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  • Convert enumeration to string

    - by emptyheaded
    I am trying to build a function that converts an item from an enum to its corresponding string. The enums I use are fairly long, so I didn't want to use a switch-case. I found a method using boost::unordered_map very convenient, but I don't know how to make a default return (when there is no item matching the enum). const boost::unordered_map<enum_type, const std::string> enumToString = boost::assign::map_list_of (data_1, "data_1") (data_2, "data_2"); I tried to create an additional function: std::string convert(enum_type entry) { if (enumToString.find(entry)) // not sure what test to place here, return enumToString.at(entry); //because the find method returns an iter else return "invalid_value"; } I even tried something exceedingly wrong: std::string convert(enum_type entry) { try{ return enumToString.at(entry); } catch(...){ return "invalid_value"; } } Result: evil "Debug" runtime error. Can somebody give me a suggestion on how to either 1) find an easier method to convert enum to a string with the same name as the enum item 2) find a way to use already built boost methods to get a default value from a hash map (best option) 3) find what to place in the test to use a function that returns either the pair of the key-value, or a different string if the key is not found in the map. Thank you very much.

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  • C++ socket protocol design issue (ring inclusion)

    - by Martin Lauridsen
    So I have these two classes, mpqs_client and client_protocol. The mpqs_client class handles a Boost socket connection to a server (sending and receiving messages with some specific format. Upon receiving a message, it calls a static method, parse_message(..), in the class client_protocol, and this method should analyse the message received and perform some corresponding action. Given some specific input, the parse_message method needs to send some data back to the server. As mentioned, this happens through the class mpqs_client. So I could, from mpqs_client, pass "this" to parse_message(..) in client_protocol. However, this leads to a two-way association relationship between the two classes. Something which I reckon is not desireable. Also, to implement this, I would need to include the other in each one, and this gives me a terrible pain. I am thinking this is more of a design issue. What is the best solution here? Code is posted below. Class mpqs_client: #include "mpqs_client.h" mpqs_client::mpqs_client(boost::asio::io_service& io_service, tcp::resolver::iterator endpoint_iterator) : io_service_(io_service), socket_(io_service) { ... } ... void mpqs_client::write(const network_message& msg) { io_service_.post(boost::bind(&mpqs_client::do_write, this, msg)); } Class client_protocol: #include "../network_message.hpp" #include "../protocol_consts.h" class client_protocol { public: static void parse_message(network_message& msg, mpqs_sieve **instance_, mpqs_client &client_) { ... switch (type) { case MPQS_DATA: ... break; case POLYNOMIAL_DATA: ... break; default: break; } }

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  • Java constructor using generic types

    - by Beer Me
    I'm having a hard time wrapping my head around Java generic types. Here's a simple piece of code that in my mind should work, but I'm obviously doing something wrong. Eclipse reports this error in BreweryList.java: The method breweryMethod() is undefined for the type <T> The idea is to fill a Vector with instances of objects that are a subclass of the Brewery class, so the invocation would be something like: BreweryList breweryList = new BreweryList(BrewerySubClass.class, list); BreweryList.java package com.beerme.test; import java.util.Vector; public class BreweryList<T extends Brewery> extends Vector<T> { public BreweryList(Class<T> c, Object[] j) { super(); for (int i = 0; i < j.length; i++) { T item = c.newInstance(); // breweryMethod() is an instance method // of Brewery, of which <T> is a subclass (right?) c.breweryMethod(); // "The method breweryMethod() is undefined // for the type <T>" } } } Brewery.java package com.beerme.test; public class Brewery { public Brewery() { super(); } protected void breweryMethod() { } } BrewerySubClass.java package com.beerme.test; public class BrewerySubClass extends Brewery { public BrewerySubClass() { super(); } public void brewerySubClassMethod() { } } I'm sure this is a complete-generics-noob question, but I'm stuck. Thanks for any tips!

