Search Results

Search found 5968 results on 239 pages for 'generator expression'.

Page 227/239 | < Previous Page | 223 224 225 226 227 228 229 230 231 232 233 234  | Next Page >

• Is this implementation truely tail-recursive?

  - by CFP

  Hello everyone! I've come up with the following code to compute in a tail-recursive way the result of an expression such as 3 4 * 1 + cos 8 * (aka 8*cos(1+(3*4))) The code is in OCaml. I'm using a list refto emulate a stack. type token = Num of float | Fun of (float->float) | Op of (float->float->float);; let pop l = let top = (List.hd !l) in l := List.tl (!l); top;; let push x l = l := (x::!l);; let empty l = (l = []);; let pile = ref [];; let eval data = let stack = ref data in let rec _eval cont = match (pop stack) with | Num(n) -> cont n; | Fun(f) -> _eval (fun x -> cont (f x)); | Op(op) -> _eval (fun x -> cont (op x (_eval (fun y->y)))); in _eval (fun x->x) ;; eval [Fun(fun x -> x**2.); Op(fun x y -> x+.y); Num(1.); Num(3.)];; I've used continuations to ensure tail-recursion, but since my stack implements some sort of a tree, and therefore provides quite a bad interface to what should be handled as a disjoint union type, the call to my function to evaluate the left branch with an identity continuation somehow irks a little. Yet it's working perfectly, but I have the feeling than in calling the _eval (fun y->y) bit, there must be something wrong happening, since it doesn't seem that this call can replace the previous one in the stack structure... Am I misunderstanding something here? I mean, I understand that with only the first call to _eval there wouldn't be any problem optimizing the calls, but here it seems to me that evaluation the _eval (fun y->y) will require to be stacked up, and therefore will fill the stack, possibly leading to an overflow... Thanks!

  Read the article

• WPF - Two way binding use a user control...binding to object, not an element!

  - by Scott

  I created an object with a simple property with a default value. I then created a user control that has a text box in it. I set the datacontext of the user control to the object. The text box correctly shows the properties default value but I can't seem to update the property value when the user changes the text box value. I created a simple project to illustrate my code. Thanks for the help!! public partial class UserControl1 : UserControl { public UserControl1() { InitializeComponent(); } private string _titleValue; public string TitleValue { get { return _titleValue; } set { _titleValue = value; textBox1.Text = _titleValue; } } public static readonly DependencyProperty TitleValueProperty = DependencyProperty.Register( "TitleValue", typeof(string), typeof(UserControl1), new FrameworkPropertyMetadata(new PropertyChangedCallback(titleUpdated)) ); //Don't think I should need to do this!!! private static void titleUpdated(DependencyObject d, DependencyPropertyChangedEventArgs e) { ((UserControl1)d).TitleValue = (string)e.NewValue; } } <UserControl x:Class="WpfApplication1.UserControl1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="300"> <Grid> <TextBox Height="23" HorizontalAlignment="Left" Margin="94,97,0,0" Name="textBox1" VerticalAlignment="Top" Width="120" Text="{Binding Path=TitleValue, Mode=TwoWay}"/> </Grid> </UserControl> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); var dummy = new DummyObject("This is my title."); userControl11.DataContext = dummy; } private void button1_Click(object sender, RoutedEventArgs e) { MessageBox.Show("The value is: " + ((DummyObject)userControl11.DataContext).Title); } } <Window x:Class="WpfApplication1.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525" xmlns:my="clr-namespace:WpfApplication1"> <Grid> <my:UserControl1 HorizontalAlignment="Left" Margin="95,44,0,0" x:Name="userControl11" VerticalAlignment="Top" Height="191" Width="293" TitleValue="{Binding Path=Title, Mode=TwoWay}"/> <Button Content="Check Value" Height="23" HorizontalAlignment="Left" Margin="20,12,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" /> </Grid> </Window>

  Read the article

• Paging & Sorting grids with ASP.Net MVC

  - by Scott Ivey

  I'm new to MVC, and am not following how you'd do paging and sorting on a grid. I'm used to using the asp.Net GridView control with an ObjectDataSource pointed at objects in our business layer - and in that case the ODS handles all of the paging & sorting using the methods that our ORM generates on the objects. I've looked at using the same ORM with MVC - and things work out fine there - i just loop thru the collections to build the table on the page - but without the ODS to handle the paging & sorting, i'm confused as to how I'd handle that. Would I have a separate controller for the paging and sorting? I'm not sure what the best practices are for this scenario, so if someone can point me in the right direction it would be much appreciated. Edit: Ok, so I understand that I need to roll my own - but where do I start? I've created a CustomerController, and a view that displays a table of customers that looks like below - and I want to sort on FirstName or LastName columns. My Model has a Sort() method on it that'll take a string sort expression in the format that would be used by a GridView/ODS pair. Would I create a new Action on my CustomerController called Sort, and put an ActionLink in my header? <table> <tr> <th> First Name </th> <th> Last Name </th> </tr> <% foreach (var item in Model) { %> <tr> <td> <%= Html.Encode(item.FirstName) %> </td> <td> <%= Html.Encode(item.LastName) %> </td> </tr> <% } %> </table>

  Read the article

• PHP: How to automate building a 100 <UL>/<LI> menuitems, while keeping the Menu Structure File Flat / Simply Managable?

