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  • Singleton constructor question

    - by gillyb
    Hi, I created a Singleton class in c#, with a public property that I want to initialize when the Singleton is first called. This is the code I wrote : public class BL { private ISessionFactory _sessionFactory; public ISessionFactory SessionFactory { get { return _sessionFactory; } set { _sessionFactory = value; } } private BL() { SessionFactory = Dal.SessionFactory.CreateSessionFactory(); } private object thisLock = new object(); private BL _instance = null; public BL Instance { get { lock (thisLock) { if (_instance == null) { _instance = new BL(); } return _instance; } } } } As far as I know, when I address the Instance BL object in the BL class for the first time, it should load the constructor and that should initialize the SessionFactory object. But when I try : BL.Instance.SessionFactory.OpenSession(); I get a Null Reference Exception, and I see that SessionFactory is null... why?

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  • Simple WCF question.

    - by bearrito
    So I am learning WCF and I have run across an issue that I believe has to do with Instance Control/State but I am not sure. Workflow is as follows, Basic client/server paradigm. The client calls a Method RetrieveBusinessObjects(criteria) and the server calls the datalayer and then puts them in an IList on the server side. It does not return this list to the calling Client. The client would then call a method say DisplayBusinessObjects() which would retrieve the IList from the Server, serialize them, bring them across the wire and display them. If i try this using the WCFTestClient it works. If I run it from an actual client then I get back an BusinessObject[] of size 0. Which to me indicates I had no objects to return. Is that a state mgmt issue or am I missing something?

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  • ASP.NET MVC NullReferenceException when inheriting from a Base Controller

    - by rockinthesixstring
    I've got a base controller that I inherit all of my Controllers from. It's job is to basically set caching and error handling as well as check for mobile browsers. My UI works fine, but my Unit Tests are failing. Imports System.Web.Mvc <HandleError()> _ <CompressFilter()> _ <OutputCache(Duration:=30, VaryByParam:="id")> _ Public Class BaseController : Inherits System.Web.Mvc.Controller Protected Overrides Function View(ByVal viewName As String, ByVal masterName As String, ByVal model As Object) As System.Web.Mvc.ViewResult Dim ismobile As Nullable(Of Boolean) = Request.Browser.IsMobileDevice If ismobile Then Return MyBase.View(viewName, "Mobile", model) Else Return MyBase.View(viewName, "Site", model) End If End Function End Class The error I'm getting in my Unit test is on Dim ismobile As Nullable(Of Boolean) = Request.Browser.IsMobileDevice saying Object Reference Not Set To An Instance Of An Object.

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  • require_owner code to limit controller actions not recognizing current user as owner

    - by bgadoci
    I am trying to restrict access to certain actions using a before_filter which seems easy enough. Somehow the ApplicationController is not recognizing that the current_user is the owner of the user edit action. When I take the filter off the controller correctly routes the current_user to their edit view information. Here is the code. Link to call edit action from user controller (views/questions/index.html.erb): <%= link_to "Edit Profile", edit_user_path(:current) %> ApplicationController (I am only posting the code that I think is affecting this but can post the whole thing if needed). class ApplicationController < ActionController::Base def require_owner obj = instance_variable_get("@#{controller_name.singularize.camelize.underscore}") # LineItem becomes @line_item return true if current_user_is_owner?(obj) render_error_message("You must be the #{controller_name.singularize.camelize} owner to access this page", root_url) return false end end and the before_filter class UsersController < ApplicationController before_filter :require_owner, :only => [:edit, :update, :destroy] #... end I simply get the rendering of the error message from the ApplicationController#require_owner action.