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  • Not all symbols of an DLL-exported class is exported (VS9)

    - by mandrake
    I'm building a DLL from a group of static libraries and I'm having a problem where only parts of classes are exported. What I'm doing is declaring all symbols I want to export with a preprocessor definition like: #if defined(MYPROJ_BUILD_DLL) //Build as a DLL # define MY_API __declspec(dllexport) #elif defined(MYPROJ_USE_DLL) //Use as a DLL # define MY_API __declspec(dllimport) #else //Build or use as a static lib # define MY_API #endif For example: class MY_API Foo{ ... } I then build static library with MYPROJ_BUILD_DLL & MYPROJ_USE_DLL undefined causing a static library to be built. In another build I create a DLL from these static libraries. So I define MYPROJ_BUILD_DLL causing all symbols I want to export to be attributed with __declspec(dllexport) (this is done by including all static library headers in the DLL-project source file). Ok, so now to the problem. When I use this new DLL I get unresolved externals because not all symbols of a class is exported. For example in a class like this: class MY_API Foo{ public: Foo(char const* ); int bar(); private: Foo( char const*, char const* ); }; Only Foo::Foo( char const*, char const*); and int Foo::bar(); is exported. How can that be? I can understand if the entire class was missing, due to e.g. I forgot to include the header in the DLL-build. But it's only partial missing. Also, say if Foo::Foo( char const*) was not implemented; then the DLL build would have unresolved external errors. But the build is fine (I also double checked for declarations without implementation). Note: The combined size of the static libraries I'm combining is in the region of 30MB, and the resulting DLL is 1.2MB. I'm using Visual Studio 9.0 (2008) to build everything. And Depends to check for exported symbols.

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  • Populate table fields on query execution

    - by Jason
    I'm trying to build an ASP site that populates a Table based on the results of a selection in a ListBox. In order to do this, I've created a GridView table inside a div element. Currently the default behavior is to show all the items in the specified table in sortable order. However, I'd like to refine this further to allow for display of matches based on the results from the ListBox selection, but am not sure how to execute this. The ListBox fires off a OnSelectionChanged event to the method defined below and the GridView element is defined as <asp:GridView ID="dataListings" runat="server" AllowSorting="True" AutoGenerateColumns="False" DataSourceID="LinqDataSource1" OnDataBinding="ListBox1_SelectedIndexChanged"> protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e) { int itemSelected = selectTopics.SelectedIndex; string[] listing = null; switch (itemSelected)//assign listing the array of course numbers { case 0: break; case 1: listing = arts; break; case 2: listing = currentEvents; break; .... More cases here default: listing = arts; break; } using (OLLIDBDataContext odb = new OLLIDBDataContext()) { var q = from c in odb.tbl_CoursesAndWorkshops where listing.Contains(c.tbl_Course_Description.tbl_CoursesAndWorkshops.course_workshop_number) select c; dataListings.DataSource = q; dataListings.DataBind(); } } However, this method never gets fired. I can see a request being made when changing the selection, but setting a breakpoint at the method declaration does nothing at all. Based on this, setup, I have three related questions What do I need to modify to get the OnSelectionChanged event handler to fire? How can I alter the GridView area to be empty on page load? How do I send the results from the dataListings.DataBind() execution to show in the GridView?

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  • c# template member functions

    - by user3730583
    How can I define a template member function in C# For instance I will fill any collection which supports an Add(...) member function, please check out the sample code below public class CInternalCollection { public static void ExternalCollectionTryOne<T<int>>(ref T<int> ext_col, int para_selection = 0) { foreach (int int_value in m_int_col) { if (int_value > para_selection) ext_col.Add(int_value); } } public static void ExternalCollectionTryTwo<T>(ref T ext_col, int para_selection = 0) { foreach (int int_value in m_int_col) { if (int_value > para_selection) ext_col.Add(int_value); } } static int[] m_int_col = { 0, -1, -3, 5, 7, -8 }; } The ExternalCollectionTryOne<...(...) would be the preferred kind, because the int type can be explicit defined, but results in an error: Type parameter declaration must be an identifier not a type The type or namespace name 'T' could not be found (are you missing a using directive or an assembly reference?) The ExternalCollectionTryTwo<...(...) results in an error: 'T' does not contain a definition for 'Add' and no extension method 'Add' accepting a first argument of type 'T' could be found (are you missing a using directive or an assembly reference?)... I hope the problem is clear – any suggestions? ----------------------------- edit -------------------------- The answers with the interface ICollection<.. without a template member works fine and thanks all for this hint, but I still cannot define successfully a member template(generic) function So a more simpler example ... how can I define this public class CAddCollectionValues { public static void AddInt<T>(ref T number, int selection) { T new_T = new T(); //this line is just an easy demonstration to get a compile error with type T foreach (int i_value in m_int_col) { if (i_value > selection) number += i_value; //again the type T cannot be used } } static int[] m_int_col = { 0, -1, -3, 5, 7, -8 }; }

