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  • Splitting a C++ class into files now won't compile.

    - by vgm64
    Hi. I am teaching myself to write classes in C++ but can't seem to get the compilation to go through. If you can help me figure out not just how, but why, it would be greatly appreciated. Thank you in advance! Here are my three files: make_pmt.C #include <iostream> #include "pmt.h" using namespace std; int main() { CPMT *pmt = new CPMT; pmt->SetVoltage(900); pmt->SetGain(2e6); double voltage = pmt->GetVoltage(); double gain= pmt->GetGain(); cout << "The voltage is " << voltage << " and the gain is " << gain << "." <<endl; return 0; } pmt.C #include "pmt.h" using namespace std; class CPMT { double gain, voltage; public: double GetGain() {return gain;} double GetVoltage() {return voltage;} void SetGain(double g) {gain=g;} void SetVoltage(double v) {voltage=v;} }; pmt.h #ifndef PMT_H #define PMT_H 1 using namespace std; class CPMT { double gain, voltage; public: double GetGain(); double GetVoltage(); void SetGain(double g); void SetVoltage(double v); }; #endif And for reference, I get a linker error (right?): Undefined symbols: "CPMT::GetVoltage()", referenced from: _main in ccoYuMbH.o "CPMT::GetGain()", referenced from: _main in ccoYuMbH.o "CPMT::SetVoltage(double)", referenced from: _main in ccoYuMbH.o "CPMT::SetGain(double)", referenced from: _main in ccoYuMbH.o ld: symbol(s) not found collect2: ld returned 1 exit status

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  • Static Analyzer says I have a leak....why?

    - by Walter
    I think this code should be fine but Static Analyzer doesn't like it. I can't figure out why and was hoping that someone could help me understand. The code works fine, the analyzer result just bugs me. Coin *tempCoin = [[Coin alloc] initalize]; self.myCoin = tempCoin; [tempCoin release]; Coin is a generic NSObject and it has an initalize method. myCoin is a property of the current view and is of type Coin. I assume it is telling me I am leaking tempCoin. In my view's .h I have set myCoin as a property with nonatomic,retain. I've tried to autorelease the code as well as this normal release but Static Analyzer continues to say: 1. Method returns an Objective-C object with a +1 retain count (owning reference) 2. Object allocated on line 97 is no longer referenced after this point and has a retain count of +1 (object leaked) Line 97 is the first line that I show.

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  • return Queryable<T> or List<T> in a Repository<T>

    - by Danny Chen
    Currently I'm building an windows application using sqlite. In the data base there is a table say User, and in my code there is a Repository<User> and a UserManager. I think it's a very common design. In the repository there is a List method: //Repository<User> class public List<User> List(where, orderby, topN parameters and etc) { //query and return } This brings a problem, if I want to do something complex in UserManager.cs: //UserManager.cs public List<User> ListUsersWithBankAccounts() { var userRep = new UserRepository(); var bankRep = new BankAccountRepository(); var result = //do something complex, say "I want the users live in NY //and have at least two bank accounts in the system } You can see, returning List<User> brings performance issue, becuase the query is executed earlier than expected. Now I need to change it to something like a IQueryable<T>: //Repository<User> class public TableQuery<User> List(where, orderby, topN parameters and etc) { //query and return } TableQuery<T> is part of the sqlite driver, which is almost equals to IQueryable<T> in EF, which provides a query and won't execute it immediately. But now the problem is: in UserManager.cs, it doesn't know what is a TableQuery<T>, I need to add new reference and import namespaces like using SQLite.Query in the business layer project. It really brings bad code feeling. Why should my business layer know the details of the database? why should the business layer know what's SQLite? What's the correct design then?

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  • Eclipse BIRT - Unnecessary inline style with external CSS when rendering HTML

    - by Etienne
    Hello! I am designing a report using external CSS with BIRT 2.5. When BIRT renders the html report, it creates copies of each external style to inline styles (name style_x) in the resulting html. The report.design contains: <list-property name="cssStyleSheets"> <structure> <property name="fileName">… mycss.css</property> <property name="externalCssURI"> http://.../mycss.css </property> </structure> </list-property> The resulting html contains: <style type="text/css"> .style_0 {…} .style_1 {…} …. </style> <link rel="stylesheet" type="text/css" href="http://.../mycss.css"></link> For each reference of my styles, the rendered html elements use both styles usually like this: <div class="style_x myclass" …. > …. </div> Is there any way to get rid of the useless inline styles when rendering html?