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  • Problem updating through LINQtoSQL in MVC application using StructureMap, Repository Pattern and UoW

    - by matt
    I have an ASP MVC application using LINQ to SQL for data access. I am trying to use the Repository and Unit of Work patterns, with a service layer consuming the repositories and unit of work. I am experiencing a problem when attempting to perform updates on a particular repository. My application architecture is as follows: My service class: public class MyService { private IRepositoryA _RepositoryA; private IRepositoryB _RepositoryB; private IUnitOfWork _unitOfWork; public MyService(IRepositoryA ARepositoryA, IRepositoryB ARepositoryB, IUnitOfWork AUnitOfWork) { _unitOfWork = AUnitOfWork; _RepositoryA = ARepositoryA; _RepositoryB = ARepositoryB; } public PerformActionOnObject(Guid AID) { MyObject obj = _RepositoryA.GetRecords() .WithID(AID); obj.SomeProperty = "Changed to new value"; _RepositoryA.UpdateRecord(obj); _unitOfWork.Save(); } } Repository interface: public interface IRepositoryA { IQueryable<MyObject> GetRecords(); UpdateRecord(MyObject obj); } Repository LINQtoSQL implementation: public class LINQtoSQLRepositoryA : IRepositoryA { private MyDataContext _DBContext; public LINQtoSQLRepositoryA(IUnitOfWork AUnitOfWork) { _DBConext = AUnitOfWork as MyDataContext; } public IQueryable<MyObject> GetRecords() { return from records in _DBContext.MyTable select new MyObject { ID = records.ID, SomeProperty = records.SomeProperty } } public bool UpdateRecord(MyObject AObj) { MyTableRecord record = (from u in _DB.MyTable where u.ID == AObj.ID select u).SingleOrDefault(); if (record == null) { return false; } record.SomeProperty = AObj.SomePropery; return true; } } Unit of work interface: public interface IUnitOfWork { void Save(); } Unit of work implemented in data context extension. public partial class MyDataContext : DataContext, IUnitOfWork { public void Save() { SubmitChanges(); } } StructureMap registry: public class DataServiceRegistry : Registry { public DataServiceRegistry() { // Unit of work For<IUnitOfWork>() .HttpContextScoped() .TheDefault.Is.ConstructedBy(() => new MyDataContext()); // RepositoryA For<IRepositoryA>() .Singleton() .Use<LINQtoSQLRepositoryA>(); // RepositoryB For<IRepositoryB>() .Singleton() .Use<LINQtoSQLRepositoryB>(); } } My problem is that when I call PerformActionOnObject on my service object, the update never fires any SQL. I think this is because the datacontext in the UnitofWork object is different to the one in RepositoryA where the data is changed. So when the service calls Save() on it's IUnitOfWork, the underlying datacontext does not have any updated data so no update SQL is fired. Is there something I've done wrong in the StrutureMap registry setup? Or is there a more fundamental problem with the design? Many thanks.

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  • asp.net mvc crazy error

    - by bongoo
    Hi there im having a weird error which is related to an earlier post , I am checking if a file exists before downloading. This works for pdf's but not for any other type of document here is my controller action and the typical path for a pdf and a powerpoint file , the powerpoint does not work ~/Documents//FID//TestDoc//27a835a5-bf70-4599-8606-6af64b33945d/FIDClasses.pdf ~/Documents//FID//pptest//ce36e7a0-14de-41f3-8eb7-0d543c7146fe/PPttest.ppt [UnitOfWork] public ActionResult Download(int id) { Document doc = _documentRepository.GetById(id); if (doc != null) { if (System.IO.File.Exists(Server.MapPath(doc.filepath))) { _downloadService.AddDownloadsForDocument(doc.document_id, _UserService.CurrentUser().user_id); return File(doc.filepath, doc.mimetype, doc.title); } } return RedirectToAction("Index"); }

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  • GCC problem with raw double type comparisons

