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  • How do I pass references as method parameters across AppDomains?

    - by Thiado de Arruda
    I have been trying to get the following code to work(everything is defined in the same assembly) : namespace SomeApp{ public class A : MarshalByRefObject { public byte[] GetSomeData() { // } } public class B : MarshalByRefObject { private A remoteObj; public void SetA(A remoteObj) { this.remoteObj = remoteObj; } } public class C { A someA = new A(); public void Init() { AppDomain domain = AppDomain.CreateDomain("ChildDomain"); string currentAssemblyPath = Assembly.GetExecutingAssembly().Location; B remoteB = domain.domain.CreateInstanceFromAndUnwrap(currentAssemblyPath,"SomeApp.B") as B; remoteB.SetA(someA); // this throws an ArgumentException "Object type cannot be converted to target type." } } } What I'm trying to do is pass a reference of an 'A' instance created in the first AppDomain to the child domain and have the child domain execute a method on the first domain. In some point on 'B' code I'm going to call 'remoteObj.GetSomeData()'. This has to be done because the 'byte[]' from 'GetSomeData' method must be 'calculated' on the first appdomain. What should I do to avoid the exception, or what can I do to achieve the same result?

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  • jQuery - Wait until image loads before performing function

    - by Steven
    I'm trying to create a simple portfolio page. I have a list of thumbs and an image. When you click on a thumb, the image will change. When a thumbnail is clicked, I'd like to have the image fade out, wait until the image is loaded, then fade back in. The problem I have right now is that some of the images are pretty big, so it fades out, then fades back in immediately, sometimes while the image is still loading. I'd like to avoid using setTimeout, since sometimes an image will load faster or slower than the time I set. Here's my code: $(function() { $('img#image').attr("src", $('ul#thumbs li:first img').attr("src")); $('ul#thumbs li img').click(function() { $('img#image').fadeOut(700); var src = $(this).attr("src"); $('img#image').attr("src", src); $('img#image').fadeIn(700); }); }); <img id="image" src="" alt="" /> <ul id="thumbs"> <li><img src="/images/thumb1.png" /></li> <li><img src="/images/thumb2.png" /></li> <li><img src="/images/thumb3.png" /></li> </ul>

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  • Authentication and Security in my website - need advice please.

    - by Ichirichi
    Hi, I am using database with a list of username/passwords, and a simple web form that allows for users to enter their username/password. When they submit the page, I simply do a stored procedure check to authenticate. If they are authorised, then their user details (e.g. username, dob, address, company address, other important info) are stored in a custom User object and then in a session. This custom User object that I created is used throughout the web application, and also in a sub-site (session sharing). My question/problems are: Is my method of authentication the correct way to do things? I find users complaining that their session have expired although they "were not idle", possibly due the app pool recycling? They type large amounts of text and find that their session had expired and thus lose all the text typed in. I am uncertain whether the session does really reset sporadically but will Forms Authentication using cookies/cookiless resolve the issue? Alternatively should I build and store the User Object in a session, cookie or something else instead in order to be more "correct" and avoid cases like in point #2. If I go down the Forms Authentication route, I believe I cannot store my custom User object in a Forms Authentication cookie so does it mean I would store the UserID and then recreate the user object on every page? Would this not be a huge increase on the server load? Advice and answers much appreciated. L

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  • Doing a virus check on a file from a build script

    - by the_mandrill
    I would like to be be able to invoke a virus check as the final stage of the build process (please don't question why a dev machine would get a virus, it's just a belt-and-braces approach to avoid the risk of getting sued by customers...). Also I'd like the option of having AV on a machine but switching the auto file system protection off (at least for the build directories). What I would like is a generic way of scanning a file using whatever AV system is in place. I'm assuming that there's an Windows API to do this, given that Windows detects the presence of an AV system, and browsers such as Firefox invoke a virus scan whenever a file is downloaded. So what's the API that they're using? There's the Microsoft AntiVirus API but that seems to be specific to Office documents. Does the approach involve using WMI? (and if you can detect the AV provider from there, how do you then invoke it to scan a file?) I know that I could write the script to manually call the AV scanner that I know to be installed, but as an intellectual exercise I'm more interested to know how apps like Firefox are doing this.