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  • Error : Number of Rows In Section in UITableView in iPhone SDK

    - by Meghan
    I am getting this error while I am trying to load the data into my table view. Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (73) must be equal to the number of rows contained in that section before the update (71), plus or minus the number of rows inserted or deleted from that section (3 inserted, 0 deleted). What could be wrong? Thanks EDIT : I am initializing the array on ViewWillAppear and adding new objects to the same array on Tableview's didSelectRowAtIndexPath method Here is the code On viewWillAppear : cellTextArray = [[NSMutableArray alloc] init]; [cellTextArray addObjectsFromArray:newPosts]; Here is the code which modifies the array on didSelectRowAtIndexPath : [cellTextArray addObjectsFromArray:newPosts]; NSMutableArray *insertIndexPaths = [NSMutableArray array]; for (NSUInteger item = count; item < count + newCount; item++) { [insertIndexPaths addObject:[NSIndexPath indexPathForRow:item inSection:0]]; } [self.table beginUpdates]; [self.table insertRowsAtIndexPaths:insertIndexPaths withRowAnimation:UITableViewRowAnimationFade]; [self.table endUpdates]; [self.table scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionNone animated:YES]; NSIndexPath *selected = [self.table indexPathForSelectedRow]; if (selected) { [self.table deselectRowAtIndexPath:selected animated:YES]; } Here newPosts is an array which has the values that are added to cellTextArray on didSelectRowAtIndexPath method and viewWillAppear method.

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  • Error when creating an image from a UIView

    - by Raphael Pinto
    Hi, I'm creating an image from a view whith the folowing code : UIGraphicsBeginImageContext(myView.bounds.size); [myView.layer renderInContext:UIGraphicsGetCurrentContext()]; UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil); The image is created in the user album but in the consol I get this : 2010-05-11 10:17:17.974 myApp[3875:1807] sqlite error 8 [attempt to write a readonly database] 2010-05-11 10:17:18.014 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3d87f 0x34e3b029 0x34e3b22b 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.077 myApp[3875:1807] sqlite error 8 [attempt to write a readonly database] 2010-05-11 10:17:18.087 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b053 0x34e3b22b 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.091 myApp[3875:1807] sqlite error 8 [attempt to write a readonly database] 2010-05-11 10:17:18.095 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b085 0x34e3b22b 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.111 myApp[3875:1807] sqlite error 1 [SQL logic error or missing database] 2010-05-11 10:17:18.115 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3d87f 0x34e3b029 0x34e3b4dd 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.120 myApp[3875:1807] sqlite error 1 [SQL logic error or missing database] 2010-05-11 10:17:18.124 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b053 0x34e3b4dd 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.129 myApp[3875:1807] sqlite error 1 [cannot commit - no transaction is active] 2010-05-11 10:17:18.133 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b085 0x34e3b4dd 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 I don't know where the problem come from. Can you help me?

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  • Silverlight 4 webclient authentication - anyone have this working yet?