    - by Monomer
    I have the following bit of code, however when compiling it with GCC 4.4 with various optimization flags I get some unexpected results when its run. #include <iostream> int main() { const unsigned int cnt = 10; double lst[cnt] = { 0.0 }; const double v[4] = { 131.313, 737.373, 979.797, 731.137 }; for(unsigned int i = 0; i < cnt; ++i) { lst[i] = v[i % 4] * i; } for(unsigned int i = 0; i < cnt; ++i) { double d = v[i % 4] * i; if(lst[i] != d) { std::cout << "error @ : " << i << std::endl; return 1; } } return 0; } when compiled with: "g++ -pedantic -Wall -Werror -O1 -o test test.cpp" I get the following output: "error @ : 3" when compiled with: "g++ -pedantic -Wall -Werror -O2 -o test test.cpp" I get the following output: "error @ : 3" when compiled with: "g++ -pedantic -Wall -Werror -O3 -o test test.cpp" I get no errors when compiled with: "g++ -pedantic -Wall -Werror -o test test.cpp" I get no errors I do not believe this to be an issue related to rounding, or epsilon difference in the comparison. I've tried this with Intel v10 and MSVC 9.0 and they all seem to work as expected. I believe this should be nothing more than a bitwise compare. If I replace the if-statement with the following: if (static_cast<long long int>(lst[i]) != static_cast<long long int>(d)), and add "-Wno-long-long" I get no errors in any of the optimization modes when run. If I add std::cout << d << std::endl; before the "return 1", I get no errors in any of the optimization modes when run. Is this a bug in my code, or is there something wrong with GCC and the way it handles the double type?

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  • Using events in threads between processes - C

    - by Jamie Keeling
    Hello all! I have an application consisting of two windows, one communicates to the other and sends it a struct constaining two integers (In this case two rolls of a dice). I will be using events for the following circumstances: Process a sends data to process b, process b displays data Process a closes, in turn closing process b Process b closes a, in turn closing process a I have noticed that if the second process is constantly waiting for the first process to send data then the program will be just sat waiting, which is where the idea of implementing threads on each process occurred and I have started to implement this already. The problem i'm having is that I don't exactly have a lot of experience with threads and events so I'm not sure of the best way to actually implement what I want to do. Following is a small snippet of what I have so far in the producer application; Create thread: case IDM_FILE_ROLLDICE: { hDiceRoll = CreateThread( NULL, // lpThreadAttributes (default) 0, // dwStackSize (default) ThreadFunc(hMainWindow), // lpStartAddress NULL, // lpParameter 0, // dwCreationFlags &hDiceID // lpThreadId (returned by function) ); } break; The data being sent to the other process: DWORD WINAPI ThreadFunc(LPVOID passedHandle) { HANDLE hMainHandle = *((HANDLE*)passedHandle); WCHAR buffer[256]; LPCTSTR pBuf; LPVOID lpMsgBuf; LPVOID lpDisplayBuf; struct diceData storage; HANDLE hMapFile; DWORD dw; //Roll dice and store results in variable storage = RollDice(); hMapFile = CreateFileMapping( (HANDLE)0xFFFFFFFF, // use paging file NULL, // default security PAGE_READWRITE, // read/write access 0, // maximum object size (high-order DWORD) BUF_SIZE, // maximum object size (low-order DWORD) szName); // name of mapping object if (hMapFile == NULL) { dw = GetLastError(); MessageBox(hMainHandle,L"Could not create file mapping object",L"Error",MB_OK); return 1; } pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object FILE_MAP_ALL_ACCESS, // read/write permission 0, 0, BUF_SIZE); if (pBuf == NULL) { MessageBox(hMainHandle,L"Could not map view of file",L"Error",MB_OK); CloseHandle(hMapFile); return 1; } CopyMemory((PVOID)pBuf, &storage, (_tcslen(szMsg) * sizeof(TCHAR))); //_getch(); MessageBox(hMainHandle,L"Completed!",L"Success",MB_OK); UnmapViewOfFile(pBuf); return 0; } I'm trying to find out how I would integrate an event with the threaded code to signify to the other process that something has happened, I've seen an MSDN article on using events but it's just confused me if anything, I'm coming up on empty whilst searching on the internet too. Thanks for any help Edit: I can only use the Create/Set/Open methods for events, sorry for not mentioning it earlier.

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  • How do I stop server control attributes being HTML encoded?

    - by Billious
    I'm trying to alter the onmouseover attribute of a HyperLink server control, but when I do so the JavaScript call I'm entering gets HTML encoded. For example: linkBooks.Attributes("onmouseover") = "changeImages(""books"", ""/images/common/books-dark.png""); return true;" Gets converted to: onmouseover="changeImages(&quot;books&quot;, &quot;/images/common/books-dark.png&quot;); return true;" How do I prevent this? The same code worked fine under VS2005 and .NET 2.0, I'm currently using VS2010RC and .NET 4.0.