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  • My method is too specific. How can I make it more generic?

    - by EricBoersma
    I have a class, the outline of which is basically listed below. import org.apache.commons.math.stat.Frequency; public class WebUsageLog { private Collection<LogLine> logLines; private Collection<Date> dates; WebUsageLog() { this.logLines = new ArrayList<LogLine>(); this.dates = new ArrayList<Date>(); } SortedMap<Double, String> getFrequencyOfVisitedSites() { SortedMap<Double, String> frequencyMap = new TreeMap<Double, String>(Collections.reverseOrder()); //we reverse order to sort from the highest percentage to the lowest. Collection<String> domains = new HashSet<String>(); Frequency freq = new Frequency(); for (LogLine line : this.logLines) { freq.addValue(line.getVisitedDomain()); domains.add(line.getVisitedDomain()); } for (String domain : domains) { frequencyMap.put(freq.getPct(domain), domain); } return frequencyMap; } } The intention of this application is to allow our Human Resources folks to be able to view Web Usage Logs we send to them. However, I'm sure that over time, I'd like to be able to offer the option to view not only the frequency of visited sites, but also other members of LogLine (things like the frequency of assigned categories, accessed types [text/html, img/jpeg, etc...] filter verdicts, and so on). Ideally, I'd like to avoid writing individual methods for compilation of data for each of those types, and they could each end up looking nearly identical to the getFrequencyOfVisitedSites() method. So, my question is twofold: first, can you see anywhere where this method should be improved, from a mechanical standpoint? And secondly, how would you make this method more generic, so that it might be able to handle an arbitrary set of data?

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  • Consecutive absences in MySQL

    - by pepersview
    Hi, I have 2 tables in my db: students and absences. In students: id_student, s_name; and in absences: id_student, date, day(the day of the week as number-it's not so important); I would like to get the students that were absent for more than 2 days consecutive and the dates. At the moment I have the next query: /*To control when the days are in the same week*/ SELECT id_student, date, dayname(date),date_add(date, INTERVAL 1 DAY) AS a, dayname(date_add(date, INTERVAL 1 DAY)) AS an, date_add(date, INTERVAL 2 DAY) AS b, dayname(date_add(date, INTERVAL 2 DAY)) AS bn FROM absences AS a WHERE id_student IN (SELECT id_student FROM absences WHERE id_student = a.id_student AND date = date_add(a.date, INTERVAL 1 DAY) ) AND id_student IN (SELECT id_student FROM absences WHERE id_student = a.id_student AND date = date_add(a.date,INTERVAL 2 DAY) ) UNION /*To control when the days jump to the next week*/ SELECT id_student, date, dayname(date),date_add(date, INTERVAL 3 DAY) AS a, dayname(date_add(date, INTERVAL 3 DAY)) AS an, date_add(date, INTERVAL 4 DAY) AS b, dayname(date_add(date, INTERVAL 4 DAY)) AS bn FROM absences AS a WHERE id_student IN (SELECT id_student FROM absences WHERE id_student = a.id_student AND date = date_add(a.date, INTERVAL 3 DAY) ) AND id_student IN (SELECT id_student FROM absences WHERE id_student = a.id_student AND date = date_add(a.date,INTERVAL 4 DAY) ) /* To avoid the case (Monday-Thursday-Friday) to be consider as consecutive days*/ AND WEEKDAY(date) !=0 Thanks

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  • Can it be important to call remove() on an EJB 3 stateless session bean? Perhaps on weblogic?

