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  • Ruby/RoR: calling original method via super()?

    - by fearless_fool
    In a RoR app, I want to specialize ActiveRecord's update_attributes() method in one of my models, extracting some of the attributes for special handling and passing the rest of them to the original update_attributes() method. The details: class Premise < ActiveRecord::Base ... def update_attributes(attrs) attrs.each_pair do |key, val| unless has_attribute?(key) do_special_processing(key, val) attrs.delete(key) end end # use original update_attributes() to process non-special pairs super.update_attributes(attrs) end ... end The call to super.update_attributes(attr) raises an error: undefined method `update_attributes' for true:TrueClass ... which makes me suspect I really don't understand the super keyword in Ruby. What am I missing? Specifically, how do I call the original update_attributes() method?

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  • c# Generic overloaded method dispatching ambiguous

    - by sebgod
    Hello, I just hit a situation where a method dispatch was ambiguous and wondered if anyone could explain on what basis the compiler (.NET 4.0.30319) chooses what overload to call interface IfaceA { } interface IfaceB<T> { void Add(IfaceA a); T Add(T t); } class ConcreteA : IfaceA { } class abstract BaseClassB<T> : IfaceB<T> { public virtual T Add(T t) { ... } public virtual void Add(IfaceA a) { ... } } class ConcreteB : BaseClassB<IfaceA> { // does not override one of the relevant methods } void code() { var concreteB = new ConcreteB(); // it will call void Add(IfaceA a) concreteB.Add(new ConcreteA()); } In any case, why does the compiler not warn me or even why does it compile? Thank you very much for any answers.

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  • JTA Transaction: What happens if an exception happens but rollback is not called on the transaction?

    - by kellyfj
    We have some third party code wherein they do the following 1) Create a User Transaction e.g. txn = (UserTransaction)ctx.lookup( "UserTransaction" ); txn.begin( ); 2) Do some work persisting to the database (via JPA) to a MySQL database 3) txn.commit() They have Exception blocks but NONE of them call txn.rollback. Good coding practice says they NEED to call rollback if an exception occurs but my question is If the txn is not commited, and an exception occurs what is the negative effect of them NOT calling rollback?

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  • casting BSTR as char* in a dll; different results depnding on VB/C# caller.

    - by Toby Wilson
    I have a dll function that takes BSTR parameters. These are casted as char* before being used for other things. When the dll is called from VB code this works fine. However, when it is called from C# code, only the first character is pointed to. Both of these are excel addIns for Pre-2007 and 2007+ versions of Office, which call into a faster C++ AddIn. They actually call it directly, not through Excel. The VB function declaration looks like this: Private Declare Function Test Lib "ExcelAddIn.xll" (ByVal param As String) As String The C# function declaration looks like this: [DllImport("ExcelAddIn.xll", CharSet=CharSet.Ansi)] [return:MarshalAs(UnmanagedType.BStr)] private static extern string Test([MarshalAs(UnmanagedType.BStr)] string param); When debugging the dll and watching the input BSTR values, they appear to be correct from both; just the C# one only casts the first character. Charset=CharSet.Unicode makes no difference. Any ideas anyone?

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  • Jsonp cross-domain ajax

    - by Guillaume le Floch
    I'm working on an application which use ajax call to get html from the server. When I run it on the server, everything works fine. But when I'm running on a localhost, I've a 'Access-Control-Allow-Origin' error. I looked arround and it seems like using jsonp could be the solution. So, my ajax call looks like that: $.ajax({ url: url, dataType: 'jsonp', crossDomain: true, type: 'GET', success: function(data){ // should put the data in a div }, error: function(){ //do some stuff with errors } }); I get html from the server, but I always have this error: Uncaught SyntaxError: Unexpected token < Is there a way to wrap the jsonp response in html? Thanks!

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  • Why is my form triggering the wrong controller action?

    - by COCoach
    This form has multiple submit buttons, when clicked, it calls a simple JavaScript function to change the value of a hidden input (function is called "setHidden". This worked before, after some other not relevant code, it has ceased working. Essentially, the action it is supposed to call is never called, instead it seems to default back to a previous URL. The Form: <form action="/League/RemoveOwner" method="post"> <input type="hidden" value="1007" name="lid"/> <input type="hidden" value="0" id="index" name="index"/> <input type="image" src="../../Resources/Images/Delete.png" height="12" alt="Remove Owner" title="Remove Owner" onclick="setHidden('index', '1031')"/></a> coach<br /> </form> The Controller: [HttpPost] public ActionResult RemoveOwner(int id, string index) { //yada return PartialView(); } When clicking the image, it should call the remove owner controller, instead it calls the "View" controller: public ActionResult View(int id) { //yada return View(); }