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  • How to pass data to a C++0x lambda function that will run in a different thread?

    - by Dimitri C.
    In our company we've written a library function to call a function asynchronously in a separate thread. It works using a combination of inheritance and template magic. The client code looks as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, &DemoThread::SomeFunction, stringToPassByValue); Since the introduction of lambda functions I'd like to use it in combination with lambda functions. I'd like to write the following client code: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=]() { const std::string someCopy = stringToPassByValue; }); Now, with the Visual C++ 2010 this code doesn't work. What happens is that the stringToPassByValue is not copied. Instead the "capture by value" feature passes the data by reference. The result is that if the function is executed after stringToPassByValue has gone out of scope, the application crashes as its destructor is called already. So I wonder: is it possible to pass data to a lambda function as a copy? Note: One possible solution would be to modify our framework to pass the data in the lambda parameter declaration list, as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=](const std::string stringPassedByValue) { const std::string someCopy = stringPassedByValue; } , stringToPassByValue); However, this solution is so verbose that our original function pointer solution is both shorter and easier to read. Update: The full implementation of AsyncCall is too big to post here. In short, what happens is that the AsyncCall template function instantiates a template class holding the lambda function. This class is derived from a base class that contains a virtual Execute() function, and upon an AsyncCall() call, the function call class is put on a call queue. A different thread then executes the queued calls by calling the virtual Execute() function, which is polymorphically dispatched to the template class which then executes the lambda function.

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  • C#; On casting to the SAME class that came from another assembly

    - by G. Stoynev
    For complete separation/decoupling, I've implemented a DAL in an assebly that is simply being copied over via post-build event to the website BIN folder. The website then on Application Start loads that assembly via System.Reflection.Assembly.LoadFile. Again, using reflection, I construct a couple of instances from classes in that assembly. I then store a reference to these instances in the session (HttpContext.Current.Items) Later, when I try to get the object stored in the session, I am not able to cast them to their own types (was trying interfaces initially, but for debugging tried to cast to THEIR OWN TYPES), getting this error: [A]DAL_QSYSCamper.NHibernateSessionBuilder cannot be cast to [B] DAL_QSYSCamper.NHibernateSessionBuilder. Type A originates from 'DAL_QSYSCamper, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' in the context 'Default' at location 'C:\Users\dull.anomal\AppData\Local\Temp\Temporary ASP.NET Files\root\ad6e8bff\70fa2384\assembly\dl3\aaf7a5b0\84f01b09_b10acb01\DAL_QSYSCamper.DLL'. Type B originates from 'DAL_QSYSCamper, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' in the context 'LoadNeither' at location 'C:\Users\dull.anomal\Documents\Projects\QSYS\Deleteme\UI\MVCClient\bin\DAL_QSYSCa mper.DLL'. This is happening while debugging in VS - VS manages to stop into the source DAL project even though I've loaded from assembly and the project is not refferenced by the website project (they're both in the solution). I do understand the error, but I don't understand how and why the assembly is being used/loaded from two locations - I only load it once from the file and there's no referrence to the project. Should mention that I also use Windsor for DI. The object that tries to extract the object from the session is A) from a class from that DAL assembly; B) is injected into a website class by Windsor. I will work on adding some sample code to this question, but wanted to put it out in case it's obvious what I do wrong.

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  • ASP.NET MVC4: How do I keep from having multiple identical results in my lookup tables

    - by sehummel
    I'm new to ASP.NET so this may be an easy question. I'm seeding my database with several rows of dummy data. Here is one of my rows: new Software { Title = "Microsoft Office", Version = "2012", SerialNumber = "12346231434543", Platform = "PC", Notes = "Macs really rock!", PurchaseDate = "2011-12-04", Suite = true, SubscriptionEndDate = null, SeatCount = 0, SoftwareTypes = new List<SoftwareType> { new SoftwareType { Type="Suite" }}, Locations = new List<Location> { new Location { LocationName = "Paradise" }}, Publishers = new List<SoftwarePublisher> { new SoftwarePublisher { Publisher = "Microsoft" }}} But when I do this, a new row is created for each location, with the LocationName being set in each row like this. We only have two locations. How do I get it to create a LocationID property for the Software class and in my Locations class. Here is my Location class: public class Location { public int Id { get; set; } [Required] [StringLength(20)] public string LocationName { get; set; } public virtual Software Software { get; set; } } I have this line in my Software class to reference this table: public virtual List<Location> Locations { get; set; } Again, what I want when I am done is a Locations table with two entries, and a LocationID field in my Software table. How do I do this?