    - by Michael Borgwardt
    I'm in the process of migrating an EJB 2 application to EJB 3 (and what a satisfying task it is to delete all those deployment descriptors!). It used to run on Weblogic and now runs on Glassfish. The task is going very smoothly, but one thing makes me wary: The current code takes great care to ensure that EJBObject.remove() is called on the bean when it's done its job, and other developers have (unfortunately very vague) memories of "bad things" happening when that was not done. However, with EJB3, the implementation class does not implement EJBObject, so there is no remove() method to be called. And my understanding is that there isn't really any point at all in calling it on stateless session beans, since they are, well, stateless. Could these "bad things" have been weblogic-specific? If not, what else? Should I avoid the full EJB3 lightweightness and keep a remote interface that extends EJBObject? Or just write it off as cargo-cult programming and delete all those try/finally clauses? I'm leaning towards the latter, but now feeling very comfortable with it.

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  • "pseudo-atomic" operations in C++

    - by dan
    So I'm aware that nothing is atomic in C++. But I'm trying to figure out if there are any "pseudo-atomic" assumptions I can make. The reason is that I want to avoid using mutexes in some simple situations where I only need very weak guarantees. 1) Suppose I have globally defined volatile bool b, which initially I set true. Then I launch a thread which executes a loop while(b) doSomething(); Meanwhile, in another thread, I execute b=true. Can I assume that the first thread will continue to execute? In other words, if b starts out as true, and the first thread checks the value of b at the same time as the second thread assigns b=true, can I assume that the first thread will read the value of b as true? Or is it possible that at some intermediate point of the assignment b=true, the value of b might be read as false? 2) Now suppose that b is initially false. Then the first thread executes bool b1=b; bool b2=b; if(b1 && !b2) bad(); while the second thread executes b=true. Can I assume that bad() never gets called? 3) What about an int or other builtin types: suppose I have volatile int i, which is initially (say) 7, and then I assign i=7. Can I assume that, at any time during this operation, from any thread, the value of i will be equal to 7? 4) I have volatile int i=7, and then I execute i++ from some thread, and all other threads only read the value of i. Can I assume that i never has any value, in any thread, except for either 7 or 8? 5) I have volatile int i, from one thread I execute i=7, and from another I execute i=8. Afterwards, is i guaranteed to be either 7 or 8 (or whatever two values I have chosen to assign)?

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  • Can I set NHibernate's default "OrderBy" to be "CreatedDate" not "Id"?

    - by Chris F
    This is an oddball question I figure. Can I get NHibernate to ask SQL to sort data by CreatedDate by default unless I set an OrderBy in my HQL or Criteria? I'm interested in knowing whether this sort can be accomplished at the DB level to avoid bringing in LINQ. The reason is that I use GUIDs for Ids and when I do something like this: Sheet sheet = sheetRepository.Get(_someGUID); IList<SheetLineItems> lineItems = sheet.LineItems; to fetch all of the lineItems, they come back in whatever arbitrary way that SQL sorts that fetch, which I figure is GUID. At some point I'll add ordinals to my line items, but for now, I just want to use CreatedDate as the sort criteria. I don't want to be forced to do: IList<SheetLineItem> lineItems = sheetLineItemRepository.GetAll(_sheetGUID); and then writing that method to sort by CreatedDate. I figure if everything is just sorted on CreatedDate by default, that would be fine, unless specifically requested otherwise.

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  • Does the Java Memory Model (JSR-133) imply that entering a monitor flushes the CPU data cache(s)?

    - by Durandal
    There is something that bugs me with the Java memory model (if i even understand everything correctly). If there are two threads A and B, there are no guarantees that B will ever see a value written by A, unless both A and B synchronize on the same monitor. For any system architecture that guarantees cache coherency between threads, there is no problem. But if the architecture does not support cache coherency in hardware, this essentially means that whenever a thread enters a monitor, all memory changes made before must be commited to main memory, and the cache must be invalidated. And it needs to be the entire data cache, not just a few lines, since the monitor has no information which variables in memory it guards. But that would surely impact performance of any application that needs to synchronize frequently (especially things like job queues with short running jobs). So can Java work reasonably well on architectures without hardware cache-coherency? If not, why doesn't the memory model make stronger guarantees about visibility? Wouldn't it be more efficient if the language would require information what is guarded by a monitor? As i see it the memory model gives us the worst of both worlds, the absolute need to synchronize, even if cache coherency is guaranteed in hardware, and on the other hand bad performance on incoherent architectures (full cache flushes). So shouldn't it be more strict (require information what is guarded by a monitor) or more lose and restrict potential platforms to cache-coherent architectures? As it is now, it doesn't make too much sense to me. Can somebody clear up why this specific memory model was choosen? EDIT: My use of strict and lose was a bad choice in retrospect. I used "strict" for the case where less guarantees are made and "lose" for the opposite. To avoid confusion, its probably better to speak in terms of stronger or weaker guarantees.