    - by Toran Billups
    So one of the best parts about the new Silverlight 4 beta is that they finally implemented the big missing feature of the networking stack - Network Credentials! In the below I have a working request setup, but for some reason I get a "security error" when the request comes back - is this because twitter.com rejected my api call or something that I'm missing in code? It might be good to point out that when I watch this code execute via fiddler it shows that the xml file for cross domain is pulled down successfully, but that is the last request shown by fiddler ... public void RequestTimelineFromTwitterAPI() { WebRequest.RegisterPrefix("https://", System.Net.Browser.WebRequestCreator.ClientHttp); WebClient myService = new WebClient(); myService.AllowReadStreamBuffering = true; myService.UseDefaultCredentials = false; myService.Credentials = new NetworkCredential("username", "password"); myService.UseDefaultCredentials = false; myService.OpenReadCompleted += new OpenReadCompletedEventHandler(TimelineRequestCompleted); myService.OpenReadAsync(new Uri("https://twitter.com/statuses/friends_timeline.xml")); } public void TimelineRequestCompleted(object sender, System.Net.OpenReadCompletedEventArgs e) { //anytime I query for e.Result I get a security error }

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  • Spring Controller's URL request mapping not working as expected

    - by Atharva
    I have created a mapping in web.xml something like this: <servlet> <servlet-name>dispatcher</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>dispatcher</servlet-name> <url-pattern>/about/*</url-pattern> </servlet-mapping> In my controller I have something like this: import org.springframework.stereotype.Controller; @Controller public class MyController{ @RequestMapping(value="/about/us", method=RequestMethod.GET) public ModelAndView myMethod1(ModelMap model){ //some code return new ModelAndView("aboutus1.jsp",model); } @RequestMapping(value="/about", method=RequestMethod.GET) public ModelAndView myMethod2(ModelMap model){ //some code return new ModelAndView("aboutus2.jsp",model); } } And my dispatcher-servlet.xml has view resolver like: <mvc:annotation-driven/> <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:viewClass="org.springframework.web.servlet.view.JstlView" p:prefix="/WEB-INF/jsp/" p:suffix=".jsp"/> To my surprise: request .../about/us is not reaching to myMethod1 in the controller. The browser shows 404 error. I put a logger inside the method but it isn't printing anything, meaning, its not being executed. .../about works fine! What can be the done to make .../about/us request work? Any suggestions?

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  • jqtouch - panels appear on page, class="back" not working in Safari

    - by user564816
    I'm trying to get a demo working that was used in J. Stark's webinar on Safari Books Online (still available for viewing). I think I've followed the code example correctly, but the class="back" objects used to return from the "blog", "contacts", "settings" and "about" panels do not work, though the correct address shows in the nav area at the base of the browser window when I hover the mouse over the respective link. The panels-- which should slide in and out when called by their respective class"arrow" elements-- appear on the main page, nor do they animate correctly. Browser is Safari 5.0.3(6533.19.4); jquery-1.3.2; jqtouch freshly downloaded from the jqt website. Obviously I'm missing something simple. I'd sincerely appreciate anyone's help who sees what I'm doing wrong. Thanks for considering my question. View the app and source code (use view source in your browser) here. Sat 8 January 2011: 1 48 AM UPDATE in response to JS's comments: Most humble thanks for your note. Didn't want to impose on your server, so the URL for jqtouch.min.css points to a version on my server @ fastermac.net. There's something further amiss, I believe. On load, page still shows the elements that should be invisible until called by clicking class="arrow" elements. Animations not yet wiggling. Did get them to wiggle at one point, but "flip," for instance, landed then on a black page-- not the targeted panel. Probably something obvious, but I'm missing it after some considerable due diligence. Again, thanks for your note. Any further illumination would be sincerely appreciated.

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  • Does jQuery have an equivalent to Prototype's Element.identify?

    - by Alan Storm
    Is there a built in method or defacto default plugin that will let you automatically assign an unique ID to an element in jQuery, or do you need to implement something like this yourself? I'm looking for the jQuery equivalent to Prototype's identify method Here's an example. I have some HTML structure on a page that looks like this <span id="prefix_1">foo bar</span> ... <div id="foo"> <span></span> <span></span> <span></span> </div> I want to assign each of the spans an ID that will be unique to the page. So after calling something like this $('#foo span').identify('prefix'); //fake code, no such method The rendered DOM would look something like this <span id="prefix_1">foo bar</span> ... <div id="foo"> <span id="prefix_2"></span> <span id="prefix_3"></span> <span id="prefix_4"></span> </div> Is there anything official-ish/robust for jQuery, or is this something most jQuery developers roll on their own?