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  • Updating UI objects in windows forms

    - by P a u l
    Pre .net I was using MFC, ON_UPDATE_COMMAND_UI, and the CCmdUI class to update the state of my windows UI. From the older MFC/Win32 reference: Typically, menu items and toolbar buttons have more than one state. For example, a menu item is grayed (dimmed) if it is unavailable in the present context. Menu items can also be checked or unchecked. A toolbar button can also be disabled if unavailable, or it can be checked. Who updates the state of these items as program conditions change? Logically, if a menu item generates a command that is handled by, say, a document, it makes sense to have the document update the menu item. The document probably contains the information on which the update is based. If a command has multiple user-interface objects (perhaps a menu item and a toolbar button), both are routed to the same handler function. This encapsulates your user-interface update code for all of the equivalent user-interface objects in a single place. The framework provides a convenient interface for automatically updating user-interface objects. You can choose to do the updating in some other way, but the interface provided is efficient and easy to use. What is the guidance for .net Windows Forms? I am using an Application.Idle handler in the main form but am not sure this is the best way to do this. About the time I put all my UI updates in the Idle event handler my app started to show some performance problems, and I don't have the metrics to track this down yet. Not sure if it's related.

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  • NHibernate many-to-many mapping

    - by Scozzard
    Hi, I am having an issue with many-to-many mapping using NHibernate. Basically I have 2 classes in my object model (Scenario and Skill) mapping to three tables in my database (Scenario, Skill and ScenarioSkill). The ScenarioSkills table just holds the IDs of the SKill and Scenario table (SkillID, ScenarioID). In the object model a Scenario has a couple of general properties and a list of associated skills (IList) that is obtained from the ScenarioSkills table. There is no associated IList of Scenarios for the Skill object. The mapping from Scenario and Skill to ScenarioSkill is a many-to-many relationship: Scenario * --- * ScenarioSkill * --- * Skill I have mapped out the lists as bags as I believe this is the best option to use from what I have read. The mappings are as follows: Within the Scenario class <bag name="Skills" table="ScenarioSkills"> <key column="ScenarioID" foreign-key="FK_ScenarioSkill_ScenarioID"/> <many-to-many class="Domain.Skill, Domain" column="SkillID" /> </bag> And within the Skill class <bag name="Scenarios" table="ScenarioSkills" inverse="true" access="noop" cascade="all"> <key column="SkillID" foreign-key="FK_ScenarioSkill_SkillID" /> <many-to-many class="Domain.Scenario, Domain" column="ScenarioID" /> </bag> Everything works fine, except when I try to delete a skill, it cannot do so as there is a reference constraint on the SkillID column of the ScenarioSkill table. Can anyone help me? I am using NHibernate 2 on an C# asp.net 3.5 web application solution.

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  • QT NOOB: Add action handler for multiple objects of same type.

    - by what
    I have a simple QT application with 10 radio buttons with names radio_1 through radio_10. It is a ui called Selector, and is part of a class called TimeSelector In my header file for this design, i have this: //! [1] class TimeSelector : public QWidget { Q_OBJECT public: TimeSelector(QWidget *parent = 0); private slots: //void on_inputSpinBox1_valueChanged(int value); //void on_inputSpinBox2_valueChanged(int value); private: Ui::Selector ui; }; //! [1] the commented out void_on_inputSpinBox1_valueChanged(int value) is from the tutorial for the simple calculator. I know i can do: void on_radio_1_valueChanged(int value); but I would need 10 functions. I want to be able to make one function that works for everything, and lets me pass in maybe a name of the radio button that called it, or a reference to the radio button so i can work with it and determine who it was. I am very new to QT but this seems like it should be very basic and doable, thanks.