  - by Sam

  Above: current "stupid" menu. (entire ul/li menu for javascript menu system) + (some li lines as page-specific submenu) Hi folks! With passion for automation and elegancy, but limited knowledge/knowhow, im stuck with "my hands in my hair" as we Dutch say, for my current menu system works perfectly, but is a pain in the a*s to update! So, i would appreciate it greatly, if you can suggest how to automate this in php: how to let the php generate the html menu code basing on a flat menu input file with TABS indented. OLD SITUATION <ul> <!-- about 100 of these <li>....</li> lines --> <li><a href="carrot.php"><p class="mnu" style="background-position:0 -820px"><? echo __("carrot juice") ?></p></a></li> <!-- lots of data, with only little bit thats really the menu itself--> </ul a javascript file reads a ul/li structure as input to build menu of format in that ul/li, the items with a hyperlink and sprite-bg position represent webpages, (inside LI) while items without hyperlink and sprite-bg are just headers of that menusection, (inside H6) to highlight the current page in the menu, the javascript menumaker uses an id number. this number corresponds to the consequtive li that is a webpage, skips h6 headers correctly. these h6 headers are only there for when importing sections of the same menu as submenu. non-li headers are not shown in menu, nore counted by the javascript menu for their ID. to know which page should be shown, i have to count from ID 0, the li items till finding the current webpage in the li structure and then manually put it in each webpage! BUT: changing an item in li order, means stupidly re-counting their entire li again! each webpage has an icon (= sprite bg-position numer), which is also used in the webpage. INTENDED RESULT I dream of, once setting what the current webpage is (e.g carrot.php) the menu system automatically "finds" and "counts" the li's and returns the id nr (for proper highlight of main menu); generates the entire menu html, and depending on which headings are set for submenu, (e.g. meals, drinks) generates those submenu (entire section below each given header); ginally adds h5 highlight inside the li of that submenu item. For the menu, i wish an easily readable, simple plain txt menu that is indented with tabs, (each tab is one depth for example) and further tabs follow for url and sprite position of icon. MY DREAM MENU-MANAGEMENT FILE |>TAB SEPARATED/INDENTED FLATMENU FILE |MUST BE CALCULATED BY PHP: |>MENUTEXT============URL=============SPRITE=====|ID===TAG================== |>about "#" -520 |00 li |> INFORMATION |—— h6 |> physical state "physical.php" -920 |01 li |> mental health "mental.php" -10 |02 li |> |>apetite "#" -1290 |03 li |> meals "#" -600 |04 li |> COLD MEAL |—— h6 |> egg salade "salad.php" -1040 |05 li |> salmon fish "salmon.php" -540 |06 li |> HOT MEAL |—— h6 |> spare ribs "spareribs.php" -120 |07 li |> di macaroni "macaroni.php" -870 |08 li |> |> drinks "#" -230 |09 li |> JUCY DRINK |—— h6 |> carrot juice "carrot.php" -820 |10 li |> mango hive "mango.php" -270 |11 li DESIRED CHRONOLOGY php outputs the entire ul/li html so the javascript can show the menu: webpage items go inside li tags, and header items go inside h6 tags, e.g. <h6>JUCY DRINK</h6> Each website page has a url filename [eg: salad.php]. Based on this given fact, the php menu generator detects the pagename, gives the IDnr of the position of that page according to the li-item nr and sets variable for javascript to highlight current menu item. the menu items below the specified headers are loaded as submenu in which the current page.php is wrapped inside h5 to highlight current page in submenu: e.g. (<li><h5><a href="carrot.php"><p>..etc..</p></h5></li> Question Which methods / steps / (chronological)ways are there for doing this? I am no good in php programming, but am learning it so please dont write any code without a line of comment why I should use that method etc. Where do I start? If I am unclear in my question, please ask. Thanks. Much appreciated!! Concrete Task List from the provided Comments/Answers, sofar: (RobertB) First, get some PHP code working that can read through a tab-delimited file and put the data into an appropriate data structure. NOW WORKING AT THIS

  Read the article

• Why does this textbox binding example work in WPF but not in Silverlight?

  - by Edward Tanguay

  Why is it in the following silverlight application that when I: change the default text in the first textbox move the cursor to the second text box (i.e. take focus off first textbox) click the button that inside the button handler, it still has the old value "default text"? What do I have to do to get the binding to work in Silverlight? The same code works fine in WPF. XAML: <UserControl x:Class="TestUpdate123.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480"> <StackPanel Margin="10" HorizontalAlignment="Left"> <TextBox Text="{Binding InputText}" Height="200" Width="600" Margin="0 0 0 10"/> <StackPanel HorizontalAlignment="Left"> <Button Content="Convert" Click="Button_Convert_Click" Margin="0 0 0 10"/> </StackPanel> <TextBox Height="200" Width="600" Margin="0 0 0 10"/> <TextBlock Text="{Binding OutputText}"/> </StackPanel> </UserControl> Code Behind: using System.Windows; using System.Windows.Controls; using System.ComponentModel; namespace TestUpdate123 { public partial class MainPage : UserControl, INotifyPropertyChanged { #region ViewModelProperty: InputText private string _inputText; public string InputText { get { return _inputText; } set { _inputText = value; OnPropertyChanged("InputText"); } } #endregion #region ViewModelProperty: OutputText private string _outputText; public string OutputText { get { return _outputText; } set { _outputText = value; OnPropertyChanged("OutputText"); } } #endregion public MainPage() { InitializeComponent(); DataContext = this; InputText = "default text"; } private void Button_Convert_Click(object sender, RoutedEventArgs e) { OutputText = InputText; } #region INotifiedProperty Block public event PropertyChangedEventHandler PropertyChanged; protected void OnPropertyChanged(string propertyName) { PropertyChangedEventHandler handler = PropertyChanged; if (handler != null) { handler(this, new PropertyChangedEventArgs(propertyName)); } } #endregion } }

  Read the article

• Search row with highest number of cells in a row with colspan

  - by user593029

  What is the efficient way to search highest number of cells in big table with numerous colspan (merge cells ** colspan should be ignored so in below example highest number of cells is 4 in first row). Is it js/jquery with reg expression or just the loop with bubble sorting. I got one link as below explainig use of regex is it ideal way ... can someone suggest pseudo code for this. High cpu consumption due to a jquery regex patch <table width="156" height="84" border="0" > <tbody> <tr style="height:10px"> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> </tr> <tr style="height:10px"> <td width="10" style="width:10px; height:10px" colspan="2"/> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> </tr> <tr style="height:10px"> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px" colspan="2"/> </tr> <tr style="height:10px"> <td width="10" style="width:10px; height:10px" colspan="2"/> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> </tr> </tbody> </table>

  Read the article

• Poor performance / speed of regex with lookahead

  - by Hugo Zaragoza

  I have been observing extremely slow execution times with expressions with several lookaheads. I suppose that this is due to underlying data structures, but it seems pretty extreme and I wonder if I do something wrong or if there are known work-arounds. The problem is determining if a set of words are present in a string, in any order. For example we want to find out if two terms "term1" AND "term2" are somewhere in a string. I do this with the expresion: (?=.*\bterm1\b)(?=.*\bterm2\b) But what I observe is that this is an order of magnitude slower than checking first just \bterm1\b and just then \bterm2\b This seems to indicate that I should use an array of patterns instead of a single pattern with lookaheads... is this right? it seems wrong... Here is an example test code and resulting times: public static void speedLookAhead() { Matcher m, m1, m2; boolean find; int its = 1000000; // create long non-matching string char[] str = new char[2000]; for (int i = 0; i < str.length; i++) { str[i] = 'x'; } String test = str.toString(); // First method: use one expression with lookaheads m = Pattern.compile("(?=.*\\bterm1\\b)(?=.*\\bterm2\\b)").matcher(test); long time = System.currentTimeMillis(); ; for (int i = 0; i < its; i++) { m.reset(test); find = m.find(); } time = System.currentTimeMillis() - time; System.out.println(time); // Second method: use two expressions and AND the results m1 = Pattern.compile("\\bterm1\\b").matcher(test); m2 = Pattern.compile("\\bterm2\\b").matcher(test); time = System.currentTimeMillis(); ; for (int i = 0; i < its; i++) { m1.reset(test); m2.reset(test); find = m1.find() && m2.find(); } time = System.currentTimeMillis() - time; System.out.println(time); } This outputs in my computer: 1754 150

  Read the article

• Working with friends. Poor career choice?