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  • If the forms are nested ,i am not able to submit it in ie6

    - by jaan
    If the forms are nested ,i'm not able to submit it in ie6 <html> <body> <form id="mainform" action="form_action.asp"> <form id="subform" action="form_action1.asp"> <input type="submit" name="FirstName12" value="Mickey" /><br /> </form> First name: <input type="text" name="FirstName" value="Mickey" /> <br/> Last name: <input type="text" name="LastName" value="Mouse" /> <br/> <input type="submit" value="Submit" /> </form> </body> </html> I'm not able to submit the mainform using submit button in ie6. Not: But i can't avoid the nesting of forms.this code is just a sample Thanks in advance!

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  • Instantiate a form, then find it later, without showing it initially

    - by awilson53
    I am having a problem that is strange to me but hopefully is not so strange to someone else. : ) Some background: I am working on a simple IM client that allows the user to broadcast messages to multiple recipients. The goal is to create a chat form for each of the recipients containing the text of the broadcast message, then show that form only if the recipient responds to the broadcast-er. However, when the application receives a response then attempts to locate the form for that particular chat session (using Application.OpenForms) it cannot find it UNLESS I .Show at the time it is created. I would like to avoid having to show this form when it is created because this means that the user will see a flash on the screen. The form doesn't seem to really be created until I show it, but it would seem there has to be a way to do this without showing first. Can anyone assist? I can provide code snippets if needed, I didn't in this post because this feels more like a conceptual misunderstanding on my part than a bug in the code. Thanks in advance!

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  • wpautop() - when shortcode attributes are on new lines -breaks args array

    - by Luca
    I have a custom shortcode tag with a few attributes, and I would like to be able to display its attributes on new lines - to make it more readable to content editors: [component attr1 ="value1" attr2 ="value of the second one" attr3 ="another" attr4 ="value" ... attrN ="valueN"] The reason behind this requirement is that a few attributes might be quite verbose in content. Unfortunately, wpautop() adds some nasty extra markup that breaks the args array like this (using php print_r($args)): Array ( [0] => attr1 [1] => ="value1" /> [3] => attr2 = [4] => "value [5] => of [6] => the [7] => second [8] => one" /> [10] => "" //...and more like this) I've tried with the attributes inline: [component attr1 ="value1" attr2 ="value of the second one" ="value"... attrN ="valueN"] and the output is as expected: Array ( [attr1] => value1 [attr2] => value of the second one [attr3] => //...and so on) is there any way to have the attributes intented and avoid that extra markup that breaks the $args array?

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  • C++ map performance - Linux (30 sec) vs Windows (30 mins) !!!

    - by sonofdelphi
    I need to process a list of files. The processing action should not be repeated for the same file. The code I am using for this is - using namespace std; vector<File*> gInputFileList; //Can contain duplicates, File has member sFilename map<string, File*> gProcessedFileList; //Using map to avoid linear search costs void processFile(File* pFile) { File* pProcessedFile = gProcessedFileList[pFile->sFilename]; if(pProcessedFile != NULL) return; //Already processed foo(pFile); //foo() is the action to do for each file gProcessedFileList[pFile->sFilename] = pFile; } void main() { size_t n= gInputFileList.size(); //Using array syntax (iterator syntax also gives identical performance) for(size_t i=0; i<n; i++){ processFile(gInputFileList[i]); } } The code works correctly, but... My problem is that when the input size is 1000, it takes 30 minutes - HALF AN HOUR - on Windows/Visual Studio 2008 Express (both Debug and Release builds). For the same input, it takes only 40 seconds to run on Linux/gcc! What could be the problem? The action foo() takes only a very short time to execute, when used separately. Should I be using something like vector::reserve for the map?