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  • Why is UseCompatibleTextRendering needed here?

    - by HotOil
    Hi, I think I'm missing something fundamental. Please tell me what it is, if you can. I have developed a little C++ WinForms app using VS2008. So it is built using .NET 3.5 SP1. My development box is Win7, if that matters. The default value of UseCompatibleTextRendering property in WinForms controls is false in this version of VStudio. And this should not matter to me, I don't think. I don't have any custom-drawn text or controls. The app looks good running on my Win7 box. If I package it up (dragging along .NET 3.5) and install it on one of our WinXP desktops, the buttons and labels don't look good; the text is chopped off in them. If I set UseCompatibleTextRendering to true and then run it on the XP boxes, the text fits into the buttons and labels. My question is: Why? The installation puts .Net 3.5 on the XP boxes, so the app should be able to find and use the right version of WinForms, right? I should note that before I put my app + .NET 3.5 on these boxes, they have no .NET at all. They do not get automatic Microsoft updates; our IT guy gates the patches and upgrades. [ This sort of thing has happened before with apps I create.. they look/work great on the Engineering machines, because we maintain those and they mostly have up-to-date stuff. When they are run on the corporate boxes, they usually don't run and need the VCredist installed. ] Back to the question at hand: The text looks better with the UseCompatibleTextRendering set to false, so I'd rather keep it that way, if I can. I'd like to understand what might be missing on those XP boxes that is making the text not fit. Thanks S

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  • Minimizing server load in case of many XMLHttpRequest calls

    - by user1888975
    I am making a website where users are to like some articles. Whenever the like button is clicked I am sending a XMLHttpRequest to the server to run a file called like_clicked.php along with the get data of article id and user id. This file takes article id and user id and updates the sql database and also adds a node in an xml file related to the user. This is the first time I am doing something for mass usage. I am worried about the server load when too many users call the like_clicked.php file. Please help me, if this method is ok. I am also thinking of an alternative in case the above method fails. I am thinking of making many like_clicked files (namely like_clicked1.php, like_clicked2.php ... ) to minimize load on a single i-node. Is there a method to detect that it is better to call the next like_clicked file. Here we would need to detect how many calls per unit time are coming for the particular file. How do we handle this? Thanks in advance.

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  • Has subversion lost some of my revisions in a branch?

    - by BombDefused
    I've been working on my project using a subversion branch. I've used the branching feature few times before without issue, until today. I've come to merge back into the trunk, and noticed that not everything from my branch was there. I go back to my project folder which I've been committing to the branch and look at the log messages using TortoiseSVN (the command line basic log command shows the same). See the attached image. The revision numbers go up incrementally, until revision 303 (the last trunk revision was 299). Then there are numbers missing. The latest commit, about half an hour ago was 316, but it doesn't show up in the log for the branch. Trying to commit the files again doesn't do anything. I am the only person committing to this repository at present. The missing revisions do not show up in the log for the trunk project. What's going on here. Is this a bug or am I doing something wrong? Update - the revisions do show in the repo browser (Thanks Antonio Perez), but I don't understand why they are not being included with the merge?

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  • Basic user authentication with records in AngularFire