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  • VB.Net List.Find. Pass values to predicate

    - by Beta033
    Having a bit of trouble using the List.Find with a custom predicate i have a function that does this private function test () Dim test As Integer = keys.Find(AddressOf FindByOldKeyAndName).NewKey here's the function for the predicate Private Shared Function FindByOldKeyAndName(ByVal k As KeyObj) As Boolean If k.OldKey = currentKey.OldKey And k.KeyName = currentKey.KeyName Then Return True Else Return False End If End Function by doing it this way means i have to have a shared "currentKey" object in the class, and i know there has to be a way to pass in the values i'm interested in of CurrentKey (namely, keyname, and oldkey) ideally i'd like to call it by something like keys.Find(AddressOf FindByOldKeyAndName(Name,OldVal)) however when i do this i get compiler errors. How do i call this method and pass in the values?

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  • How to let the matcher to match the second invocation on mock?

    - by Alex Luya
    I have an interface like this public interface EventBus{ public void fireEvent(GwtEvent<?> event); } and test code(testng method) looks like this: @Test public void testFireEvent(){ EventBus mock=mock(EventBus.class); //when both Event1 and Event2 are subclasses of GwtEvent<?> mock.fireEvent(new Event1()); mock.fireEvent(new Event2()); //then verify(mock).fireEvent(argThat(new Event2Matcher())); } Event2Matcher looks like this: private class Event2Matcher extends ArgumentMatcher<Event2> { @Override public boolean matches(Object arg) { return ((Event2) arg).getSth==sth; } } But get an error indicating that: Event1 can't be cast to Event2 And obviously,the matcher matched the first invoking mock.fireEvent(new Event1()); So,the statement within matcher return ((Event2) arg).getSth==sth; Will throw out this exception.So the question is how to let verify(mock).fireEvent(argThat(new Event2Matcher())); to match the second invoking?

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  • WPF multibound textblock not updating

    - by Superstringcheese
    I want to create a program which calculates how long it will take to repeat a process a certain number of times. I've scaled this down a lot for this example. So, I have some textboxes which are bound to properties in a class: Count: <TextBox x:Name="txtCount" Text="{Binding Count, Mode=TwoWay}" Width="50"/> Days: <TextBox x:Name="txtDays" Text="{Binding Days, Mode=TwoWay}" Width="50"/> and a textblock which is multibound like so: <TextBlock x:Name="tbkTotal"> <TextBlock.Text> <MultiBinding StringFormat="Days: {0}, Count: {1}"> <Binding Path="Days" /> /* This isn't updating */ <Binding Path="Count" /> </MultiBinding> </TextBlock.Text> </TextBlock> My DataContext is set in the Window1.xaml.cs file. public Window1() { InitializeComponent(); Sample sample = new Sample(); this.DataContext = sample; } I can update the multibound textblock with the Count property just fine, but the Days property always shows 0, even though the Days input accurately reflects changes. I believe that this is because my accessors are different for Days - namely, the Set method. This class is in a different file. public class Sample : INotifyPropertyChanged { private int _count; private TimeSpan _span; public int Count { get { return _count; } set { _count = value; NotifyPropertyChanged("Count"); /* Doesn't seem to be needed, actually */ } } public TimeSpan Span { get { return _span; } } /* The idea is to provide a property for Days, Hours, Minutes, etc. as conveniences to the inputter */ public double Days { get { return _span.Days; } set { TimeSpan ts = new TimeSpan(); double val = value > 0 ? value : 0; ts = TimeSpan.FromDays(val); _span.Add(ts); NotifyPropertyChanged("Span"); /* Here I can only get it to work if I notify that Span has changed - doesn't seem to be aware that the value behind Days has changed. */ } } private void NotifyPropertyChanged(string property) { if (null != this.PropertyChanged) { PropertyChanged(this, new PropertyChangedEventArgs(property)); } } public Sample() { _count = 0; _span = new TimeSpan(); } public event PropertyChangedEventHandler PropertyChanged; }

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  • NHibernate - define where condition