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  • Setting up isolated COM for multiple projects.

    - by Praneeth
    My solution consists of multiple projects all of which out type class library except one whose output type is windows application. The application references all the other projects. I also have a COM component which is referenced by some of the projects and the application also. I can setup the regfree COM by changing the Isolated property of the referenced COM component in visual studio to TRUE. The solution builds successfully and I can see the manifest file generated for that particular assembly or application. Now, my question is that do I need to do this for all the projects which reference the COM component? If yes, then I know that i cannot set the Isolated property to TRUE on more than one project(gives a build error) so how do I workaround this? I am relatively new to .net and don't know much regfree COM(i assume what i am doing IS regfree COM?). Any help I can get on this issue is greatly appreciated. Thanks. I am currently using VS 2008.

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  • Compilation problem in the standard x86_64 libraries

    - by user350282
    Hi everyone, I am having trouble compiling a program I have written. I have two different files with the same includes but only one generates the following error when compiled with g++ /usr/lib/gcc/x86_64-linux-gnu/4.4.1/../../../../lib/crt1.o: In function `_start': /build/buildd/eglibc-2.10.1/csu/../sysdeps/x86_64/elf/start.S:109: undefined reference to `main' collect2: ld returned 1 exit status The files I am including in my header are as follows: #include <google/sparse_hash_map> using google::sparse_hash_map; #include <ext/hash_map> #include <math.h> #include <iostream> #include <queue> #include <vector> #include <stack> using std::priority_queue; using std::stack; using std::vector; using __gnu_cxx::hash_map; using __gnu_cxx::hash; using namespace std; Searching the internet for those two lines hasn't resulted in anything to help me. I would be very grateful for any advice. Thank you

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  • WPF or Silverlight Learning Resources for Business Applications

    - by Refracted Paladin
    I am the only developer at a non-profit organization(~200 employees) where we are a M$ shop and 90% of the things I develop are specific to our company and are internal only. I am given a lot of latitude on how I accomplish my goals so using new technologies is in my best interest. So far I have developed all winform & asp.net applications. I would now like to focus on XAML driven development(WPF & Silverlight) and would like your help. I am subscribed to numerous Silverlight blogs and I have went through a few good tutorials however, I would really appreciate a GOOD SOLID book in my hands going forward. I prefer learning books versus reference books and I REALLY would like one from a Business standpoint as well. Shameless, self-promoting is welcomed if you happen to be an author or reviewer for one that meets my criteria. I would, however, prefer that recomendations were based on first-hand experience(no, 'my friend as this awesome book he told me about', please). Though, I don't mind un-released books if say they are an updated version of an existing. disclaimer -- I know there are an insane amount of Book posts here(SO) but none I believe for my specific need. If there is and I missed it I apologize.

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  • How can I use a compound condition in a join in Linq?

    - by Gary McGill
    Let's say I have a Customer table which has a PrimaryContactId field and a SecondaryContactId field. Both of these are foreign keys that reference the Contact table. For any given customer, either one or two contacts may be stored. In other words, PrimaryContactId can never be NULL, but SecondaryContactId can be NULL. If I drop my Customer and Contact tables onto the "Linq to SQL Classes" design surface, the class builder will spot the two FK relationships from the Customer table to the Contact table, and so the generated Customer class will have a Contact field and a Contact1 field (which I can rename to PrimaryContact and SecondaryContact to avoid confusion). Now suppose that I want to get details of all the contacts for a given set of customers. If there was always exactly one contact then I could write something like: from customer in customers join contact in contacts on customer.PrimaryContactId equals contact.id select ... ...which would be translated into something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id But, because I want to join on both the contact fields, I want the SQL to look something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id OR Customer.SecondSalesPersonId = Contact.id How can I write a Linq expression to do that?