    - by ajkochanowicz
    Having spent literally days trying the different, various recommended ways to do this, I've landed on what I think is the most simple and promising. Also thanks to the kind gents from this SO question: Get the index ID of an item in Firebase AngularFire Curent setup Users can log in with email and social networks, so when they create a record, it saves the userId as a sort of foreign key. Good so far. But I want to create a rule so twitter2934392 cannot read facebook63203497's records. Off to the security panel Match the IDs on the backend Unfortunately, the docs are inconsistent with the method from is firebase user id unique per provider (facebook, twitter, password) which suggest appending the social network to the ID. The docs expect you to create a different rule for each of the login method's ids. Why anyone using 1 login method would want to do that is beyond me. (From: https://www.firebase.com/docs/security/rule-expressions/auth.html) So I'll try to match the concatenated auth.provider with auth.id to the record in userId for the respective registry item. According to the API, this should be as easy as In my case using $registry instead of $user of course. { "rules": { ".read": true, ".write": true, "registry": { "$registry": { ".read": "$registry == auth.id" } } } } But that won't work, because (see the first image above), AngularFire sets each record under an index value. In the image above, it's 0. Here's where things get complicated. Also, I can't test anything in the simulator, as I cannot edit {some: 'json'} To even authenticate. The input box rejects any input. My best guess is the following. { "rules": { ".write": true, "registry": { "$registry": { ".read": "data.child('userId').val() == (auth.provider + auth.id)" } } } } Which both throws authentication errors and simultaneously grants full read access to all users. I'm losing my mind. What am I supposed to do here?

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  • Transfering a set with a Wildcarded Generic to a List in Java

    - by Daniel Bingham
    I have a data type that contains a set and a method that expects List<? extends MyClass>. The data type has Set<? extends MyClass>. I need to be able to move the stuff out of the set and into the List. The order it goes into the list doesn't matter, it just needs to start keeping track of it so that it can be reordered when displayed. Suffice to say that changing the Set into a List in the data type is out of the question here. This seems pretty easy at first. Create a new method that takes a Set instead of a List, changes it into a list and then passes it on to the old method that just took a list. The problem comes in changing the set to a list. public void setData(Set<? extends MyClass> data) { List<? extends Myclass> newData = ArrayList< /* What goes here? */ >(); for(ConcordaEntityBean o : data) { newData.add(o); } setData(newData); } Obviously, I can't instantiate an ArrayList with a wildcard, it chokes. I don't know the type at that point. Is there some way to pull the type out of data and pass it to ArrayList? Can I just instantiate it with MyClass? Is there some other way to do this?

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  • em.createQuery keeps returning null

    - by Developer106
    I have this application which i use JSF 2.0 and EclipseLink, i have entities created for a database made in MySQL, Created these entities using netbeans 7.1.2, it gets created automaticly. Then i use session beans to work with these entities, the thing is the em.createQuery always returns a null, though I checked NamedQueries in the entities and they perfectly match a sample from the entities named queries:- @NamedQueries({ @NamedQuery(name = "Users.findAll", query = "SELECT u FROM Users u"), @NamedQuery(name = "Users.findByUserId", query = "SELECT u FROM Users u WHERE u.userId = :userId"), @NamedQuery(name = "Users.findByUsername", query = "SELECT u FROM Users u WHERE u.username = :username"), @NamedQuery(name = "Users.findByEmail", query = "SELECT u FROM Users u WHERE u.email = :email"), notice how i use this findByEmail query in the session bean :- public Users findByEmail(String email){ em.getTransaction().begin(); String find = "Users.findByEmail"; Query query = em.createNamedQuery(find); query.setParameter("email", email); Users user = (Users) query.getSingleResult(); but it always returns null from this em.createNamedQuery, i tried using .createQuery first but it also was no good. the stacktrace of the exception Caused by: java.lang.NullPointerException at com.readme.entities.sessionBeans.UsersFacade.findByEmail(UsersFacade.java:48) at com.readme.user.signup.SignupBean.checkAvailability(SignupBean.java:137) at com.readme.user.signup.SignupBean.save(SignupBean.java:146) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) What Seems To Be The Problem Here ?

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  • Why cant we create Object if constructor is in private section?

    - by Abhi
    Dear all I want to know why cant we create object if the constructor is in private section. I know that if i make a method static i can call that method using <classname> :: <methodname(...)>; But why cant we create object is my doubt... I also know if my method is not static then also i can call function by the following... class A { A(); public: void fun1(); void fun2(); void fun3(); }; int main() { A *obj =(A*)malloc(sizeof(A)); //Here we can't use new A() because constructor is in private //but we can use malloc with it, but it will not call the constructor //and hence it is harmful because object may not be in usable state. obj->fun1(); obj->fun2(); obj->fun3(); } So only doubt is why cant we create object when constructor is in private section? Thanks in advance

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  • How to run a long task in backgroung in iOS applications?