    - by t.kehl
    Hi. In my application the user can defines search-conditions. He can choose a column, set an operator (equals, like, greater than, less or equal than, etc.) and give in the value. After the user clicks on a button and the application should do a search on the database with the condition. I use NHibernate and ask me now, what is the efficientest way to do this with NHibernate. Should I create a query with it like (Column=Name, Operator=Like, Value=%John%) var a = session.CreateCriteria<Customer>(); a.Add(Restrictions.Like("Name", "%John%")); return a.List<Customer>(); Or should I do this with HQL: var q = session.CreateQuery("from Customer where " + where); return q.List<Customer >(); Or is there a more bether solution? Thanks for your help. Best Regards, Thomas

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  • debug error : max must have union class struct types

    - by hcemp
    this is my code: #include <iostream> using namespace std; class Sp { private : int a;int b; public: Sp(int x=0,int y=0):a(x),b(y){}; int max(int x,int y); }; int Sp::max(int a,int b) { return (a>b?a:b);}; int main() { int q,q1; cin>>q>>q1; Sp *mm=new Sp(q,q1); cout<< mm.max(q,q1); return 0; }

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  • How to binding to bit datatype in SQL to Booleans/CheckBoxes in ASP.NET MVC 2 with DataAnnotations

    - by nvtthang
    I've got problem with binding data type boolean to checkbox in MVC 2 data annotations Here's my code sample: label> Is Hot </label> <%=Html.CheckBoxFor(model => model.isHot, new {@class="input" })%> It always raise this error message below at (model=model.isHot). Cannot convert lambda expression to delegate type 'System.Func<Framework.Models.customer,bool>' because some of the return types in the block are not implicitly convertible to the delegate return type Cannot implicitly convert type 'bool?' to 'bool'. An explicit conversion exists (are you missing a cast?) Please suggest me how can I solve this problem? Thanks in advance.

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  • why must you provide the keyword const in operator overloads

    - by numerical25
    Just curious on why a param has to be a const in operation overloading CVector& CVector::operator= (const CVector& param) { x=param.x; y=param.y; return *this; } couldn't you have easily done something like this ?? CVector& CVector::operator= (CVector& param) //no const { x=param.x; y=param.y; return *this; } Isn't when something becomes a const, it is unchangeable for the remainder of the applications life ?? How does this differ in operation overloading ???

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  • Function From C to Delphi

    - by XBasic3000
    I created a function similar below in delphi code. but it wont work. What is the proper way to convert this? char* ReadSpeechFile(char* pFileName, int *nFileSize) { char *szBuf, *pLinearPCM; int nSize; FILE* fp; //read wave data fp = fopen(pFileName, "rb"); if(fp == NULL) return NULL; fseek(fp, 0, SEEK_END); nSize = ftell(fp); //linear szBuf = (char *)calloc(nSize, sizeof(char)); fseek(fp, 0, SEEK_SET); fread(szBuf, sizeof(char), nSize, fp); fclose(fp); *nFileSize = nSize; return szBuf; }

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  • django + xmppy: send a message to two recipients

    - by Agrajag
    I'm trying to use xmpppy for sending jabber-messages from a django-website. This works entirely fine. However, the message only gets sent to the -first- of the recipients in the list. This happens when I run the following function from django, and also if I run it from an interactive python-shell. The weird part though, is that if I extract the -body- of the function and run that interactively, then all the recipients (there's just 2 at the moment) get the message. Also, I do know that the inner for-loop gets run the correct count times (2), because the print-statement does run twice, and return two different message-ids. The function looks like this: def hello_jabber(request, text): jid=xmpp.protocol.JID(settings.JABBER_ID) cl=xmpp.Client(jid.getDomain(),debug=[]) con=cl.connect() auth=cl.auth(jid.getNode(),settings.JABBER_PW,resource=jid.getResource()) for friend in settings.JABBER_FRIENDS: id=cl.send(xmpp.protocol.Message(friend,friend + ' is awesome:' + text)) print 'sent message with id ' + str(id) cl.disconnect() return render_to_response('jabber/sent.htm', locals())

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  • Value isnt being saved in the strings