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  • Problem with generic list and extension method(C#3.0)

    - by Newbie
    I have an issue. I am making an extension class for a Collection and it is generic.. like public static class ListExtensions { public static ICollection<T> Search<T>(this ICollection<T> collection, string stringToSearch) { ICollection<T> t1=null; foreach (T t in collection) { Type k = t.GetType(); PropertyInfo pi = k.GetProperty("Name"); if (pi.GetValue(t,null).Equals(stringToSearch)) { t1.Add(t); } } return t1; } } But I cannot add items to t1 as it is declared null. Error: object reference not set to an instance of the object. I am calling the method like List<TestClass> listTC = new List<TestClass>(); listTC.Add(new TestClass { Name = "Ishu", Age = 21 }); listTC.Add(new TestClass { Name = "Vivek", Age = 40 }); listTC.Add(new TestClass { Name = "some one else", Age = 12 }); listTC.Search("Ishu"); And the test class is public class TestClass { public string Name { get; set; } public int Age { get; set; } } Using : (C#3.0) & Framework - 3.5 Thanks

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  • Is this overly clever or unsafe?

    - by Liberalkid
    I was working on some code recently and decided to work on my operator overloading in c++, because I've never really implemented it before. So I overloaded the comparison operators for my matrix class using a compare function that returned 0 if LHS was less than RHS, 1 if LHS was greater than RHS and 2 if they were equal. Then I exploited the properties of logical not in c++ on integers, to get all of my compares in one line: inline bool Matrix::operator<(Matrix &RHS){ return ! (compare(*this,RHS)); } inline bool Matrix::operator>(Matrix &RHS){ return ! (compare((*this),RHS)-1); } inline bool Matrix::operator>=(Matrix &RHS){ return compare((*this),RHS); } inline bool Matrix::operator<=(Matrix &RHS){ return compare((*this),RHS)-1; } inline bool Matrix::operator!=(Matrix &RHS){ return compare((*this),RHS)-2; } inline bool Matrix::operator==(Matrix &RHS){ return !(compare((*this),RHS)-2); } Obviously I should be passing RHS as a const, I'm just probably not going to use this matrix class again and I didn't feel like writing another function that wasn't a reference to get the array index values solely for the comparator operation.

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  • WPF & Linq To SQL binding ComboBox to foreign key

    - by ZeroDelta
    I'm having trouble binding a ComboBox to a foreign key in WPF using Linq To SQL. It works fine when displaying records, but if I change the selection on the ComboBox, that change does not seem to affect the property to which it is bound. My SQL Server Compact file has three tables: Players (PK is PlayerID), Events (PK is EventID), and Matches (PK is MatchID). Matches has FKs for the the other two, so that a match is associated with a player and an event. My window for editing a match uses a ComboBox to select the Event, and the ItemsSource is set to the result of a LINQ query to pull all of the Events. And of course the user should be able to select the Event based on EventName, not EventID. Here's the XAML: <ComboBox x:Name="cboEvent" DisplayMemberPath="EventName" SelectedValuePath="EventID" SelectedValue="{Binding Path=EventID, UpdateSourceTrigger=PropertyChanged}" /> And some code-behind from the Loaded event handler: var evt = from ev in db.Events orderby ev.EventName select ev; cboEvent.ItemsSource = evt.ToList(); var mtch = from m in db.Matches where m.PlayerID == ((Player)playerView.CurrentItem).PlayerID select m; matchView = (CollectionView)CollectionViewSource.GetDefaultView(mtch); this.DataContext = matchView; When displaying matches, this works fine--I can navigate from one match to the next and the EventName is shown correctly. However, if I select a new Event via this ComboBox, the CurrentItem of the CollectionView doesn't seem to change. I feel like I'm missing something stupid! Note: the Player is selected via a ListBox, and that selection filters the matches displayed--this seems to be working fine, so I didn't include that code. That is the reason for the "PlayerID" reference in the LINQ query

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  • Why does my simple event handling example not work?

    - by njreed
    I am trying to make a simple event handler. (Note, I'm not trying to implement a full-blown publish/subscribe model; I'm just interested in why my example doesn't work as I think it should) var myObj = (function () { var private = "X"; function triggerEvent(eventName) { if (this[eventName]) { this[eventName](); } } // Setter / Getter function getProp() { return private; } function setProp(value) { private = value; triggerEvent("onPropChange"); } // Public API return { // Events "onPropChange": null, // Fires when prop value is changed // Methods "getProp": getProp, "setProp": setProp }; })(); // Now set event handler myObj.onPropChange = function () { alert("You changed the property!"); }; myObj.setProp("Z"); // --> Nothing happens. Wrong // Why doesn't my alert show? I set the onPropChange property of my object to a simpler handler function but it is not being fired. I have debugged this and it seems that in triggerEvent the variable this is referencing the global window object. I thought it should reference myObj (which is what I need). Can someone explain the error in my thinking and how I correct this? Help much appreciated. jsFiddle here