  - by a_person

  Hi all, Hope you can help me solve somewhat of a moral dilemma. Some time ago, after just a few years of living in U.S. and having to take any job I could get my hands on a friend of mine submitted recommended me for an open position at the company that he was working for. I could have not been happier. I do not have a degree of any sort, however, by being passionate about CS and with constant drive for self education I've became a somewhat of a strong generalist. Every place I worked for recognized me for that quality and used me on various projects where set of technology in hand had no overlap with set of knowledge of the team members. Rapidly I've advanced to Sr. Programmer position and the trend of me following a friend from one place to another have started and continued on for a few years. My friend's goal always been to become an IT Director, mine is to become the best programmer I can be. To my knowledge I've accommodated his goals as much as I could by taking a back seat, and letting him take the lead. Fast forward to today. He's a manager, and I am on his team. I am unhappy and I in considerable amount of suffering. I am not being utilized to my potential, it's almost exact opposite, I am being micromanaged to an unhealthy extent, my decisions, and suggestions are constantly met with negative connotation. Last week I had to hear about how my friend is a better programmer than I am. My ego was ecstatic about this one /s. In addition to that working in the field of BI have exhausted itself for most parts. The only pleasure of my work is being derived from making everything as dynamic and parameter driven as possible. This is the only area where a friend of mine does not feel competent enough to actually micromanage. Because of my situation I feel a fair amount of guilt and ever growing resentment. I need your advice, maybe you've dealt with this expression of ego before, needs of self vs the needs of your friend. Is working with a friend a poor choice? Thank you for reading in.

  Read the article

• having trouble with jpa, looks to be reading from cache when told to ignore

  - by jeff

  i'm using jpa and eclipselink. it says version 2.0.2.v20100323-r6872 for eclipselink. it's an SE application, small. local persistence unit. i am using a postgres database. i have some code the wakes up once per second and does a jpa query on a table. it's polling to see whether some fields on a given record change. but when i update a field in sql, it keeps showing the same value each time i query it. and this is after waiting, creating a new entitymanager, and giving a query hint. when i query the table from sql or python, i can see the changed field. but from within my jpa query, once i've read the value, it never changes in later executions of the query -- even though the entity manager has been recreated. i've tried telling it to not look in the cache. but it seems to ignore that. very puzzling, can you help please? here is the method. i call this once every 3 seconds. the tgt.getTrlDlrs() println shows me i get the same value for this field on every call of the method ("value won't change"). even if i change the field in the database. when i query the record from outside java, i see the change right away. also, if i stop the java program and restart it, i see the new value printed out immediately: public void exitChk(EntityManagerFactory emf, Main_1 mn){ // this will be a list of the trade close targets that are active List<Pairs01Tradeclosetgt> mn_res = new ArrayList<Pairs01Tradeclosetgt>(); //this is a list of the place number in the array list above //of positions to close ArrayList<Integer> idxsToCl = new ArrayList<Integer>(); EntityManager em = emf.createEntityManager(); em.getTransaction().begin(); em.clear(); String qryTxt = "SELECT p FROM Pairs01Tradeclosetgt p WHERE p.isClosed = :isClosed AND p.isFilled = :isFilled"; Query qMn = em.createQuery(qryTxt); qMn.setHint(QueryHints.CACHE_USAGE, CacheUsage.DoNotCheckCache); qMn.setParameter("isClosed", false); qMn.setParameter("isFilled", true); mn_res = (List<Pairs01Tradeclosetgt>) qMn.getResultList(); // are there any trade close targets we need to check for closing? if (mn_res!=null){ //if yes, see whether they've hit their target for (int i=0;i<mn_res.size();i++){ Pairs01Tradeclosetgt tgt = new Pairs01Tradeclosetgt(); tgt = mn_res.get(i); System.out.println("value won't change:" + tgt.getTrlDlrs()); here is my entity class (partial): @Entity @Table(name = "pairs01_tradeclosetgt", catalog = "blah", schema = "public") @NamedQueries({ @NamedQuery(name = "Pairs01Tradeclosetgt.findAll", query = "SELECT p FROM Pairs01Tradeclosetgt p"), @NamedQuery(name = "Pairs01Tradeclosetgt.findByClseRatio", query = "SELECT p FROM Pairs01Tradeclosetgt p WHERE p.clseRatio = :clseRatio")}) public class Pairs01Tradeclosetgt implements Serializable { private static final long serialVersionUID = 1L; @Id @Basic(optional = false) @Column(name = "id") @SequenceGenerator(name="pairs01_tradeclosetgt_id_seq", allocationSize=1) @GeneratedValue(strategy=GenerationType.SEQUENCE, generator = "pairs01_tradeclosetgt_id_seq") private Integer id; and my persitence unit: <?xml version="1.0" encoding="UTF-8"?> <persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"> <persistence-unit name="testpu" transaction-type="RESOURCE_LOCAL"> <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> <class>mourv02.Pairs01Quotes</class> <class>mourv02.Pairs01Pair</class> <class>mourv02.Pairs01Trderrs</class> <class>mourv02.Pairs01Tradereq</class> <class>mourv02.Pairs01Tradeclosetgt</class> <class>mourv02.Pairs01Orderstatus</class> <properties> <property name="javax.persistence.jdbc.url" value="jdbc:postgresql://192.168.1.80:5432/blah"/> <property name="javax.persistence.jdbc.password" value="secret"/> <property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver"/> <property name="javax.persistence.jdbc.user" value="noone"/> </properties> </persistence-unit> </persistence>

  Read the article

• vb.net how to start a folder monitor service at runtime and pass on the folder path to monitor?