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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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  • Delphi static method of a class returning property value

    - by mitko.berbatov
    I'm making a Delphi VCL application. There is a class TStudent where I have two static functions: one which returns last name from an array of TStudent and another one which returns the first name of the student. Their code is something like: class function TStudent.FirstNameOf(aLastName: string): string; var i : integer; begin for i := 0 to Length(studentsArray) - 1 do begin if studentsArray[i].LastName = aLastName then begin result := studentsArray[i].FirstName; Exit; end; end; result := 'no match was found'; end; class function TStudent.LastNameOf(aFirstName: string): string; var i : integer; begin for i := 0 to Length(studentsArray) - 1 do begin if studentsArray[i].FirstName = aFirstName then begin result := studentsArray[i].LastName; Exit; end; end; result := 'no match was found'; end; My question is how can I avoid writing almost same code twice. Is there any way to pass the property as parameter of the functions.

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  • Generating HTML Programmatically in C#, Targeting Printed Reports

    - by John Passaniti
    I've taken over a C# (2.0) code base that has the ability to print information. The code to do this is insanely tedious. Elements are drawn onto each page, with magic constants representing positioning. I imagine the programmer sitting with a ruler, designing each page by measuring and typing in the positions. And yes, one could certainly come up with some nice abstractions to make this approach rational. But I am looking at a different method. The idea is that I'll replace the current code that prints with code that generates static HTML pages, saves them to a file, and then launches the web browser on that file. The most obvious benefit is that I don't have to deal with formatting-- I can let the web browser do that for me with tags and CSS. So what I am looking for is a very lightweight set of classes that I can use to help generate HTML. I don't need anything as heavyweight as HTMLTextWriter. What I'm looking for is something to avoid fragments like this: String.Format("<tr><td>{0}</td><td>{1}</td></tr>", foo, bar); And instead take have this kind of feel: ... table(). tr(). td(foo). td(bar) Or something like that. I've seen lightweight classes like that for other languages but can't find the equivalent (or better) for C#. I can certainly write it myself, but I'm a firm believer in not reinventing wheels. Know anything like this? Know anything better than this?

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  • How to gracefully handle YouTube thumbnail broken images when videos are taken down?

    - by mrjf
    Our site contains some lists of YouTube videos with their thumbnails linked to the movies themselves. We fetch the thumbnail URLs from the YouTube API, and hotlink to them in situ on YouTube's servers. So our image tags look like: <img src="http://i.ytimg.com/vi/o6CHqSN7O-o/2.jpg" alt="" width="133" height="78" /> The problem is that sometimes a video gets removed -- and so does the thumbnail. We don't know when that might happen, and our thumbnails just turn into broken images. How can we handle this? There are a number of solutions: Download thumbnails and store them locally -- movie won't work, but that's ok, it will explain it was removed, and we avoid the broken image Check periodically with the API to see if the image thumbnail has changed -- if it no longer exists, substitute our own "movie removed" thumbnail. This is pretty heavy on the API calling! Use JavaScript to replace broken images (don't like this one much) Our ideal solution would be to point the img src to a location on YouTube that would display a friendly "move removed" image when a movie goes down. However, that doesn't seem to exist. Anyone else dealt with this? Thanks!