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  • PHP DELETE immediately after select

    - by teehoo
    I have a PHP server script that SELECTs some data from a MySQL database. As soon as I have the result from mysql_query and mysql_fetch_assoc stored in my own local variables, I want to delete the row I just selected. The problem with this approach is that it seems that PHP has done pass-by-reference to my local variables instead of pass-by-value, and my local variables become undefined after the delete command. Is there anyway to get around this? Here is my code: $query="SELECT id, peerID, name FROM names WHERE peer = $userID AND docID = '$docID' AND seqNo = $nid"; $result = mysql_query($query); if (!$result) self::logError("FAIL:1 getUsersNamesUpdate() query: ".$query."\n"); if (mysql_num_rows($result) == 0) return array(); $row = mysql_fetch_assoc($result); $result = array(); $result["id"] = $row["id"]; $result["peerID"] = $row["peerID"]; $result["name"] = $row["name"]; $query="DELETE FROM names WHERE id = $result[id];"; $result = mysql_query($query); if (!$result) self::logError("FAIL:2 getUsersNamesUpdate() query: ".$query."\n"); return $result;

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  • Batch insert mode with hibernate and oracle: seems to be dropping back to slow mode silently

    - by Chris
    I'm trying to get a batch insert working with Hibernate into Oracle, according to what i've read here: http://docs.jboss.org/hibernate/core/3.3/reference/en/html/batch.html , but with my benchmarking it doesn't seem any faster than before. Can anyone suggest a way to prove whether hibernate is using batch mode or not? I hear that there are numerous reasons why it may silently drop into normal mode (eg associations and generated ids) so is there some way to find out why it has gone non-batch? My hibernate.cfg.xml contains this line which i believe is all i need to enable batch mode: <property name="jdbc.batch_size">50</property> My insert code looks like this: List<LogEntry> entries = ..a list of 100 LogEntry data classes... Session sess = sessionFactory.getCurrentSession(); for(LogEntry e : entries) { sess.save(e); } sess.flush(); sess.clear(); My 'logentry' class has no associations, the only interesting field is the id: @Entity @Table(name="log_entries") public class LogEntry { @Id @GeneratedValue public Long id; ..other fields - strings and ints... However, since it is oracle, i believe the @GeneratedValue will use the sequence generator. And i believe that only the 'identity' generator will stop bulk inserts. So if anyone can explain why it isn't running in batch mode, or how i can find out for sure if it is or isn't in batch mode, or find out why hibernate is silently dropping back to slow mode, i'd be most grateful. Thanks

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  • Issues regarding playing audio files in a JME midlet.

    - by Northernen
    I am making a midlet which is to be used to play out local audio files. It is obviously not working. I am getting a null reference on the "is" variable, in the code snippet shown below. 1. try{ 2. System.out.println("path: " + this.getClass()); 3. InputStream is = this.getClass().getResourceAsStream("res/01Track.wav"); 4. p1=Manager.createPlayer(is, "audio"); 5. p1.realize(); 6. p1.prefetch(); 7. p1.start(); 8. } 9. catch(Exception e){ 10. System.out.println(e.getMessage()); 11. } I assume there is something wrong with the "this.getClass().getResourceAsStream("res/01Track.wav")" bit, but I can not for the life of me figure out why, and I have tried referring to the file in 20 different ways. If I printline "this.getClass()" it gives me "path: class Mp3spiller". The absolute path to "01Track.wav" is "E:\Mine dokumenter\Dokumenter\workspace_mobiljava\Mp3spiller\res\01Track.wav". Am I completely wrong in thinking that I should refer relatively to "E:\Mine dokumenter\Dokumenter\workspace_mobiljava\Mp3spiller"? If anyone could point out what I am doing wrong, I would be grateful. I have basically stolen the code from a tutorial I found online, so I would have thought it would be working.