  - by mazrabul

  hi, I have the following windows service file: Imports System.ServiceProcess Imports System.IO Public Class fswService Dim fsw As FileSystemWatcher Dim lf As StreamWriter Protected Overrides Sub OnStart(ByVal args As String()) ' Add code here to start your service. This method should set things ' in motion so your service can do its work. lf = New StreamWriter(Application.StartupPath & "\fsw_lg.log") fsw = New FileSystemWatcher() fsw.Path = args(0) fsw.IncludeSubdirectories = True fsw.Filter = ".txt" fsw.EnableRaisingEvents = True AddHandler fsw.Created, New FileSystemEventHandler(AddressOf file_created) AddHandler fsw.Changed, New FileSystemEventHandler(AddressOf file_changed) AddHandler fsw.Deleted, New FileSystemEventHandler(AddressOf file_deleted) End Sub Public Sub file_created(ByVal obj As Object, ByVal e As FileSystemEventArgs) lf.WriteLine(Now.ToShortDateString & "-" & Now.ToShortTimeString & "-" & e.FullPath & "-created") End Sub Public Sub file_changed(ByVal obj As Object, ByVal e As FileSystemEventArgs) lf.WriteLine(Now.ToShortDateString & "-" & Now.ToShortTimeString & "-" & e.FullPath & "-changed") End Sub Public Sub file_deleted(ByVal obj As Object, ByVal e As FileSystemEventArgs) lf.WriteLine(Now.ToShortDateString & "-" & Now.ToShortTimeString & "-" & e.FullPath & "-deleted") End Sub Protected Overrides Sub OnStop() lf.Close() End Sub End Class i have the ServiceName set to fswService (same as class name). When I added an installer I also set the ServiceName for the ServiceInstaller1 as fswService. I want to start this service at runtime based on the user setting the path of the folder to be watched. To achieve this I have the following: Dim fsw_controller As New ServiceProcess.ServiceController fsw_controller.Start(fswService) 2 problems: first, intellisense error saying: 'fswService' is a type and cannot be used as an expression. second, I can not figure out a way to pass on to the service the path of the folder to watch (which is stored at My.Settings.userPath). I really thought this is how you start a service. Am I missing something? Your help is, as always, appreciated. Thanks

  Read the article

• How can I improve the recursion capabilities of my ECMAScript implementation?

  - by ChaosPandion

  After some resent tests I have found my implementation cannot handle very much recursion. Although after I ran a few tests in Firefox I found that this may be more common than I originally thought. I believe the basic problem is that my implementation requires 3 calls to make a function call. The first call is made to a method named Call that makes sure the call is being made to a callable object and gets the value of any arguments that are references. The second call is made to a method named Call which is defined in the ICallable interface. This method creates the new execution context and builds the lambda expression if it has not been created. The final call is made to the lambda that the function object encapsulates. Clearly making a function call is quite heavy but I am sure that with a little bit of tweaking I can make recursion a viable tool when using this implementation. public static object Call(ExecutionContext context, object value, object[] args) { var func = Reference.GetValue(value) as ICallable; if (func == null) { throw new TypeException(); } if (args != null && args.Length > 0) { for (int i = 0; i < args.Length; i++) { args[i] = Reference.GetValue(args[i]); } } var reference = value as Reference; if (reference != null) { if (reference.IsProperty) { return func.Call(reference.Value, args); } else { return func.Call(((EnviromentRecord)reference.Value).ImplicitThisValue(), args); } } return func.Call(Undefined.Value, args); } public object Call(object thisObject, object[] arguments) { var lexicalEnviroment = Scope.NewDeclarativeEnviroment(); var variableEnviroment = Scope.NewDeclarativeEnviroment(); var thisBinding = thisObject ?? Engine.GlobalEnviroment.GlobalObject; var newContext = new ExecutionContext(Engine, lexicalEnviroment, variableEnviroment, thisBinding); Engine.EnterContext(newContext); var result = Function.Value(newContext, arguments); Engine.LeaveContext(); return result; }

  Read the article

• c++, object life-time of anonymous (unnamed) variables

  - by Joe Steeve

  In the following code, the object constructed in the last line of 'main()', seems to be destroyed before the end of the expression. The destructor is called before the '<<' is executed. Is this how it is supposed to be? #include <string> #include <sstream> #include <iostream> using std::string; using std::ostringstream; using std::cout; class A : public ostringstream { public: A () {} virtual ~A () { string s; s = str(); cout << "from A: " << s << std::endl; } }; int main () { string s = "Hello"; A os; os << s; cout << os.str() << std::endl; A() << "checking this"; } This is the output: Hello from A: 0x80495f7 from A: Hello This is the gdb log: (gdb) b os.cxx : 18 Breakpoint 1 at 0x80492b1: file os.cxx, line 18. (2 locations) (gdb) r Starting program: /home/joe/sandbox/test/os Hello Breakpoint 1, ~A (this=0xbffff37c, __in_chrg=<value optimized out>, __vtt_parm=<value optimized out>) at os.cxx:18 18 cout << "from A: " << s << std::endl; (gdb) p s.c_str () $1 = 0x804b45c "0x80495f7" (gdb) p *s.c_str () $2 = 48 '0' (gdb) c Continuing. from A: 0x80495f7 Breakpoint 1, ~A (this=0xbffff2bc, __in_chrg=<value optimized out>, __vtt_parm=<value optimized out>) at os.cxx:18 18 cout << "from A: " << s << std::endl; (gdb) p s.c_str () $3 = 0x804b244 "Hello" (gdb) p *s.c_str () $4 = 72 'H' (gdb) c Continuing. from A: Hello Program exited normally. (gdb)

  Read the article

• C++ segmentation error when first parameter is null in comparison operator overload

  - by user1774515

  I am writing a class called Word, that handles a c string and overloads the <, , <=, = operators. word.h: friend bool operator<(const Word &a, const Word &b); word.cc: bool operator<(const Word &a, const Word &b) { if(a == NULL && b == NULL) return false; if(a == NULL) return true; if(b == NULL) return false; return a.wd < b.wd; //wd is a valid c string } main: char* temp = NULL; //EDIT: i was mistaken, temp is a char pointer Word a("blah"); //a.wd = [b,l,a,h] cout << (temp<a); i get a segmentation error before the first line of the operator< method after the last line in the main. I can correct the problem by writing cout << (a>temp); where the operator> is similarly defined and i get no errors. but my assignment requires (temp < a) to work so this is where i ask for help. EDIT: i made a mistake the first time and i said temp was of type Word, but it is actually of type char*. so i assume that the compiler converts temp to a Word using one of my constructors. i dont know which one it would use and why this would work since the first parameter is not Word. here is the constructor i think is being used to make the Word using temp: Word::Word(char* c, char* delimeters=NULL) { char *temporary = "\0"; if(c == NULL) c = temporary; check(stoppers!=NULL, "(Word(char*,char*))NULL pointer"); //exits the program if the expression is false if(strlen(c) == 0) size = DEFAULT_SIZE; //10 else size = strlen(c) + 1 + DEFAULT_SIZE; wd = new char[size]; check(wd!=NULL, "Word(char*,char*))heap overflow"); delimiters = new char[strlen(stoppers) + 1]; //EDIT: changed to [] check(delimiters!=NULL,"Word(char*,char*))heap overflow"); strcpy(wd,c); strcpy(delimiters,stoppers); count = strlen(wd); } wd is of type char* thanks for looking at this big question and trying to help. let me know if you need more code to look at

  Read the article

• Using Selenium-IDE with a rich Javascript application?