    - by John Canady
    I am developing an application which requires running a task in background. I am trying this by calling a method which will retrieve(download) data from web server through web services. this method will call some more methods which are in different view controller classes. Here when I tap on home button of device, the method is calling but no further execution of the remaining code. This is the code I have written in (void)applicationDidEnterBackground:(UIApplication )application { UIApplication app = [UIApplication sharedApplication]; UIBackgroundTaskIdentifier bgTask = 0; bgTask = [app beginBackgroundTaskWithExpirationHandler:^{ [app endBackgroundTask:bgTask]; bgTask = UIBackgroundTaskInvalid; }]; // Start the long-running task and return immediately. dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ // Do the work associated with the task. NSString *updatekey = [[NSUserDefaults standardUserDefaults] objectForKey:@"updatesetting"]; if([updatekey isEqualToString:@"enabled"]) { DataSettingsView *periodicUpdate = [[DataSettingsView alloc] init]; [periodicUpdate updateDataPeriodically]; //[periodicUpdate viewDidLoad]; //[periodicUpdate release]; } [app endBackgroundTask:bgTask]; bgTask = UIBackgroundTaskInvalid; }); } some one please help me in this background execution of long tasks with some example of code. Some help will appreciated and helpful to me.

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  • Efficient database access when dealing with multiple abstracted repositories

    - by Nathan Ridley
    I want to know how most people are dealing with the repository pattern when it involves hitting the same database multiple times (sometimes transactionally) and trying to do so efficiently while maintaining database agnosticism and using multiple repositories together. Let's say we have repositories for three different entities; Widget, Thing and Whatsit. Each repository is abstracted via a base interface as per normal decoupling design processes. The base interfaces would then be IWidgetRepository, IThingRepository and IWhatsitRepository. Now we have our business layer or equivalent (whatever you want to call it). In this layer we have classes that access the various repositories. Often the methods in these classes need to do batch/combined operations where multiple repositories are involved. Sometimes one method may make use of another method internally, while that method can still be called independently. What about, in this scenario, when the operation needs to be transactional? Example: class Bob { private IWidgetRepository _widgetRepo; private IThingRepository _thingRepo; private IWhatsitRepository _whatsitRepo; public Bob(IWidgetRepository widgetRepo, IThingRepository thingRepo, IWhatsitRepository whatsitRepo) { _widgetRepo = widgetRepo; _thingRepo= thingRepo; _whatsitRepo= whatsitRepo; } public void DoStuff() { _widgetRepo.StoreSomeStuff(); _thingRepo.ReadSomeStuff(); _whatsitRepo.SaveSomething(); } public void DoOtherThing() { _widgetRepo.UpdateSomething(); DoStuff(); } } How do I keep my access to that database efficient and not have a constant stream of open-close-open-close on connections and inadvertent invocation of MSDTS and whatnot? If my database is something like SQLite, standard mechanisms like creating nested transactions are going to inherently fail, yet the business layer should not have to be concerning itself with such things. How do you handle such issues? Does ADO.Net provide simple mechanisms to handle this or do most people end up wrapping their own custom bits of code around ADO.Net to solve these types of problems?

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  • Cannot use a Like query in a JSP prepared statement?

    - by SeerUK
    OK, first the query code and query: ps = conn.prepareStatement("select instance_id, ? from eam_measurement where resource_id in (select RESOURCE_ID from eam_res_grp_res_map where resource_group_id = ?) and DSN like '?' order by 2"); ps.setString(1,"SUBSTR(DSN,27,16)"); ps.setInt(2,defaultWasGroup); ps.setString(3,"%Module=jvmRuntimeModule:freeMemory%"); rs = ps.executeQuery(); while (rs.next()) { bla blah blah blah ... Returns an empty resultSet. Through basic debugging I have found its the 3rd bind that is the problem i.e. DSN like '?' I have tried all kinds of variations, the most sensible of which seemed to be using: DSN like concat('%',?,'%') bit that doesn' work as I am missing the ' ' either side of the concatenated string so I try DSN like ' concat('%',Module=P_STAG_JDBC01:poolSize,'%') ' order by 2 but I just can't seem to find a way to get them in that works. What am I missing? :) Thanks!

