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  • Can the lock function be used to implement thread-safe enumeration?

    - by Daniel
    I'm working on a thread-safe collection that uses Dictionary as a backing store. In C# you can do the following: private IEnumerable<KeyValuePair<K, V>> Enumerate() { if (_synchronize) { lock (_locker) { foreach (var entry in _dict) yield return entry; } } else { foreach (var entry in _dict) yield return entry; } } The only way I've found to do this in F# is using Monitor, e.g.: let enumerate() = if synchronize then seq { System.Threading.Monitor.Enter(locker) try for entry in dict -> entry finally System.Threading.Monitor.Exit(locker) } else seq { for entry in dict -> entry } Can this be done using the lock function? Or, is there a better way to do this in general? I don't think returning a copy of the collection for iteration will work because I need absolute synchronization.

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  • django threadedcomments

    - by Patrick
    Hi folks, I would like to setup a comment systems on my site, using django threadedcomments, and I follow all the steps in the Tutorial, however, I get the following error: No module named newforms.util I am not sure what causing this issue, here is my configuration: #settings.py INSTALLED_APPS = ( 'django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.sites', 'myproject.myapp', 'threadedcomments', ) #urls.py from django.conf import settings from django.conf.urls.defaults import * from django.contrib import admin admin.autodiscover() urlpatterns = patterns('', (r'^admin/', include(admin.site.urls)), (r'^threadedcomments/', include('threadedcomments.urls')), ) Please let me know if there is another better choice for commenting, as long as the comment system is flexible and able to do lot of customization, as well as threadedcomment, of coz, integrating with Rating, I am happy to use the other one. Thanks guys.

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  • In which layer should I join 2 entities together?

    - by William
    I use Spring MVC and a regular JDBC. I've just learned that I should separate business process into layers which are presentation layer, controller layer, service layer, and repository/DAO layer. Now suppose that I have an Entity called Person that can have multiple Jobs. Job itself is another entity which have its own properties. From what I gathered, the repository layer only manages one entity. Now I have one entity that contains another entity. Where do I "join" them? The service layer? Suppose I want to get a person whose job isn't known yet (lazy loading). But the system might ask what the job of that particular person is later on. What is the role of each layer in this case? Please let me know if I need to add any detail into this question.

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  • insert data into several tables

    - by csetzkorn
    Let us say I have a table (everything is very much simplified): create table OriginalData ( bla char(10) not null ) And I would like to insert its data (set based!) into two tables which model inheritance create table Statements ( Id int IDENTITY NOT NULL, ProposalDateTime DATETIME null ) create table Items ( StatementFk INT not null, ItemName NVARCHAR(255) null, primary key (StatementFk) ) Statements is the parent table and Items is the child table. I have no problem doing this with one row which involves the use of IDENT_CURRENT but I have no idea how to do this set based (i.e. enter several rows into both tables). Thanks. Best wishes, Christian

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  • What's the preferred way to use helper methods in Ruby?

    - by DR
    Disclaimer: Although I'm asking in context of a Rails application, I'm not talking about Rails helpers (i.e. view helpers) Let's say I have a helper method/function: def dispatch_job(job = {}) #Do something end Now I want to use this from several places (mostly controllers, but also a few BackgrounDRb workers) What's the preferred way to do this? I can think of two possibilities: 1. Use a class and make the helper a static method: class MyHelper def self.dispatch_job(job = {}) end end class MyWorker def run MyHelper.dispatch_job(...) end end 2. Use a module and include the method into whatever class I need this functionality module MyHelper def self.dispatch_job(job = {}) end end class MyWorker include MyHelper def run dispatch_job(...) end end 3. Other possibilities I don't know yet ... The first one is more Java-like, but I'm not sure if the second one is really an appropriate use of Ruby's modules.

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  • Function template accepting nothing less than a bidirectional iterator or a pointer

    - by san
    I need a function template that accepts two iterators that could be pointers. If the two arguments are random_access iterators I want the return type to be an object of std::iterator<random_access_iterator_tag, ...> type else a std::iterator<bidirectional_iterator_tag, ...> type. I also want the code to refuse compilation if the arguments are neither a bidirectional iterator, nor a pointer. I cannot have dependency on third party libraries e.g. Boost Could you help me with the signature of this function so that it accepts bidirectional iterators as well as pointers, but not say input_iterator, output_iterator, forward_iterators. One partial solution I can think of is the following template<class T> T foo( T iter1, T iter2) { const T tmp1 = reverse_iterator<T>(iter1); const T tmp2 = reverse_iterator<T>(iter2); // do something } The idea is that if it is not bidirectional the compiler will not let me construct a reverse_iterator from it.