  - by Darien

  Problem At my workplace, we're trying to find the best way to create automated-tests for an almost wholly javascript-driven intranet application. Right now we're stuck trying to find a good tradeoff between: Application code in reusable and nest-able GUI components. Tests which are easily created by the testing team Tests which can be recorded once and then automated Tests which do not break after small cosmetic changes to the site XPath expressions (or other possible expressions, like jQuery selectors) naively generated from Selenium-IDE are often non-repeatable and very fragile. Conversely, having the JS code generate special unique ID values for every important DOM-element on the page... well, that is its own headache, complicated by re-usable GUI components and IDs needing to be consistent when the test is re-run. What successes have other people had with this kind of thing? How do you do automated application-level testing of a rich JS interface? Limitations We are using JavascriptMVC 2.0, hopefully 3.0 soon so that we can upgrade to jQuery 1.4.x. The test-making folks are mostly trained to use Selenium IDE to directly record things. The test leads would prefer a page-unique HTML ID on each clickable element on the page... Training the testers to write or alter special expressions (such as telling them which HTML class-names are important branching points) is a no-go. We try to make re-usable javascript components, but this means very few GUI components can treat themselves (or what they contain) as unique. Some of our components already use HTML ID values in their operation. I'd like to avoid doing this anyway, but it complicates the idea of ID-based testing. It may be possible to add custom facilities (like a locator-builder or new locator method) to the Selenium-IDE installation testers use. Almost everything that goes on occurs within a single "page load" from a conventional browser perspective, even when items are saved Current thoughts I'm considering a system where a custom locator-builder (javascript code) for Selenium-IDE will talk with our application code as the tester is recording. In this way, our application becomes partially responsible for generating a mostly-flexible expression (XPath or jQuery) for any given DOM element. While this can avoid requiring more training for testers, I worry it may be over-thinking things.

  Read the article

• Simplifying const Overloading?

  - by templatetypedef

  Hello all- I've been teaching a C++ programming class for many years now and one of the trickiest things to explain to students is const overloading. I commonly use the example of a vector-like class and its operator[] function: template <typename T> class Vector { public: T& operator[] (size_t index); const T& operator[] (size_t index) const; }; I have little to no trouble explaining why it is that two versions of the operator[] function are needed, but in trying to explain how to unify the two implementations together I often find myself wasting a lot of time with language arcana. The problem is that the only good, reliable way that I know how to implement one of these functions in terms of the other is with the const_cast/static_cast trick: template <typename T> const T& Vector<T>::operator[] (size_t index) const { /* ... your implementation here ... */ } template <typename T> T& Vector<T>::operator[] (size_t index) { return const_cast<T&>(static_cast<const Vector&>(*this)[index]); } The problem with this setup is that it's extremely tricky to explain and not at all intuitively obvious. When you explain it as "cast to const, then call the const version, then strip off constness" it's a little easier to understand, but the actual syntax is frightening,. Explaining what const_cast is, why it's appropriate here, and why it's almost universally inappropriate elsewhere usually takes me five to ten minutes of lecture time, and making sense of this whole expression often requires more effort than the difference between const T* and T* const. I feel that students need to know about const-overloading and how to do it without needlessly duplicating the code in the two functions, but this trick seems a bit excessive in an introductory C++ programming course. My question is this - is there a simpler way to implement const-overloaded functions in terms of one another? Or is there a simpler way of explaining this existing trick to students? Thanks so much!

  Read the article

• Remove Item From Object SubList (LINQ)

  - by X3074861X

  I have an object that looks like this : public class Consortium { public string Id { get; set; } [JsonConverter(typeof(EnumDescriptionConverter))] public SourceType Type { get; set; } public List<UserLibrary> Branches { get; set; } } Each Consortium has a list of UserLibrary's associated with it, and that class looks like this : public class UserLibrary { public string LibraryId { get; set; } public string RetailerId {get; set;} public string UserId { get; set; } public string Name { get; set; } public DateTime CreatedAt { get; set; } } I have a method which will allow the user to remove a library from one of their consortium (note: There may be many branches associated to the consortium). However, I'm only being supplied a LibraryId, so I'm forced to traverse their list of Consortium, find which one contains the given id, then iterate over the branches and remove the one that matches the id. Here is how I'm currently accomplishing this : // Get the current list of consortiums var user = _mediator.Send(new GetUserProfileCommand { UserProfileId = _principle.UserProfileId }); var userConsortia = user.SavedConsortia; // the consortium to remove the library from var branchToRemove = _libraryService.GetLibrary(id); var consortRemove = new UserConsortium(); foreach (var userConsortium in userConsortia) { if (userConsortium.Branches.FirstOrDefault(c => string.Equals(c.LibraryId, id, StringComparison.OrdinalIgnoreCase)) != null) { consortRemove = userConsortium; } } // if the consortium id is null, something is f* if (consortRemove.Id == null) { return new JsonDotNetResult(HttpStatusCode.BadRequest); } // first remove the consortia userConsortia.Remove(consortRemove); // remove the branch from the consortium consortRemove.Branches.RemoveAll(ul => string.Equals(ul.LibraryId, id, StringComparison.OrdinalIgnoreCase)); // add it back in without the branch userConsortia.Add(consortRemove); Question : Is there a LINQ expression I'm missing here that can help me consolidate this logic, or is there a better way of doing this?

  Read the article

• gcc optimization? bug? and its practial implication to project

  - by kumar_m_kiran

  Hi All, My questions are divided into three parts Question 1 Consider the below code, #include <iostream> using namespace std; int main( int argc, char *argv[]) { const int v = 50; int i = 0X7FFFFFFF; cout<<(i + v)<<endl; if ( i + v < i ) { cout<<"Number is negative"<<endl; } else { cout<<"Number is positive"<<endl; } return 0; } No specific compiler optimisation options are used or the O's flag is used. It is basic compilation command g++ -o test main.cpp is used to form the executable. The seemingly very simple code, has odd behaviour in SUSE 64 bit OS, gcc version 4.1.2. The expected output is "Number is negative", instead only in SUSE 64 bit OS, the output would be "Number is positive". After some amount of analysis and doing a 'disass' of the code, I find that the compiler optimises in the below format - Since i is same on both sides of comparison, it cannot be changed in the same expression, remove 'i' from the equation. Now, the comparison leads to if ( v < 0 ), where v is a constant positive, So during compilation itself, the else part cout function address is added to the register. No cmp/jmp instructions can be found. I see that the behaviour is only in gcc 4.1.2 SUSE 10. When tried in AIX 5.1/5.3 and HP IA64, the result is as expected. Is the above optimisation valid? Or, is using the overflow mechanism for int not a valid use case? Question 2 Now when I change the conditional statement from if (i + v < i) to if ( (i + v) < i ) even then, the behaviour is same, this atleast I would personally disagree, since additional braces are provided, I expect the compiler to create a temporary built-in type variable and them compare, thus nullify the optimisation. Question 3 Suppose I have a huge code base, an I migrate my compiler version, such bug/optimisation can cause havoc in my system behaviour. Ofcourse from business perspective, it is very ineffective to test all lines of code again just because of compiler upgradation. I think for all practical purpose, these kinds of error are very difficult to catch (during upgradation) and invariably will be leaked to production site. Can anyone suggest any possible way to ensure to ensure that these kind of bug/optimization does not have any impact on my existing system/code base? PS : When the const for v is removed from the code, then optimization is not done by the compiler. I believe, it is perfectly fine to use overflow mechanism to find if the variable is from MAX - 50 value (in my case).