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  • Best way to carry & modify a variable through various instances and functions?

    - by bobsoap
    I'm looking for the "best practice" way to achieve a message / notification system. I'm using an OOP-based approach for the script and would like to do something along the lines of this: if(!$something) $messages->add('Something doesn\'t exist!'); The add() method in the messages class looks somewhat like this: class messages { public function add($new) { $messages = $THIS_IS_WHAT_IM_LOOKING_FOR; //array $messages[] = $new; $THIS_IS_WHAT_IM_LOOKING_FOR = $messages; } } In the end, there is a method in which reads out $messages and returns every message as nicely formatted HTML. So the questions is - what type of variable should I be using for $THIS_IS_WHAT_IM_LOOKING_FOR? I don't want to make this use the database. Querying the db every time just for some messages that occur at runtime and disappear after 5 seconds just seems like overkill. Using global constants for this is apparently worst practice, since constants are not meant to be variables that change over time. I don't even know if it would work. I don't want to always pass in and return the existing $messages array through the method every time I want to add a new message. I even tried using a session var for this, but that is obviously not suited for this purpose at all (it will always be 1 pageload too late). Any suggestions? Thanks!

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  • MS Exam 70-536 - How to throw and handle exception from thread?

    - by Max Gontar
    Hello! In MS Exam 70-536 .Net Foundation, Chapter 7 "Threading" in Lesson 1 Creating Threads there is a text: Be aware that because the WorkWithParameter method takes an object, Thread.Start could be called with any object instead of the string it expects. Being careful in choosing your starting method for a thread to deal with unknown types is crucial to good threading code. Instead of blindly casting the method parameter into our string, it is a better practice to test the type of the object, as shown in the following example: ' VB Dim info As String = o as String If info Is Nothing Then Throw InvalidProgramException("Parameter for thread must be a string") End If // C# string info = o as string; if (info == null) { throw InvalidProgramException("Parameter for thread must be a string"); } So, I've tried this but exception is not handled properly (no console exception entry, program is terminated), what is wrong with my code (below)? class Program { static void Main(string[] args) { Thread thread = new Thread(SomeWork); try { thread.Start(null); thread.Join(); } catch (InvalidProgramException ex) { Console.WriteLine(ex.Message); } finally { Console.ReadKey(); } } private static void SomeWork(Object o) { String value = (String)o; if (value == null) { throw new InvalidProgramException("Parameter for "+ "thread must be a string"); } } } Thanks for your time!

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  • Releasing Autopool crashes on iOS 4.0 (and only on 4.0)

    - by samsam
    Hi there. I'm wondering what could cause this. I have several methods in my code that i call using performSelectorInBackground. Within each of these methods i have an Autoreleasepool that is being alloced/initialized at the beginning and released at the end of the method. this perfectly works on iOS 3.1.3 / 3.2 / 4.2 / 4.2.1 but it fataly crashes on iOS 4.0 with a EXC_BAD_ACCESS Exception that happens after calling [myPool release]. After I noticed this strange behaviour I was thinking about rewriting portions of my code and to make my app "less parallel" in case that the client os is 4.0. After I did that, the next point where the app crashed was within the ReachabilityCallback-Method from Apples Reachability "Framework". well, now I'm not quite sure what to do. The things i do within my threaded methods is pretty simple xml parsing (no cocoa calls or stuff that would affect the UI). After each method finishes it posts a notification which the coordinating-thread listens to and once all the parallelized methods have finished, the coordinating thread calls viewcontrollers etc... I have absolutely no clue what could cause this weird behaviour. Especially because Apples Code fails as well. any help is greatly appreciated! thanks, sam

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