    - by Raptrex
    I'm trying to make a class where I put a key and value into the put method which puts the key in the k string array and value into the v string array, however it is not being saved in the array when I do get or display. For example: put(dan,30) get(dan) returns null display returns null null 10 times. Anyone know whats wrong? public class Memory { final int INITIAL_CAPACITY = 10; String[] k = new String[INITIAL_CAPACITY]; String[] v = new String[INITIAL_CAPACITY]; int count = 0; public Memory() { count = 0; } public int size() { return count; } public void put(String key, String value) { int a = 0; boolean found = false; for (int i = 0; i < k.length; i++) { //System.out.println("key is " + key.equals(k[i])); if (key.equalsIgnoreCase(k[i])) { v[i] = value; found = true; } if (found) break; a++; } //System.out.println(a == k.length); if (a == k.length); { k[count] = key; v[count] = value; //System.out.println(k[count] + " " + v[count]); count++; //System.out.println(count); } } public String get(String key) { String output = "a"; for(int i = 0; i < k.length; i++) { if(!key.equalsIgnoreCase(k[i])) { output = null; } else { output = v[i]; return output; } } return output; } public void clear() { for (int i = 0; i < k.length; i++) { k[i] = null; v[i] = null; } count = 0; } public void display() { for (int i = 0; i < k.length; i++) { System.out.println(k[i] + " " + v[i]); } } }

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  • Why is FLD1 loading NaN instead?

    - by Bernd Jendrissek
    I have a one-liner C function that is just return value * pow(1.+rate, -delay); - it discounts a future value to a present value. The interesting part of the disassembly is 0x080555b9 : neg %eax 0x080555bb : push %eax 0x080555bc : fildl (%esp) 0x080555bf : lea 0x4(%esp),%esp 0x080555c3 : fldl 0xfffffff0(%ebp) 0x080555c6 : fld1 0x080555c8 : faddp %st,%st(1) 0x080555ca : fxch %st(1) 0x080555cc : fstpl 0x8(%esp) 0x080555d0 : fstpl (%esp) 0x080555d3 : call 0x8051ce0 0x080555d8 : fmull 0xfffffff8(%ebp) While single-stepping through this function, gdb says (rate is 0.02, delay is 2; you can see them on the stack): (gdb) si 0x080555c6 30 return value * pow(1.+rate, -delay); (gdb) info float R7: Valid 0x4004a6c28f5c28f5c000 +41.68999999999999773 R6: Valid 0x4004e15c28f5c28f6000 +56.34000000000000341 R5: Valid 0x4004dceb851eb851e800 +55.22999999999999687 R4: Valid 0xc0008000000000000000 -2 =R3: Valid 0x3ff9a3d70a3d70a3d800 +0.02000000000000000042 R2: Valid 0x4004ff147ae147ae1800 +63.77000000000000313 R1: Valid 0x4004e17ae147ae147800 +56.36999999999999744 R0: Valid 0x4004efb851eb851eb800 +59.92999999999999972 Status Word: 0x1861 IE PE SF TOP: 3 Control Word: 0x037f IM DM ZM OM UM PM PC: Extended Precision (64-bits) RC: Round to nearest Tag Word: 0x0000 Instruction Pointer: 0x73:0x080555c3 Operand Pointer: 0x7b:0xbff41d78 Opcode: 0xdd45 And after the fld1: (gdb) si 0x080555c8 30 return value * pow(1.+rate, -delay); (gdb) info float R7: Valid 0x4004a6c28f5c28f5c000 +41.68999999999999773 R6: Valid 0x4004e15c28f5c28f6000 +56.34000000000000341 R5: Valid 0x4004dceb851eb851e800 +55.22999999999999687 R4: Valid 0xc0008000000000000000 -2 R3: Valid 0x3ff9a3d70a3d70a3d800 +0.02000000000000000042 =R2: Special 0xffffc000000000000000 Real Indefinite (QNaN) R1: Valid 0x4004e17ae147ae147800 +56.36999999999999744 R0: Valid 0x4004efb851eb851eb800 +59.92999999999999972 Status Word: 0x1261 IE PE SF C1 TOP: 2 Control Word: 0x037f IM DM ZM OM UM PM PC: Extended Precision (64-bits) RC: Round to nearest Tag Word: 0x0020 Instruction Pointer: 0x73:0x080555c6 Operand Pointer: 0x7b:0xbff41d78 Opcode: 0xd9e8 After this, everything goes to hell. Things get grossly over or undervalued, so even if there were no other bugs in my freeciv AI attempt, it would choose all the wrong strategies. Like sending the whole army to the arctic. (Sigh, if only I were getting that far.) I must be missing something obvious, or getting blinded by something, because I can't believe that fld1 should ever possibly fail. Even less that it should fail only after a handful of passes through this function. On earlier passes the FPU correctly loads 1 into ST(0). The bytes at 0x080555c6 definitely encode fld1 - checked with x/... on the running process. What gives?