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  • database design - empty fields

    - by imanc
    Hey, I am currently debating an issue with a guy on my dev team. He believes that empty fields are bad news. For instance, if we have a customer details table that stores data for customers from different countries, and each country has a slightly different address configuration - plus 1-2 extra fields, e.g. French customer details may also store details for entry code, and floor/level plus title fields (madamme, etc.). South Africa would have a security number. And so on. Given that we're talking about minor variances my idea is to put all of the fields into the table and use what is needed on each form. My colleague believes we should have a separate table with extra data. E.g. customer_info_fr. But this seams to totally defeat the purpose of a combined table in the first place. His argument is that empty fields / columns is bad - but I'm struggling to find justification in terms of database design principles for or against this argument and preferred solutions. Another option is a separate mini EAV table that stores extra data with parent_id, key, val fields. Or to serialise extra data into an extra_data column in the main customer_data table. I think I am confused because what I'm discussing is not covered by 3NF which is what I would typically use as a reference for how to structure data. So my question specifically: - if you have slight variances in data for each record (1-2 different fields for instance) what is the best way to proceed?

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  • Do I need to Salt and Hash a randomly generated token?

    - by wag2639
    I'm using Adam Griffiths's Authentication Library for CodeIgniter and I'm tweaking the usermodel. I came across a generate function that he uses to generate tokens. His preferred approach is to reference a value from random.org but I considered that superfluous. I'm using his fall back approach of randomly generating a 20 character long string: $length = 20; $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'; $token = ''; for ($i = 0; $i < $length; $i++) { $token .= $characters[mt_rand(0, strlen($characters)-1)]; } He then hashes this token using a salt (I'm combing code from different functions) sha1($this->CI->config->item('encryption_key').$str); I was wondering if theres any reason to to run the token through the salted hash? I've read that simply randomly generating strings was a naive way of making random passwords but is the sh1 hash and salt necessary? Note: I got my encryption_key from https://www.grc.com/passwords.htm (63 random alpha-numeric)

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  • SIlverlight Navigate: how does it work? How would you implement in f# w/o VS wizards and helpers?

    - by akaphenom
    After a nights sleep the problem can be stated more accurately as I have a 100% f# / silverlight implementation and am looking to use the built in Navigation components. C# creates page.xaml and page.xaml.cs um - ok; but what is the relationship at a fundamental level? How would I go about doing this in f#? The applcuation is loaded in the default module, and I pull the XAML in and reference it from the application object. Do I need to create instances / references to the pages from within the application object? Or set up some other page management object with the proper name value pairs? When all the Help of VS is stripped away - what are we left with? original post (for those who may be reading replies) I have a 100% silverlight 3.0 / f# 2.0 application I am wrapping my brain around. I have the base application loading correctly - and now I want to add the naigation controls to it. My page is stored as an embedded resource - but the Frame.Navigate takes a URI. I know what I have is wrong but here it is: let nav : Frame = mainGrid ? mainFrame let url = "/page1.xaml" let uri = new System.Uri(url, System.UriKind.Relative) ; nav.Navigate uri Any thoughts?

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  • Contrary to Python 3.1 Docs, hash(obj) != id(obj). So which is correct?

    - by Don O'Donnell
    The following is from the Python v3.1.2 documentation: From The Python Language Reference Section 3.3.1 Basic Customization: object.__hash__(self) ... User-defined classes have __eq__() and __hash__() methods by default; with them, all objects compare unequal (except with themselves) and x.__hash__() returns id(x). From The Glossary: hashable ... Objects which are instances of user-defined classes are hashable by default; they all compare unequal, and their hash value is their id(). This is true up through version 2.6.5: Python 2.6.5 (r265:79096, Mar 19 2010 21:48:26) ... ... >>> class C(object): pass ... >>> c = C() >>> id(c) 11335856 >>> hash(c) 11335856 But in version 3.1.2: Python 3.1.2 (r312:79149, Mar 21 2010, 00:41:52) ... ... >>> class C: pass ... >>> c = C() >>> id(c) 11893680 >>> hash(c) 743355 So which is it? Should I report a documentation bug or a program bug? And if it's a documentation bug, and the default hash() value for a user class instance is no longer the same as the id() value, then it would be interesting to know what it is or how it is calculated, and why it was changed in version 3.

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