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  • CakePHP: Ajax view problem (nothing in the view showing)

    - by Adim
    I created a function in my controller called addToPlaylist($songName). I wanted to add these song names to an array and then a session variable using an Ajax call. The first time i did this i got an error saying i do not have a template file to display in the chosen div ("add_to_playlist.ctp was missing"). I created this file and everything seemed to be working correctly. Basically I went to bed woke up and it is broken (it is possible I changed something before I went to bed). The problem now is that it does not show anything when i click the ajax link. when i click on the ajax link it seems to call the function but nothing displays in the view (except debug info) even when i delete the view (add_to_playlist.ctp) i get no errors, I just see debug info now.

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  • Ruby execute code in class getting inherited to

    - by AdamB
    I'm trying to be able to have a global exception capture where I can add extra information when an error happens. I have two classes, "crawler" and "amazon". What I want to do is be able to call "crawl", execute a function in amazon, and use the exception handling in the crawl function. Here are the two classes I have: require 'mechanize' class Crawler Mechanize.html_parser = Nokogiri::HTML def initialize @agent = Mechanize.new end def crawl puts "crawling" begin #execute code in Amazon class here? rescue Exception => e puts "Exception: #{e.message}" puts "On url: #{@current_url}" puts e.backtrace end end def get(url) @current_url = url @agent.get(url) end end class Amazon < Crawler #some code with errors def stuff page = get("http://www.amazon.com") puts page.parser.xpath("//asldkfjasdlkj").first['href'] end end a = Amazon.new a.crawl Is there a way I can call "stuff" inside of "crawl" so I can use that exception handling over the entire stuff function? Is there a better way to accomplish this?

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  • Maven Ant BuildException with maven-antrun-plugin ... unable to find javac compiler

    - by robsbobs
    Im trying to make Maven call an ANT build for some legacy code. the ant build builds correctly through ant however when i call it using the maven ant plugin it fails with the following error: [ ERROR] Failed to execute goal org.apache.maven.plugins:maven-antrun-plugin:1.6:run (default) on project CoreServices: An Ant BuildException has occured: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:158: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:62: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:33: The following error occurred while executing this line: [ERROR] C:\dev\projects\ods\build.xml:41: Unable to find a javac compiler; [ERROR] com.sun.tools.javac.Main is not on the classpath. [ERROR] Perhaps JAVA_HOME does not point to the JDK. [ERROR] It is currently set to "C:\bea\jdk150_11\jre" My javac exists at C:\bea\jdk150_11\bin and this works for all other things. Im not sure where Maven is getting this version of JAVA_HOME. JAVA_HOME in windows envionrmental variables is set to C:\bea\jdk150_11\ as it should be. The Maven code that im using to call the build.xml is <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-antrun-plugin</artifactId> <version>1.6</version> <executions> <execution> <phase>install</phase> <configuration> <target> <ant antfile="../build/build.xml" target="deliver" > </ant> </target> </configuration> <goals> <goal>run</goal> </goals> </execution> </executions> </plugin> </plugins> </build>

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  • Ruby and Rails Async

    - by Edijs Petersons
    I need to perform long-running operation in ruby/rails asynchronously. Googling around one of the options I find is Sidekiq. class WeeklyReportWorker include Sidekiq::Worker def perform(user, product, year = Time.now.year, week = Date.today.cweek) report = WeeklyReport.build(user, product, year, week) report.save end end # call WeeklyReportWorker.perform_async('user', 'product') Everything works great! But there is a problem. If I keep calling this async method every few seconds, but the actual time heavy operation performs is one minute things won't work. Let me put it in example. 5.times { WeeklyReportWorker.perform_async('user', 'product') } Now my heavy operation will be performed 5 times. Optimally it should have performed only once or twice depending on whether execution of first operaton started before 5th async call was made. Do you have tips how to solve it?

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  • in django am facing url problem.....

    - by dpaksp
    am using django.0.97 version i have model called profile in that i have few fields eg like name ,email...ects and it's backend also ready..i.e database . and all users profile is created...i have given all permission to all users. when i login ,click on profile..i able to see list of all user name thr when i click on it ,it's goin to model page where i can edit the user profile..instead of that i want to navigate to a template when i can display the user details ,i have set the URl for it so that when url of that type request comes it should call a view from view it will call my template to display user details,.....the problem is it's not calling my view.... i think my problem is brief....if any information still required ?? pls ask me....and help me

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  • Compiling SQLite into programs that run on Symbian 9.1 and above?