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  • Java - is this an idiom or pattern, behavior classes with no state

    - by Berlin Brown
    I am trying to incorporate more functional programming idioms into my java development. One pattern that I like the most and avoids side effects is building classes that have behavior but they don't necessarily have any state. The behavior is locked into the methods but they only act on the parameters passed in. The code below is code I am trying to avoid: public class BadObject { private Map<String, String> data = new HashMap<String, String>(); public BadObject() { data.put("data", "data"); } /** * Act on the data class. But this is bad because we can't * rely on the integrity of the object's state. */ public void execute() { data.get("data").toString(); } } The code below is nothing special but I am acting on the parameters and state is contained within that class. We still may run into issues with this class but that is an issue with the method and the state of the data, we can address issues in the routine as opposed to not trusting the entire object. Is this some form of idiom? Is this similar to any pattern that you use? public class SemiStatefulOOP { /** * Private class implies that I can access the members of the <code>Data</code> class * within the <code>SemiStatefulOOP</code> class and I can also access * the getData method from some other class. * * @see Test1 * */ class Data { protected int counter = 0; public int getData() { return counter; } public String toString() { return Integer.toString(counter); } } /** * Act on the data class. */ public void execute(final Data data) { data.counter++; } /** * Act on the data class. */ public void updateStateWithCallToService(final Data data) { data.counter++; } /** * Similar to CLOS (Common Lisp Object System) make instance. */ public Data makeInstance() { return new Data(); } } // End of Class // Issues with the code above: I wanted to declare the Data class private, but then I can't really reference it outside of the class: I can't override the SemiStateful class and access the private members. Usage: final SemiStatefulOOP someObject = new SemiStatefulOOP(); final SemiStatefulOOP.Data data = someObject.makeInstance(); someObject.execute(data); someObject.updateStateWithCallToService(data);

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  • Simple RSA encryption (Java)

    - by jake blue
    This is simply for fun. This will not be used for any actual encryption. I'm only first year comp sci student and love cryptography. This took a long time to get working. At approximately N = 18, it begins breaking down. It won't encrypt messages properly after that point. I'm not sure why. Any insights? I'd also appreciate any links you could provide me to tutorials or interesting reading about Cryptography. import java.math.BigInteger; import java.security.SecureRandom; /** * Cryptography. * * Generates public and private keys used in encryption and * decryption * */ public class RSA { private final static BigInteger one = new BigInteger("1"); private final static SecureRandom random = new SecureRandom(); // prime numbers private BigInteger p; private BigInteger q; // modulus private BigInteger n; // totient private BigInteger t; // public key private BigInteger e; // private key private BigInteger d; private String cipherText; /** * Constructor for objects of class RSA */ public RSA(int N) { p = BigInteger.probablePrime(N/2, random); q = BigInteger.probablePrime(N/2, random); // initialising modulus n = p.multiply(q); // initialising t by euclid's totient function (p-1)(q-1) t = (p.subtract(one)).multiply(q.subtract(one)); // initialising public key ~ 65537 is common public key e = new BigInteger("65537"); } public int generatePrivateKey() { d = e.modInverse(t); return d.intValue(); } public String encrypt(String plainText) { String encrypted = ""; int j = 0; for(int i = 0; i < plainText.length(); i++){ char m = plainText.charAt(i); BigInteger bi1 = BigInteger.valueOf(m); BigInteger bi2 = bi1.modPow(e, n); j = bi2.intValue(); m = (char) j; encrypted += m; } cipherText = encrypted; return encrypted; } public String decrypt() { String decrypted = ""; int j = 0; for(int i = 0; i < cipherText.length(); i++){ char c = cipherText.charAt(i); BigInteger bi1 = BigInteger.valueOf(c); BigInteger bi2 = bi1.modPow(d, n); j = bi2.intValue(); c = (char) j; decrypted += c; } return decrypted; } }