  Read the article

• Why my :hover aren't working?

  - by user1628488

  I have am nav, and when i hover some elements, the submenu should be displayed 'block', but this dont work. See <!doctype html> <html lang="pt-br"> <head> <meta charset="utf-8" /> <meta name="robots" content="noindex, nofollow" /> <meta name="generator" content="Notepad++" /> <meta name="author" content="Erick Ribeiro" /> <meta http-equiv="refresh" content="60" /> <title>Mozilla Firefox</title> <style type="text/css"> *{ font-family: calibri; } #menu { float: left; } .submenu { margin-top: 26px; padding: 10px; border: solid 1px rgb(224, 224, 224); background: rgb(254, 254, 254); color: rgb(0, 128, 224); border-radius: 0 0 4px 4px; } #menuHome:hover ~ #submenuControle { display: block; opacity: 0; color: red; } #submenuHome { display: none; opacity: 0; } #submenuControle { display: block; opacity: 1; } #submenuGestão { display: none; opacity: 0; } #submenuRL { display: none; opacity: 0; } #submenuSI { display: none; opacity: 0; } ul { float: left; list-style-type: none; padding: 0; margin: 0; } li { display: inline; float:left; } .primeiroItem { border: solid rgb(224, 224, 224); border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-radius: 4px 0 0 4px; } .naoPrimeiroItem { border: solid rgb(224, 224, 224); border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 0; } .ultimoItem { border: solid rgb(224, 224, 224); border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 0; border-radius: 0 4px 4px 0; } a { text-decoration:none; padding: 8px; border: solid 1px; color: rgb(0, 0, 0); background: rgb(240,240, 240); } a:visited { color: rgb(0, 0, 0); } </style> <script type="text/javascript"> </script> </head> <body> <nav id="menu"> <ul> <li><a id="menuHome" class="primeiroItem" href="#">Home</a></li> <li><a id="menuControle" class="naoPrimeiroItem" href="#">Controle</a></li> <li><a id="menuGestao" class="naoPrimeiroItem" href="#">Gestão</a></li> <li><a id="menuRL" class="naoPrimeiroItem" href="#">Relatórios e Listas</a></li> <li><a id="menuSI" class="ultimoItem" href="#">Sistema Informação</a></li> </ul> <div id="submenuHome" class="submenu"> </div> <div id="submenuControle" class="submenu"> BSC Comunicação Treinamento Documentos Controle de Acesso </div> <div id="submenuGestão" class="submenu"> ASV Treinamento Suprimentos Chamados</div> <div id="submenuRL" class="submenu"> Listas Relatórios </div> <div id="submenuSI" class="submenu"> </div> </nav> </body> </html>

  Read the article

• When transactionManager is not named "transactionManager" ...

  - by smallufo

  I am trying Spring 3(.0.2.RELEASE) and JPA2 and Hibernate 3.5.1-Final... One thing upsets me is that spring seems only accept a transaction Manager named "transactionManager" If I don't name it "transactionManager" , Spring will throws NoSuchBeanDefinitionException: No bean named 'transactionManager' is defined. Here is my config : <context:component-scan base-package="destiny.data.mining"/> <context:annotation-config/> <bean id="miningEntityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="mining"/> </bean> <bean id="miningTransactionManager" class="org.springframework.orm.jpa.JpaTransactionManager" > <property name="entityManagerFactory" ref="miningEntityManagerFactory"/> </bean> <tx:advice id="txAdviceMining" transaction-manager="miningTransactionManager"> <tx:attributes> <tx:method name="get*" read-only="true"/> <tx:method name="save*" propagation="REQUIRED"/> <tx:method name="update*" propagation="REQUIRED"/> <tx:method name="delete*" propagation="REQUIRED"/> <tx:method name="*" propagation="SUPPORTS" read-only="true"/> </tx:attributes> </tx:advice> <aop:config> <aop:pointcut id="methods" expression="execution(* destiny.utils.AbstractDao+.*(..))"/> <aop:advisor advice-ref="txAdviceMining" pointcut-ref="methods"/> </aop:config> <tx:annotation-driven transaction-manager="miningTransactionManager"/> In this config , an Entity Manager Factory is not necessarily named "entityManagerFactory" , and "txAdvice" is not necessarily named "txAdvice" , either. But I don't know why on earth Spring requires a transaction manager named "transactionManager" ? Is there any way not to name a transaction manager "transactionManager" ? (I'm running multiple spring config files , so I try my best to avoid name-conflicting) test code : @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations={"classpath:mining.xml"}) public class MiningPersonDaoTest { @Inject private EntityManagerFactory miningEntityManagerFactory; @Inject private MiningPersonDao miningPersonDao; @Transactional @Test public void testUpdate() { MiningPerson p = miningPersonDao.get(42L); p.setLocationName("OOXX"); miningPersonDao.update(p); System.out.println(p); } } ii

  Read the article

• How to manually (bitwise) perform (float)x? (homework)

  - by Silver

  Now, here is the function header of the function I'm supposed to implement: /* * float_from_int - Return bit-level equivalent of expression (float) x * Result is returned as unsigned int, but * it is to be interpreted as the bit-level representation of a * single-precision floating point values. * Legal ops: Any integer/unsigned operations incl. ||, &&. also if, while * Max ops: 30 * Rating: 4 */ unsigned float_from_int(int x) { ... } We aren't allowed to do float operations, or any kind of casting. Now I tried to implement the first algorithm given at this site: http://locklessinc.com/articles/i2f/ Here's my code: unsigned float_from_int(int x) { // grab sign bit int xIsNegative = 0; int absValOfX = x; if(x < 0){ xIsNegative = 1; absValOfX = -x; } // zero case if(x == 0){ return 0; } //int shiftsNeeded = 0; /*while(){ shiftsNeeded++; }*/ unsigned I2F_MAX_BITS = 15; unsigned I2F_MAX_INPUT = ((1 << I2F_MAX_BITS) - 1); unsigned I2F_SHIFT = (24 - I2F_MAX_BITS); unsigned result, i, exponent, fraction; if ((absValOfX & I2F_MAX_INPUT) == 0) result = 0; else { exponent = 126 + I2F_MAX_BITS; fraction = (absValOfX & I2F_MAX_INPUT) << I2F_SHIFT; i = 0; while(i < I2F_MAX_BITS) { if (fraction & 0x800000) break; else { fraction = fraction << 1; exponent = exponent - 1; } i++; } result = (xIsNegative << 31) | exponent << 23 | (fraction & 0x7fffff); } return result; } But it didn't work (see test error below): Test float_from_int(-2147483648[0x80000000]) failed... ...Gives 0[0x0]. Should be -822083584[0xcf000000] 4 4 0 float_times_four I don't know where to go from here. How should I go about parsing the float from this int?