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  • Where can I learn advanced Haskell?

    - by FredOverflow
    In a comment to one of my answers, SO user sdcwc essentially pointed out that the following code: comb 0 = [[]] comb n = let rest = comb (n-1) in map ('0':) rest ++ map ('1':) rest could be replaced by: comb n = replicateM n "01" which had me completely stunned. Now I am looking for a tutorial, book or PDF that teaches these advanced concepts. I am not looking for a "what's a monad" tutorial aimed at beginners or online references explaining the type of replicateM. I want to learn how to think in monads and use them effectively, monadic "patterns" if you will.

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  • static constants return instance of specific class in Flex?

    - by Sang
    So here's what I mean. Let's say I have a class ErrorMessages which holds all my error messages as static constants. So I could access them like ErrorMessages.PASSWORD_INVALID or ErrorMessage.PASSWORD_TOO_SHORT. I want to know if it is possible to have separate classes that hold subset of these constants and access them like ErrorMessages.PASSWORD.INVALID or ErrorMessages.PASSWORD.TOO_SHORT, etc. This way I can more structured static structure and makes it much easier to use autocomplete. I tried few different ways and couldn't figure out if this was possible..

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  • javascript window.close, once again

    - by John Kjøller
    Im sorry if I havent done my research properly, - but couldnt find the answer I needed, so here goes: From my main page I open a new window using mainPlayer = window.open(); This window stays open until user clicks on a mainPlayer.close(); event. (or simply x closes the window) However, the idea is to make it possible to let the player keep playing, while browsing around the rest of the pages. But as soon as the user leaves the page that opened the mainPlayer window, the reference to the mainPlayer window seem to be lost. How do I, from the site's other pages, check if the mainPlayer window is open and close it on a click event? Thx John

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  • Richfaces Calendar Minimum and Maximum Dates

    - by DaUltimateTrooper
    Hello everybody! My problem is making the RichFaces calendar restricting the dates to be allowed to be chosen by the user. Let's say I want to allow only the dates of this month and the dates of the next month to be chosen by the user. I used the preloadDateRangeStart and preloadDateRangeEnd attributes but they did nothing. I created my own CalendarDataModel which uses the preloadDateRangeStart and preloadDateRangeEnd and enables the items but the calendar on the screen allows only the dates of the current month to be selected. Note that the preloadDateRangeStart is today's date and preloadDateRangeEnd is today's date plus 2 months. I am missing something here for sure. Can someone help me please?

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  • Implementing a runtime Look Up Table in C#

    - by Yarok
    Hey all, I'm currently working on a robot interface GUI, using C#. The robot has two sensors, and two powered wheels. I need to let the user the option to load a Look Up Table (LUT) during runtime, one for each sensor, that will tell the robot what to do according to the sensor's reading. I think the best way to do it is using a .csv file, formatted like so: index , right wheel order, left wheel order the index is an int between 0-1023 and is actually the sensor's reading. the orders for the right and left wheel are integers, between -500 - 500. Example - left sensor's readings: 1,10,20 meaning: sensor reads 1 -- left wheel 10 rpm right wheel 20 rpm So my question is this: what is the best way to implement it? using a dataset?(if so, how?) using an array? (if so, how do I load it during runtime?) Any help would be much appreciated, Yarok

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  • Properties.Settings.Default.Default.Save() does not work

    - by Akshay
    I have created code in WPF to let the window remember its last location like this: private void Window_Loaded(object sender, RoutedEventArgs e) { try { Rect storedLoc = Properties.Settings.Default.WindowSavedLocation; this.Top = storedLoc.Top; this.Left = storedLoc.Left; } catch { MessageBox.Show("No settings stored !"); } } private void Window_Closed(object sender, EventArgs e) { Properties.Settings.Default.WindowSavedLocation = RestoreBounds; Properties.Settings.Default.Save(); } When I build the application I can see that the app.exe.config file has the setting WindowSavedLocation but it just does not save and throws no exception. Everytime I run the application, it says "No settings stored !". It's scope is user.

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  • Efficient bitshifting an array of int?

    - by nn
    Hi, To be on the same page, let's assume sizeof(int)=4 and sizeof(long)=8. Given an array of integers, what would be an efficient method to bitshift the array to either the left or right? I am contemplating an auxiliary variable such as a long, that will compute the bitshift for the first pair of elements (index 0 and 1) and set the first element (0). Continuing in this fashion the bitshift for elements (index 1 and 2) will be computer, and then index 1 will be set. I think this is actually a fairly efficient method, but there are drawbacks. I cannot bitshift greater than 32 bits. I think using multiple auxiliary variables would work, but I'm envisioning recursion somewhere along the line.

