tested it and the same headers for a js script will make firefox redownload it each time you append the script to the DOM. PS: I know you're wondering WHY i need to do that (appending same image multiple times and force to redownload but this is the way our app works) thank you The good answer is : firefox will store images for the current page load in the memory cache even if you specify he doesnt have to cache them. You can't change this behavior but this is odd because it's not the same for javascript files for example Could someone explain or link to a document describing how firefox cache WORKS?

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• when is a v-table created in C++?

  - by saminny

  When exactly does the compiler create a virtual function table? 1) when the class contains at least one virtual function. OR 2) when the immediate base class contains at least one virtual function. OR 3) when any parent class at any level of the hierarchy contains at least one virtual function. A related question to this: Is it possible to give up dynamic dispatch in a C++ hierarchy? e.g. consider the following example. #include <iostream> using namespace std; class A { public: virtual void f(); }; class B: public A { public: void f(); }; class C: public B { public: void f(); }; Which classes will contain a V-Table? Since B does not declare f() as virtual, does class C get dynamic polymorphism?

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• Considering moving from Java/Spring MVC to Grails

  - by MDS

  I'm currently using Java & Spring (MVC) to create a webapp, and I'm considering moving to Grails. I'd appreciate feedback/insight on the following: I have multiple application contexts in the current Java/Spring webapp that I load through the web.xml ContextLoaderListener; is it possible to have multiple application contexts in Grails? If, yes, how? This webapp extensively uses a CXF restful web service and the current Java/Spring webapp uses the bundled CXF HTTP client. Can I continue to use the (Java) CXF HTTP Client in Grails? I implemented Spring Security using a custom implementation of UserDetails and UserDetailsService, can I re-use these implementations in Grails "as is" or must I re-implement them? There is an instance where I've relied on Spring's jdbc template (rather than the available ORM) and an additional data source I defined in app context, can I re-use this in Grails? I plan on using Maven as the project management tool; are there any issues of using Maven with Grails where there is a combination of groovy and java?

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• In Rails, how to respect :scope when using validates_uniqueness_of in an embedded object form?

  - by mkirk

  I have a Book model, which has_many Chapters (which belong_to a Book). I want to ensure uniqueness of Chapter titles, but only within the scope of a single book. The catch is that the form for creating chapters is embedded in the Book model's form (The Book model accepts_nested_attributes_for :chapters). Within the Chapter model: validates_uniqueness_of( :chapter_title, :scope = :book_id, :case_sensitive = false, :message = "No book can have multiple chapters with the same title.") However, when I submit the Book creation form (which also includes multiple embedded Chapter forms), if the chapter title exists in another chapter for a different book, I fail the validation test. Book.create( :chapters => [ Chapter.new(:title => "Introduction"), Chapter.new(:title => "How to build things") => Book 1 successfully created Book.create( :chapters => [ Chapter.new(:title => "Introduction"), Chapter.new(:title => "Destroy things") => Book 2 fails to validate second_book = Book.create( :chapters => [ Chapter.new(:title => "A temporary Introduction title"), Chapter.new(:title => "Destroy things") => Book 2 succesfully created second_book.chapters[0].title= "Introduction" => success second_book.chapters.save => success second_book.save => success Can anyone shed some light on how to do this? Or why it's happening?

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• initialize jquery slider with hidden input value from database.

  - by ludwigs3rd

  I'm using a slider as user input for a screen. Basically it's a bulk update screen where there is a table with multiple rows, thus multiple sliders. I created it so that the hidden value is what gets posted in the form. <td> <input class="percentageProvidedHidden" type="hidden" name='<%= "Values[" + i + "].Percentage" %>' value='<%=item.Percentage %>' /> <div class="percentageProvidedSlider"></div> </td> I have the update working just fine (move slider changes hidden input value, submit, values are updated in db), however, I can't get the damn thing to initialize with the value of the hidden input (note the "value: " parameter below). In this case I think $(this) isn't actually $('percentageProvidedSlider') but the page itself. Can someone help me get the slider value to initialize with the hidden input field? I'm using ASP .Net MVC 2 so if there are any methods I should try with that I welcome them as well. $('.percentageProvidedSlider').slider( { min: 0, max: 100, step: 25, value: $(this).parents('tr').find('input.percentageProvidedHidden').val(), slide: function(e, ui) { var mypos = ui.value; $(this).find('.ui-slider-handle').text(ui.value); }, change: function(event, ui) { var myVal = $(this).slider("option", "value"); $(this).parents('tr').find('input.percentageProvidedHidden').val(myVal); var myDropDown = $(this).parents('tr').find('select.verified'); } });

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