    - by Jared
    How can I use SQLite C API’s on any device running Symbian OS 9.1 or above? While it appears that 9.4 comes with SQLite built in prior versions do not. Looking at http://sourceforge.net/projects/sqlites60/ it appears that sQLite has been ported to older Symbian releases. The only problem is this code assumes you want to use SQLite with .net when I want to compile it into a .sis file and call the C API’s. Ideally I’d compile a Symbian equivalent of amalgamation.c and call the sQLite functions directly but am not sure if this is possible.

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  • lazyinializationexception with transactional annotation in messageconvert

    - by Karl
    Hi, I have a Rest-Service exposed through spring-mvc. I have a particular method which is correctly mapped and called through a http-call. My spring application contains the hibernatetransactionmanager and transactions are configured through @Transactional-annotations. I annotated the method with @Transactional. @Transactional(readOnly = true) @Override @RequestMapping(value = "/start", method = RequestMethod.GET) @ResponseBody public List start(....) Whenever I call the http-method I get org.hibernate.LazyInitializationException from my org.springframework.http.converter.json.MappingJacksonHttpMessageConverter which is bound in my application context. Is the @Transactional annotation valid for the MessageConverter as well?

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  • Why is 'using' improving C# performances

    - by Wernight
    It seems that in most cases the C# compiler could call Dispose() automatically. Like most cases of the using pattern look like: public void SomeMethod() { ... using (var foo = new Foo()) { ... } // Foo isn't use after here (obviously). ... } Since foo isn't used (that's a very simple detection) and since its not provided as argument to another method (that's a supposition that applies to many use cases and can be extended), the compiler could automatically call Dispose() without the developper requiring to do it. This means that in most cases the using is pretty useless if the compiler does some smart job. IDisposable seem low level enough to me to be taken in account by a compiler. Now why isn't this done? Wouldn't that improve the performances (if the developpers are... dirty).

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  • Passing value from :locals to link_remote_to

    - by Teef L
    In my edit.haml file, I have =render :partial => 'old_question_tags', :locals => {:current_question => @question.id}. I'd like to pass the value in :current_question to a link_to_remote call in _old_question_tags.haml: #{link_to_remote image_tag('red-x.png', {:alt => "Remove #{t.name} tag"}), :url => {:action => 'remove_old_tag_from_question', :tag_remove => t.id, :current_question => current_question}} But I get this error on the link_to_remote line: ActionView::TemplateError (undefined local variable or method `current_question' for #<ActionView::Base:0xdb2fec8>) In _old_question_tags.haml, if I just print current_question (using =current_question), it prints the number without any problems. How do I properly pass that value to the partial so that I can pass it to the link_to_remote call?

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  • waiting for 2 different events in a single thread

    - by João Portela
    component A (in C++) - is blocked waiting for alarm signals (not relevant) and IO signals (1 udp socket). has one handler for each of these. component B (java) - has to receive the same information the component A udp socket receives. periodicaly gives instructions that should be sent through component A udp socket. How to join both components? it is strongly desirable that: the changes to attach component B to component A are minimal (its not my code and it is not very pleasent to mess with). the time taken by the new operations (usually communicating with component B) interfere very little with the usual processing time of component A - this means that if the operations are going to take a "some" time I would rather use a thread or something to do them. note: since component A receives udp packets more frequently that it has component B instructions to forward, if necessary, it can only forward the instructions (when available) from the IO handler. my initial ideia was to develop a component C (in C++) that would sit inside the component A code (is this called an adapter?) that when instanciated starts the java process and makes the necessary connections (that not so little overhead in the initialization is not a problem). It would have 2 stacks, one for the data to give component B (lets call it Bstack) and for the data to give component A (lets call it Astack). It would sit on its thread (lets call it new-thread) waiting for data to be available in Bstack to send it over udp, and listen on the udp socket to put data on the Astack. This means that the changes to component A are only: when it receives a new UDP packet put it on the Bstack, and if there is something on the Astack sent it over its UDP socket (I decided for this because this socket would only be used in the main thread). One of the problems is that I don't know how to wait for both of these events at the same time using only one thread. so my questions are: Do I really need to use the main thread to send the data over component A socket or can I do it from the new-thread? (I think the answer is no, but I'm not sure about race conditions on sockets) how to I wait for both events? boost::condition_variable or something similar seems the solution in the case of the stack and boost::asio::io_service io_service.run() seems like the thing to use for the socket. Is there any other alternative solution for this problem that I'm not aware of? Thanks for reading this long text but I really wanted you to understand the problem.