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  • Not crawling the same content twice

    - by sirrocco
    I'm building a small application that will crawl sites where the content is growing (like on stackoverflow) the difference is that the content once created is rarely modified. Now , in the first pass I crawl all the pages in the site. But next, the paged content of that site - I don't want to re-crawl all of it , just the latest additions. So if the site has 500 pages, on the second pass if the site has 501 pages then I would only crawl the first and second pages. Would this be a good way to handle the situation ? In the end, the crawled content will end up in lucene - creating a custom search engine. So, I would like to avoid crawling multiple times the same content. Any better ideas ? EDIT : Let's say the site has a page : Results that will be accessed like so : Results?page=1 , Results?page=2 ...etc I guess that keeping a track of how many pages there were at the last crawl and just crawl the difference would be enough. ( maybe using a hash of each result on the page - if I start running into the same hashes - I should stop)

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  • Color banding only on Android 4.0+

    - by threeshinyapples
    On emulators running Android 4.0 or 4.0.3, I am seeing horrible colour banding which I can't seem to get rid of. On every other Android version I have tested, gradients look smooth. I have a SurfaceView which is configured as RGBX_8888, and the banding is not present in the rendered canvas. If I manually dither the image by overlaying a noise pattern at the end of rendering I can make the gradients smooth again, though obviously at a cost to performance which I'd rather avoid. So the banding is being introduced later. I can only assume that, on 4.0+, my SurfaceView is being quantized to a lower bit-depth at some point between it being drawn and being displayed, and I can see from a screen capture that gradients are stepping 8 values at a time in each channel, suggesting a quantization to 555 (not 565). I added the following to my Activity onCreate function, but it made no difference. getWindow().setFormat(PixelFormat.RGBA_8888); getWindow().addFlags(WindowManager.LayoutParams.FLAG_DITHER); I also tried putting the above in onAttachedToWindow() instead, but there was still no change. (I believe that RGBA_8888 is the default window format anyway for 2.2 and above, so it's little surprise that explicitly setting that format has no effect on 4.0+.) Which leaves the question, if the source is 8888 and the destination is 8888, what is introducing the quantization/banding and why does it only appear on 4.0+? Very puzzling. I wonder if anyone can shed some light?

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  • How to enforce that HTTP client uses conditional requests for updates?

    - by Day
    In a (proper RMM level 3) RESTful HTTP API, I want to enforce the fact that clients should make conditional requests when updating resources, in order to avoid the lost update problem. What would be an appropriate response to return to clients that incorrectly attempt unconditional PUT requests? I note that the (abandoned?) mod_atom returns a 405 Method Not Allowed with an Allow header set to GET, HEAD (view source) when an unconditional update is attempted. This seems slightly misleading - to me this implies that PUT is never a valid method to attempt on the resource. Perhaps the response just needs to have an entity body explaining that If-Match or If-Unmodified-Since must be used to make the PUT request conditional in which case it would be allowed? Or perhaps a 400 Bad Request with a suitable explanation in the entity body would be a better solution? But again, this doesn't feel quite right because it's using a 400 response for a violation of application specific semantics when RFC 2616 says (my emphasis): The request could not be understood by the server due to malformed syntax. But than again, I think that using 400 Bad Request for application specific semantics is becoming a widely accepted pragmatic solution (citation needed!), and I'm just being overly pedantic.

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  • C++, inject additional data in a method

    - by justik
    I am adding the new modul in some large library. All methods here are implemented as static. Let mi briefly describe the simplified model: typedef std::vector<double> TData; double test ( const TData &arg ) { return arg ( 0 ) * sin ( arg ( 1 ) + ...;} double ( * p_test ) ( const TData> &arg) = &test; class A { public: static T f1 (TData &input) { .... //some computations B::f2 (p_test); } }; Inside f1() some computations are perfomed and a static method B::f2 is called. The f2 method is implemented by another author and represents some simulation algorithm (example here is siplified). class B { public: static double f2 (double ( * p_test ) ( const TData &arg ) ) { //difficult algorithm working p_test many times double res = p_test(arg); } }; The f2 method has a pointer to some weight function (here p_test). But in my case some additional parameters computed in f1 for test() methods are required double test ( const TData &arg, const TData &arg2, char *arg3.... ) { } How to inject these parameters into test() (and so to f2) to avoid changing the source code of the f2 methods (that is not trivial), redesign of the library and without dirty hacks :-) ? The most simple step is to override f2 static double f2 (double ( * p_test ) ( const TData &arg ), const TData &arg2, char *arg3.... ) But what to do later? Consider, that methods are static, so there will be problems with objects. Thanks for your help.