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  • EF4: common interface for EF entities

    - by Feryt
    Hi. I have public interface: public interface IEntity { int ID { get; set; } string Name { get; set; } bool IsEnabled { get; set; } } ehich some EF entities implements(thanks to partial class) and extesion method: public static IEnumerable<SelectListItem> ToSelectListItems<T>(this IQueryable<T> entities, int? selectedID = null) where T : IEntity { return entities.Select(c => new { c.Name, c.ID }).ToList().Select(c => new SelectListItem { Text = c.Name, Value = c.ID.ToString(), Selected = (c.ID == selectedID) }); } Calling ToSelectListItems return exception: Unable to cast the type '<EF entity name>' to type 'IEntity'. LINQ to Entities only supports casting Entity Data Model primitive types. Why, any ideas? Thank you.

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  • NSMutableSet addObject question

    - by Jacob Relkin
    I've got a class that wraps around an NSMutableSet object, and I have an instance method that adds objects (using the addObject: method) to the NSMutableSet. This works well, but I'm smelling a performance hitch because inside the method i'm explicitly calling containsObject: before adding the object to the set. Three part question: Do I need to be calling containsObject: before I add an object to the set? If so, then what actual method should I be using, containsObject or containsObjectIdenticalTo:? If that is not so, what contains method gets invoked under the hood of addObject:? This is important to me because if I pass an object to containsObject: it would return true, but if I pass it to containsObjectIdenticalTo: it would return false.

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  • How should I handle the case in which a username is already in use?

    - by idealmachine
    I'm a JavaScript programmer and new to PHP and MySQL (want to get into server-side coding). Because I'm trying to learn PHP by building a simple online game (more specifically, correspondence chess), I'm starting by implementing a simple user accounts system. Of course, user registration comes first. What are the best practices for: How I should handle the (likely) possibility that when a user tries to register, the username he has chosen is already in use, particularly when it comes to function return values?($result === true is rather ugly, and I'm not sure whether checking the MySQL error code is the best way to do it either) How to cleanly handle varying page titles?($gPageTitle = '...'; require_once 'bgsheader.php'; is also rather ugly) Anything else I'm doing wrong? In some ways, PHP is rather different from JavaScript... Here is a (rather large) excerpt of the code I have written so far. Note that this is a work in progress and is missing security checks that I will add as my next step. function addUser( $username, $password ) { global $gDB, $gPasswordSalt; $stmt = $gDB->prepare( 'INSERT INTO user(user_name, user_password, user_registration) VALUES(?, ?, NOW())' ); $stmt || trigger_error( 'Failed to prepare statement: ' . htmlspecialchars( $gDB->error ) ); $hashedPassword = hash_hmac( 'sha256', $password, $gPasswordSalt, true ); $stmt->bind_param( 'ss', $username, $hashedPassword ); if( $stmt->execute() ) { return true; } elseif( $stmt->errno == 1062) { return 'exists'; } else { trigger_error( 'Failed to execute statement: ' . htmlspecialchars( $stmt->error ) ); } } $username = $_REQUEST['username']; $password = $_REQUEST['password']; $result = addUser( $username, $password ); if( $result === true ) { $gPageTitle = 'Registration successful'; require_once 'bgsheader.php'; echo '<p>You have successfully registered as ' . htmlspecialchars( $username ) . ' on this site.</p>'; } elseif( $result == 'exists' ) { $gPageTitle = 'Username already taken'; require_once 'bgsheader.php'; echo '<p>Someone is already using the username you have chosen. Please try using another one instead.'; } else { trigger_error('This should never happen'); } require_once 'bgsfooter.php';

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