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  • Use different Solr Similarity algo for every search

    - by snickernet
    Hi Guys, Is possible in Solr 1.4 to specify which similarity class to use for every search within a single index? Let's say, I got 2 type of search (keyword and brand). For keyword search, I want to use the DefaultSimilarity class. But, for brand search, I want to use my CustomSimilarity class. I've been modifying the schema.xml to specify a single similarity class to use. But, I came to this requirement that I have to use 2 different similarity classes. I'll be glad to here your thoughts on this. Thanks in advance.

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  • Using Visual Studio to create web application in Sharepoint 2010

    - by bryan0010
    Hello, I am looking for pointers, examples, etc. to create a basic application in sharepoint 2010 using visual studio. The application would show a list on page 1 (driven by linq entities). When you click a row, it shows a details page. I've gone through the tutorials but could not find a basic crud-like example as explained above. Any help would be greatly appreciated. If I missed something in one of the tutorials, please let me know. To summarize, in a very generic way; I am looking for information on how to display two web application pages and have the user click a link or control to move through pages. Regards, Bryan

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  • PHP explode and set to empty string the missing pieces

    - by Marco Demaio
    What's the best way to accomplish the following. I have strings in this format: $s1 = "name1|type1"; //(pipe is the separator) $s2 = "name2|type2"; $s3 = "name3"; //(in some of them type can be missing) Let's assume namen/typen are strings and they can not contain a pipe. Since I need to exctract the name/type separetly, I do: $temp = explode($s1, '|'); $name = $temp[0]; $type = ( isset($temp[1]) ? $temp[1] : '' ); Is there an easier (smarter whatever faster) way to do this without having to do isset($temp[1]) or count($temp). Thanks!

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  • Mapping over multiple Seq in Scala

    - by bsdfish
    Suppose I have val foo : Seq[Double] = ... val bar : Seq[Double] = ... and I wish to produce a seq where the baz(i) = foo(i) + bar(i). One way I can think of to do this is val baz : Seq[Double] = (foo.toList zip bar.toList) map ((f: Double, b : Double) => f+b) However, this feels both ugly and inefficient -- I have to convert both seqs to lists (which explodes with lazy lists), create this temporary list of tuples, only to map over it and let it be GCed. Maybe streams solve the lazy problem, but in any case, this feels like unnecessarily ugly. In lisp, the map function would map over multiple sequences. I would write (mapcar (lambda (f b) (+ f b)) foo bar) And no temporary lists would get created anywhere. Is there a map-over-multiple-lists function in Scala, or is zip combined with destructuring really the 'right' way to do this?

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  • Source control issue with deploying versions

    - by Bonefisher
    Hi all, we have this discussion about how to deploy to production revisions that are UAT closed without revisions with UAT not-closed status. We are using SVN and we figured out that we are not able to just take revisions without prior-revisions on the same file made. Let me explain it on this example: we have 3 revisions made on same file: r1: UAT closed (ready to deploy) r2: UAT not-closed (not ready) r3: UAT closed (ready to deploy) now I want to deploy only my changes for which the UAT is closed (e.g. r1 and r3). In SVN this is not possible because r3 contains also r2 changes.. How do you made this to work? Maybe branching? Or just take r1 and wait until r2 is UAT closed? thanks

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  • Convert search from SQL Server to MySQL

    - by HAJJAJ
    hi, everyone. i need to convert this one from SQL Server into MySQL IF IsNull(@SearchText, '') <> '' BEGIN SET @SearchText = '%' + @SearchText + '%' SELECT NewsID,DeptID,DeptName,Title,Details ,NewsDate,img FROM @tbSearchtextTb WHERE IsNull(Title,'')+IsNull(Details,'') LIKE @SearchText END this code will search fro my search word in this columns: Title, Details. i tried to convert this line but i had lots of errors: these are my unsuccessful attempts IF ISNULL(SearchText,'') <> '' THEN SELECT CatID,CatTitle,CatDescription,CatTitleAr,CatDescriptionAr,PictureID,Published,DisplayOrder,CreatedOn FROM tmp WHERE CatTitle + CatDescription + CatTitleAr + CatDescriptionAr LIKE $SearchText; and this one IF $SearchText IS NOT NULL THEN SELECT CatID,CatTitle,CatDescription,CatTitleAr,CatDescriptionAr,PictureID,Published,DisplayOrder,CreatedOn FROM tmp WHERE ISNULL(CatTitle,'') +ISNULL(CatDescription ,'') +ISNULL(CatTitleAr ,'') +ISNULL(CatDescriptionAr,'') LIKE $SearchText; and many many other ways but i could not find any. so if you know please let me know, thanks and best regards.