  Read the article

• Jscrollpane causese text to disappear on internet explorer

  - by Crippletoe

  Hello all, in my current site, i am using the new Jscrollpane in order to generate a scrollbar for a menu (not my descision but the designer's descision so i dont wanna get into how 90's that all looks like..). my menu is based on a <UL> the <li> elements inside it have the attribute "text-align: right;". my problem that on IE alone the menu text doesnt show when i apply the ScrollPane to the menu. when i delete the ScrollPane function from my code- the menu re-appears. i checked the page with "microsoft Expression" DOM inspector in order to examine how IE sees my code and i can see the <li> elements there, only the text inside them is missing. when i disable the "text-align: right;" for the <li> in my CSS, the text shows again. i suspect this has something to do with the jScrollPane's containing which is relatively aligned but i cannot be sure.. can anyone suggest some fix for this problem? a link to a page where you can see the problem is here: http://kaplanoland.com/index.php?option=com_content&view=article&id=2&Itemid=12 the problematic menu is on the right side of the page. on every browser but IE you can see the text. only on IE not. my CSS code for that menu (not including the jScrollPane CSS) is here: div#menu2{ position: absolute; top: 123px; right: 36px; width: 330px; height: 150px; } div#menu2_scroll{ /*the actual scroller*/ height: 150px; } div#menu2 div#menu2_contain{ } div#menu2 li{ text-align: right; } div#menu2 li span{ line-height: 18px; } div#menu2 a:link, div#menu2 a:visited{ color: #808285 ; font-family: Arial, Helvetica, sans-serif ; font-size: 12px ; } div#menu2 a:hover, div#menu2 li#current a{ color: #000000 ; font-family: Arial, Helvetica, sans-serif ; font-size: 12px ; } div#menu2 span.separator{ display: block; padding-top: 12px; padding-bottom: 40px; font-family: Arial, Helvetica, sans-serif; font-size: 12px; font-weight: bold; color: #000000; } div#menu2 span.separator span { padding-top: 12px; border-top-width: 1px; border-top-style: solid; border-top-color: #808285; } thank you all so much.

  Read the article

• C++ Template const char array to int

  - by Levi Schuck

  So, I'm wishing to be able to have a static const compile time struct that holds some value based on a string by using templates. I only desire up to four characters. I know that the type of 'abcd' is int, and so is 'ab','abc', and although 'a' is of type char, it works out for a template<int v> struct What I wish to do is take sizes of 2,3,4,5 of some const char, "abcd" and have the same functionality as if they used 'abcd'. Note that I do not mean 1,2,3, or 4 because I expect the null terminator. cout << typeid("abcd").name() << endl; tells me that the type for this hard coded string is char const [5], which includes the null terminator on the end. I understand that I will need to twiddle the values as characters, so they are represented as an integer. I cannot use constexpr since VS10 does not support it (VS11 doesn't either..) So, for example with somewhere this template defined, and later the last line template <int v> struct something { static const int value = v; }; //Eventually in some method cout << typeid(something<'abcd'>::value).name() << endl; works just fine. I've tried template<char v[5]> struct something2 { static const int value = v[0]; } template<char const v[5]> struct something2 { static const int value = v[0]; } template<const char v[5]> struct something2 { static const int value = v[0]; } All of them build individually, though when I throw in my test, cout << typeid(something2<"abcd">::value).name() << endl; I get 'something2' : invalid expression as a template argument for 'v' 'something2' : use of class template requires template argument list Is this not feasible or am I misunderstanding something?

  Read the article

• Spring Framework 3.0.5 MVC Issue

  - by user578923

  I know that this may be absolutely dumb but for the life of me I cannot figure out why I'm getting these errors in my Spring Project, it is basically from the MVC tutorial with a few modifications. This is the error I get when running my tomcat server. `Caused by: java.lang.NoClassDefFoundError: org/springframework/web/servlet/mvc/SimpleFormController at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:634) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) at java.net.URLClassLoader.defineClass(URLClassLoader.java:277) at java.net.URLClassLoader.access$000(URLClassLoader.java:73) at java.net.URLClassLoader$1.run(URLClassLoader.java:212) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205) at java.lang.ClassLoader.loadClass(ClassLoader.java:321) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294) at java.lang.ClassLoader.loadClass(ClassLoader.java:266) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1581) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1511) at org.springframework.util.ClassUtils.forName(ClassUtils.java:257) at org.springframework.beans.factory.support.AbstractBeanDefinition.resolveBeanClass(AbstractBeanDefinition.java:408) at org.springframework.beans.factory.support.AbstractBeanFactory.doResolveBeanClass(AbstractBeanFactory.java:1271) at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1242) ... 54 more Caused by: java.lang.ClassNotFoundException: org.springframework.web.servlet.mvc.SimpleFormController at java.net.URLClassLoader$1.run(URLClassLoader.java:217) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205) at java.lang.ClassLoader.loadClass(ClassLoader.java:321) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294) at java.lang.ClassLoader.loadClass(ClassLoader.java:266) ... 71 more` I just cannot figure out the issue with my classpath...I would appreciate any help. Here are all the jars in my classpath. I know that the class is inside the web-servlet jar but it's not seeing it. Is there a conflict? aopalliance.jar aspectjweaver.jar commons-codec.jar commons-dbcp.jar commons-logging.jar commons-pool.jar jstl.jar org.springframework.aop-3.0.5.RELEASE.jar org.springframework.asm-3.0.5.RELEASE.jar org.springframework.aspects-3.0.5.RELEASE.jar org.springframework.beans-3.0.5.RELEASE.jar org.springframework.context.support-3.0.5.RELEASE.jar org.springframework.context-3.0.5.RELEASE.jar org.springframework.core-3.0.5.RELEASE.jar org.springframework.expression-3.0.5.RELEASE.jar org.springframework.instrument.tomcat-3.0.5.RELEASE.jar org.springframework.instrument-3.0.5.RELEASE.jar org.springframework.jdbc-3.0.5.RELEASE.jar org.springframework.jms-3.0.5.RELEASE.jar org.springframework.orm-3.0.5.RELEASE.jar org.springframework.oxm-3.0.5.RELEASE.jar org.springframework.test-3.0.5.RELEASE.jar org.springframework.transaction-3.0.5.RELEASE.jar org.springframework.web.portlet-3.0.5.RELEASE.jar org.springframework.web.servlet-3.0.5.RELEASE.jar org.springframework.web.struts-3.0.5.RELEASE.jar org.springframework.web-3.0.5.RELEASE.jar postgresql-9.0-801.jdbc3.jar servlet-api.jar spring-security-config-3.0.5.RELEASE.jar spring-security-core-3.0.5.RELEASE.jar spring-security-web-3.0.5.RELEASE.jar standard.jar