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  • Custom setter methods in Core-Data

    - by andrewebling
    I need to write a custom setter method for a field (we'll call it foo) in my subclass of NSManagedObject. foo is defined in the data model and Xcode has autogenerated @property and @dynamic fields in the .h and .m files respectively. If I write my setter like this: - (void)setFoo: (NSObject *)inFoo { [super setFoo: inFoo]; [self updateStuff]; } then I get a compiler warning on the call to super. Alternatively, if I do this: - (void)setFoo: (NSObject *)inFoo { [super setValue: inFoo forKey: inFoo]; [self updateStuff]; } then I end up in an infinite loop. So what's the correct approach to write a custom setter for a subclass of NSManagedObject?

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  • Saving a 'Date' using DataMapper on AppEngine+JRuby

    - by Ryan Montgomery
    I have a a model as follows: class Total include DataMapper::Resource property :id, Serial property :amount, Float, :default => 0.00 property :day, Date belongs_to :calendar end I am trying to select a specific Total from the data-store. class Calendar include DataMapper::Resource property :id, Serial property :name, String has n, :totals def get_total_for(date) return Total.first(:day => date, :calendar => self) end end When I call get_total_for(DateTime.now) I receive the following error on the call to the data-store. java.lang.IllegalArgumentException: day: org.jruby.RubyObject is not a supported property type. Is Date not allowed for usage in AppEngine? Is this a DataMapper issue? I have tried changing the name of the :day property to something else (hoping it was just a name conflict) but it doesn't seem to matter. Thanks for any help you can provide.

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  • Cleanup ActiveRecord field

    - by Beer Brother
    I have model Article it has field title with some text that may contain some "magic" patterns. In some cases i need to process text in title and other cases i don't, but in last case i need to get string w/o that patterns. For example i have title value like "Something **very** interesting" and when i call @article.title i need to get cleaned up string like "Something very interesting", but when i call @article.title_raw i need get original string. The problem also is that i have working application and i cannt do "revolution" but what way to go... -- Excuse me for my bad English.

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  • Rearrange a python list into n lists, by column

    - by Ben R
    Trying to solve this at this hour has gotten my mind into a tail-spin: I want to rearrange a list l into a list of n lists, where n is the number of columns. e.g., l = [1,2,3,4,5,6,7,8] n = 5 ==> [[1,6][2,7][3,8][4][5]] another example: l = [1,2,3,4,5,6,7,8,9,10] n = 4 ==> [[1,5,9],[2,6,10],[3,7][4,8] Can someone please help me out with an algorithm? Feel free to use any python awesomeness that's available; I'm sure theres some cool mechanism that's a good fit for this, i just can't think of it.

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  • Scala methods ending in _=

    - by Alexey Romanov
    I seem to remember Scala treating methods ending in _= specially, so something like this: object X { var x: Int = 0; def y_=(n : Int) { x = n }} X.y = 1 should call X.y_=(1). However, in 2.8.0 RC1, I get an error message: <console>:6: error: value y is not a member of object X X.y = 1 ^ Interestingly, just trying to call the method without parentheses fails as well: scala> X.y_= 1 <console>:1: error: ';' expected but integer literal found. X.y_= 1 ^ Am I misremembering something which does actually exist or did I just invent it out of whole cloth?

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  • ReaderWriterLockSlim question.

    - by Kamarey
    There are lots written about the ReaderWriterLockSlim class which allows multiple read and a single write. All of these (at least that I had found) tell how to use it without much explanation why and how it works. The standard code sample is: lock.EnterUpgradeableReadLock(); try { if (test if write is required) { lock.EnterWriteLock(); try { change the resourse here. } finally { lock.ExitWriteLock(); } } } finally { lock.ExitUpgradeableReadLock(); } The question is: if upgradeable lock permits only a single thread to enter its section, why I should call EnterWriteLock method within? What will happen if I don't? Or what will happen if instead of EnterUpgradeableReadLock I will call EnterWriteLock and will write to a resource without using upgradeable lock at all?

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  • How to tell if running in a linux console versus an ssh session?

    - by Stéphane
    I have an application that needs to behave differently if run directly from the linux console. So if a user connects with SSH to run FooBar, or the user walks over to the console and logs in directly to run FooBar, I want it to do something different. What C API do I need to call to tell the difference between these two scenarios? I was thinking I'd have to look at the "tty/pts" information (such as what I see when I run "ps axf"), but I'm not certain if that is the best solution, nor what API to call to get that information. Hints appreciated. :)

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