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  • How to synchronize two (or n) replication processes for SQL Server databases?

    - by Yauheni Sivukha
    There are two master databases and two read-only copies updated by standard transactional replication. It is needed to map some entity from both read-only databases, lets say that A databases contains orders and B databases contains lines. The problem is that replication to one database can lag behind replication of second database, and at the moment of mapping R-databases will have inconsistent data. For example. We stored 2 orders with lines at 19:00 and 19:03. Mapping process started at 19:05, but to the moment of mapping A database replication processed all changes up to 19:03, but B database replication processed only changes up to 19:00. After mapping we will have order entity with order as of 19:03 and lines as of 19:00. The troubles are guaranteed:) In my particular case both databases have temporal model, so it is possible to fetch data for every time slice, but the problem is to identify time of latest replication. Question: How to synchronize replication processes for several databases to avoid situation described above? Or, in other words, how to compare last time of replication in each database? UPD: The only way I see to synchronize is to continuously write timestamps into service tables in each database and to check these timestamps on replicated servers. Is that acceptable solution?

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  • Persisting object changes from child form to parent form based on button press.

    - by Shyran
    I have created a form that is used for both adding and editing a custom object. Which mode the form takes is provided by an enum value passed from the calling code. I also pass in an object of the custom type. All of my controls at data bound to the specific properties of the custom object. When the form is in Add mode, this works great as when the controls are updated with data, the underlying object is as well. However, in Edit mode, I keep two variables of the custom object supplied by the calling code, the original, and a temporary one made through deep copying. The controls are then bound to the temporary copy, this makes it easy to discard the changes if the user clicks the Cancel button. What I want to know is how to persist those changes back to the original object if the user clicks the OK button, since there is now a disconnect because of the deep copying. I am trying to avoid implementing a internal property on the Add/Edit form if I can. Below is an example of my code: public AddEditCustomerDialog(Customer customer, DialogMode mode) { InitializeComponent(); InitializeCustomer(customer, mode); } private void InitializeCustomer(Customer customer, DialogMode mode) { this.customer = customer; if (mode == DialogMode.Edit) { this.Text = "Edit Customer"; this.tempCustomer = ObjectCopyHelper.DeepCopy(this.customer); this.customerListBindingSource.DataSource = this.tempCustomer; this.phoneListBindingSource.DataSource = this.tempCustomer.PhoneList; } else { this.customerListBindingSource.DataSource = this.customer; this.phoneListBindingSource.DataSource = this.customer.PhoneList; } }

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  • Using a single texture image unit with multiple sampler uniforms

    - by bcrist
    I am writing a batching system which tracks currently bound textures in order to avoid unnecessary glBindTexture() calls. I'm not sure if I need to keep track of which textures have already been used by a particular batch so that if a texture is used twice, it will be bound to a different TIU for the second sampler which requires it. Is it acceptable for an OpenGL application to use the same texture image unit for multiple samplers within the same shader stage? What about samplers in different shader stages? For example: Fragment shader: ... uniform sampler2D samp1; uniform sampler2D samp2; void main() { ... } Main program: ... glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, tex_id); glUniform1i(samp1_location, 0); glUniform1i(samp2_location, 0); ... I don't see any reason why this shouldn't work, but what about if the shader program also included a vertex shader like this: Vertex shader: ... uniform sampler2D samp1; void main() { ... } In this case, OpenGL is supposed to treat both instances of samp1 as the same variable, and exposes a single location for them. Therefore, the same texture unit is being used in the vertex and fragment shaders. I have read that using the same texture in two different shader stages counts doubly against GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS but this would seem to contradict that. In a quick test on my hardware (HD 6870), all of the following scenarios worked as expected: 1 TIU used for 2 sampler uniforms in same shader stage 1 TIU used for 1 sampler uniform which is used in 2 shader stages 1 TIU used for 2 sampler uniforms, each occurring in a different stage. However, I don't know if this is behavior that I should expect on all hardware/drivers, or if there are performance implications.

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