  Read the article

• Many-to-one relation exception due to closed session after loading

  - by Nick Thissen

  Hi, I am using NHibernate (version 1.2.1) for the first time so I wrote a simple test application (an ASP.NET project) that uses it. In my database I have two tables: Persons and Categories. Each person gets one category, seems easy enough. | Persons | | Categories | |--------------| |--------------| | Id (PK) | | Id (PK) | | Firstname | | CategoryName | | Lastname | | CreatedTime | | CategoryId | | UpdatedTime | | CreatedTime | | Deleted | | UpdatedTime | | Deleted | The Id, CreatedTime, UpdatedTime and Deleted attributes are a convention I use in all my tables, so I have tried to bring this fact into an additional abstraction layer. I have a project DatabaseFramework which has three important classes: Entity: an abstract class that defines these four properties. All 'entity objects' (in this case Person and Category) must inherit Entity. IEntityManager: a generic interface (type parameter as Entity) that defines methods like Load, Insert, Update, etc. NHibernateEntityManager: an implementation of this interface using NHibernate to do the loading, saving, etc. Now, the Person and Category classes are straightforward, they just define the attributes of the tables of course (keeping in mind that four of them are in the base Entity class). Since the Persons table is related to the Categories table via the CategoryId attribute, the Person class has a Category property that holds the related category. However, in my webpage, I will also need the name of this category (CategoryName), for databinding purposes for example. So I created an additional property CategoryName that returns the CategoryName property of the current Category property, or an empty string if the Category is null: Namespace Database Public Class Person Inherits DatabaseFramework.Entity Public Overridable Property Firstname As String Public Overridable Property Lastname As String Public Overridable Property Category As Category Public Overridable ReadOnly Property CategoryName As String Get Return If(Me.Category Is Nothing, _ String.Empty, _ Me.Category.CategoryName) End Get End Property End Class End Namespace I am mapping the Person class using this mapping file. The many-to-one relation was suggested by Yads in another thread: <id name="Id" column="Id" type="int" unsaved-value="0"> <generator class="identity" /> </id> <property name="CreatedTime" type="DateTime" not-null="true" /> <property name="UpdatedTime" type="DateTime" not-null="true" /> <property name="Deleted" type="Boolean" not-null="true" /> <property name="Firstname" type="String" /> <property name="Lastname" type="String" /> <many-to-one name="Category" column="CategoryId" class="NHibernateWebTest.Database.Category, NHibernateWebTest" /> (I can't get it to show the root node, this forum hides it, I don't know how to escape the html-like tags...) The final important detail is the Load method of the NHibernateEntityManager implementation. (This is in C# as it's in a different project, sorry about that). I simply open a new ISession (ISessionFactory.OpenSession) in the GetSession method and then use that to fill an EntityCollection(Of TEntity) which is just a collection inheriting System.Collections.ObjectModel.Collection(Of T). public virtual EntityCollection< TEntity Load() { using (ISession session = this.GetSession()) { var entities = session .CreateCriteria(typeof (TEntity)) .Add(Expression.Eq("Deleted", false)) .List< TEntity (); return new EntityCollection< TEntity (entities); } } (Again, I can't get it to format the code correctly, it hides the generic type parameters, probably because it reads the angled symbols as a HTML tag..? If you know how to let me do that, let me know!) Now, the idea of this Load method is that I get a fully functional collection of Persons, all their properties set to the correct values (including the Category property, and thus, the CategoryName property should return the correct name). However, it seems that is not the case. When I try to data-bind the result of this Load method to a GridView in ASP.NET, it tells me this: Property accessor 'CategoryName' on object 'NHibernateWebTest.Database.Person' threw the following exception:'Could not initialize proxy - the owning Session was closed.' The exception occurs on the DataBind method call here: public virtual void LoadGrid() { if (this.Grid == null) return; this.Grid.DataSource = this.Manager.Load(); this.Grid.DataBind(); } Well, of course the session is closed, I closed it via the using block. Isn't that the correct approach, should I keep the session open? And for how long? Can I close it after the DataBind method has been run? In each case, I'd really like my Load method to just return a functional collection of items. It seems to me that it is now only getting the Category when it is required (eg, when the GridView wants to read the CategoryName, which wants to read the Category property), but at that time the session is closed. Is that reasoning correct? How do I stop this behavior? Or shouldn't I? And what should I do otherwise? Thanks!

  Read the article

• Hibernate/Spring: getHibernateTemplate().save(...) Freezes/Hangs

  - by ashes999

  I'm using Hibernate and Spring with the DAO pattern (all Hibernate dependencies in a *DAO.java class). I have nine unit tests (JUnit) which create some business objects, save them, and perform operations on them; the objects are in a hash (so I'm reusing the same objects all the time). My JUnit setup method calls my DAO.deleteAllObjects() method which calls getSession().createSQLQuery("DELETE FROM <tablename>").executeUpdate() for my business object table (just one). One of my unit tests (#8/9) freezes. I presumed it was a database deadlock, because the Hibernate log file shows my delete statement last. However, debugging showed that it's simply HibernateTemplate.save(someObject) that's freezing. (Eclipse shows that it's freezing on HibernateTemplate.save(Object), line 694.) Also interesting to note is that running this test by itself (not in the suite of 9 tests) doesn't cause any problems. How on earth do I troubleshoot and fix this? Also, I'm using @Entity annotations, if that matters. Edit: I removed reuse of my business objects (use unique objects in every method) -- didn't make a difference (still freezes). Edit: This started trickling into other tests, too (can't run more than one test class without getting something freezing) Transaction configuration: <bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource" /> </bean> <tx:advice id="txAdvice" transaction-manager="txManager"> <!-- the transactional semantics... --> <tx:attributes> <!-- all methods starting with 'get' are read-only --> <tx:method name="get*" read-only="true" /> <tx:method name="find*" read-only="true" /> <!-- other methods use the default transaction settings (see below) --> <tx:method name="*" /> </tx:attributes> </tx:advice> <!-- my bean which is exhibiting the hanging behavior --> <aop:config> <aop:pointcut id="beanNameHere" expression="execution(* com.blah.blah.IMyDAO.*(..))" /> <aop:advisor advice-ref="txAdvice" pointcut-ref="beanNameHere" /> </aop:config>

  Read the article

< Previous Page | 223 224 225 226 227 228 229 230 231 232 233 234  | Next Page >