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  • Maximum number of files in one ext3 directory while still getting acceptable performance?

    - by knorv
    I have an application writing to an ext3 directory which over time has grown to roughly three million files. Needless to say, reading the file listing of this directory is unbearably slow. I don't blame ext3. The proper solution would have been to let the application code write to sub-directories such as ./a/b/c/abc.ext rather than using only ./abc.ext. I'm changing to such a sub-directory structure and my question is simply: roughly how many files should I expect to store in one ext3 directory while still getting acceptable performance? What's your experience? Or in other words; assuming that I need to store three million files in the structure, how many levels deep should the ./a/b/c/abc.ext structure be? Obviously this is a question that cannot be answered exactly, but I'm looking for a ball park estimate.

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  • ToList()-- Does it Create a New List?

    - by Ngu Soon Hui
    Let's say I have a class public class MyObject { public int SimpleInt{get;set;} } And I have a List<MyObject>, and I ToList() it and then change one of the SimpleInt, will my change be propagated back to the original list. In other words, what would be the output of the following method? public void RunChangeList() { var objs = new List<MyObject>(){new MyObject(){SimpleInt=0}}; var whatInt = ChangeToList(objs ); } public int ChangeToList(List<MyObject> objects) { var objectList = objects.ToList(); objectList[0].SimpleInt=5; return objects[0].SimpleInt; } Why? P/S: I'm sorry if it seems obvious to find out. But I don't have compiler with me now...

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  • Reading TCP Sequence Number Before Sending a Packet

    - by Sadeq Dousti
    I'm writing a C/C++ client-server program under Linux. Assume a message m is to be sent from the client to the server. Is it possible for the client to read the TCP sequence number of the packet which will carry m, before sending m? In fact, I'd like to append this sequence number to m, and send the resulting packet. (Well, things are more complicated, but let's keep it that simple. In fact, I'd like to apply authentication info to this sequence number, and then append it to m.) Moreover, is it possible for the server to read the TCP sequence number of the packet carrying m?

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  • checkbox selected value is lost after coming back to the pagei.e., viewstate value is lost with use

    - by M.Vijay bhasker
    In the left navigation i have a series of check boxes and a grid view in the page body.Grid view results changes based on the check box selection,whenever i click on the links in grid view it goes to the second page and there is a link on the page which takes me back to the first page,but the check box selected value is maintained for the first time only and if we repeat the same process for the second time and i see that the first time selection of the check box is maintained.Here the grid view is placed in update panel and the check box in the left is called using .... AsyncPostBackTrigger ControlID="cphLeftNavigation". I've tried removing the above code referring the cphLeftNavigation and i see the results are coming up correctly and the last selected check box value is being maintained correctly and i want the same functionality to be implemented with/without update panel. Can anyone let me know,what exactly should i change to implement the above mentioned functionality.

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  • add extra data to response object to render in template

    - by mp0int
    I ned to write a code sniplet that enables to disable connection to some parts of a site. Admin and the mainpage will be displayable, but user section (which uses ajax) will be displayed, but can not be used (vith a transparent div set over the page). Also there is a few pages which will be disabled. my logic is that, i write a middleware, def process_request(self, request): if ayar.tonline_kapali: url_parcalari = request.path.split('/') if url_parcalari[0] not in settings.BAGIMSIZ_URLLER: if not request.is_ajax(): return render_to_response('bakim_modu.html') else: return None that code let me to display a "site closed" message for the urls not in BAGIMSIZ_URLLER (which contains urls that will be accessible) But i do not figure out how can i solve the problem about ajax pages... i need to set a header or something to the response and need to check it in the template.

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  • What advantages can I get from learning C++ if I'm mainly a C# Programmer?

    - by Sergio Tapia
    Hello, Recently I've started to notice a lot of smirks and generally rude comments whenever I mention C#. Everyone I talk to either says learn Python or learn C++. Python is a nice language, I get it. But I don't find much use for it right now (for my use cases), and C++ I heard is a faster language (not sure). So my question is this, what advantage can I get from learning C++ (besides the knowledge and expansion of my horizons), when I mainly program in C#. If anyone can make a legitimate claim, I'll for sure look into learning the language because let's face it, I trust you guys. Thanks so much for all the help.

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