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• Adding Functions to an Implementation of Vector

  - by Meursault

  I have this implementation of vector that I've been working on for a few days using examples from a textbook: #include <iostream> #include <string> #include <cassert> #include <algorithm> #include <cstring> // Vector.h using namespace std; template <class T> class Vector { public: typedef T * iterator; Vector(); Vector(unsigned int size); Vector(unsigned int size, const T & initial); Vector(const Vector<T> & v); // copy constructor ~Vector(); unsigned int capacity() const; // return capacity of vector (in elements) unsigned int size() const; // return the number of elements in the vector bool empty() const; iterator begin(); // return an iterator pointing to the first element iterator end(); // return an iterator pointing to one past the last element T & front(); // return a reference to the first element T & back(); // return a reference to the last element void push_back(const T & value); // add a new element void pop_back(); // remove the last element void reserve(unsigned int capacity); // adjust capacity void resize(unsigned int size); // adjust size void erase(unsigned int size); // deletes an element from the vector T & operator[](unsigned int index); // return reference to numbered element Vector<T> & operator=(const Vector<T> &); private: unsigned int my_size; unsigned int my_capacity; T * buffer; }; template<class T>// Vector<T>::Vector() { my_capacity = 0; my_size = 0; buffer = 0; } template<class T> Vector<T>::Vector(const Vector<T> & v) { my_size = v.my_size; my_capacity = v.my_capacity; buffer = new T[my_size]; for (int i = 0; i < my_size; i++) buffer[i] = v.buffer[i]; } template<class T>// Vector<T>::Vector(unsigned int size) { my_capacity = size; my_size = size; buffer = new T[size]; } template<class T>// Vector<T>::Vector(unsigned int size, const T & initial) { my_size = size; //added = size my_capacity = size; buffer = new T [size]; for (int i = 0; i < size; i++) buffer[i] = initial; } template<class T>// Vector<T> & Vector<T>::operator = (const Vector<T> & v) { delete[ ] buffer; my_size = v.my_size; my_capacity = v.my_capacity; buffer = new T [my_size]; for (int i = 0; i < my_size; i++) buffer[i] = v.buffer[i]; return *this; } template<class T>// typename Vector<T>::iterator Vector<T>::begin() { return buffer; } template<class T>// typename Vector<T>::iterator Vector<T>::end() { return buffer + size(); } template<class T>// T& Vector<T>::Vector<T>::front() { return buffer[0]; } template<class T>// T& Vector<T>::Vector<T>::back() { return buffer[size - 1]; } template<class T> void Vector<T>::push_back(const T & v) { if (my_size >= my_capacity) reserve(my_capacity +5); buffer [my_size++] = v; } template<class T>// void Vector<T>::pop_back() { my_size--; } template<class T>// void Vector<T>::reserve(unsigned int capacity) { if(buffer == 0) { my_size = 0; my_capacity = 0; } if (capacity <= my_capacity) return; T * new_buffer = new T [capacity]; assert(new_buffer); copy (buffer, buffer + my_size, new_buffer); my_capacity = capacity; delete[] buffer; buffer = new_buffer; } template<class T>// unsigned int Vector<T>::size()const { return my_size; } template<class T>// void Vector<T>::resize(unsigned int size) { reserve(size); my_size = size; } template<class T>// T& Vector<T>::operator[](unsigned int index) { return buffer[index]; } template<class T>// unsigned int Vector<T>::capacity()const { return my_capacity; } template<class T>// Vector<T>::~Vector() { delete[]buffer; } template<class T> void Vector<T>::erase(unsigned int size) { } int main() { Vector<int> v; v.reserve(2); assert(v.capacity() == 2); Vector<string> v1(2); assert(v1.capacity() == 2); assert(v1.size() == 2); assert(v1[0] == ""); assert(v1[1] == ""); v1[0] = "hi"; assert(v1[0] == "hi"); Vector<int> v2(2, 7); assert(v2[1] == 7); Vector<int> v10(v2); assert(v10[1] == 7); Vector<string> v3(2, "hello"); assert(v3.size() == 2); assert(v3.capacity() == 2); assert(v3[0] == "hello"); assert(v3[1] == "hello"); v3.resize(1); assert(v3.size() == 1); assert(v3[0] == "hello"); Vector<string> v4 = v3; assert(v4.size() == 1); assert(v4[0] == v3[0]); v3[0] = "test"; assert(v4[0] != v3[0]); assert(v4[0] == "hello"); v3.pop_back(); assert(v3.size() == 0); Vector<int> v5(7, 9); Vector<int>::iterator it = v5.begin(); while (it != v5.end()) { assert(*it == 9); ++it; } Vector<int> v6; v6.push_back(100); assert(v6.size() == 1); assert(v6[0] == 100); v6.push_back(101); assert(v6.size() == 2); assert(v6[0] == 100); v6.push_back(101); cout << "SUCCESS\n"; } So far it works pretty well, but I want to add a couple of functions to it that I can't find examples for, a SWAP function that would look at two elements of the vector and switch their values and and an ERASE function that would delete a specific value or range of values in the vector. How should I begin implementing the two extra functions?

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• How can i shorten my code for various winform calls in MDI

  - by Shantanu Gupta

  I have a mdi where i have several line of code like the given below. Only chage is Form object which is being opened. So I want to all this work using only single function defination. When I tries to capture sender it gives me ToolStipMenuItem here. But I want its sender to be form name so that I can open its corresponding form. private void purchaseInvoiceToolStripMenuItem_Click(object sender, EventArgs e) { Forms.PurchaseInvoice purinv = new DigitalInvy.Forms.PurchaseInvoice(); purinv.Show(); } private void lederGroupsToolStripMenuItem_Click(object sender, EventArgs e) { Forms.LedgerGroup lgrp = new DigitalInvy.Forms.LedgerGroup(); lgrp.Show(); } private void voucherEntryToolStripMenuItem_Click(object sender, EventArgs e) { Forms.VoucherEntry ventry = new DigitalInvy.Forms.VoucherEntry(); ventry.Show(); } private void currencyToolStripMenuItem_Click(object sender, EventArgs e) { Forms.CurrencyMaster currency = new DigitalInvy.Forms.CurrencyMaster(); currency.Show(); } private void countryToolStripMenuItem_Click(object sender, EventArgs e) { Forms.CountryMaster country = new DigitalInvy.Forms.CountryMaster(); country.Show(); }

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• Having template function defination in cpp file - Not work for VC6

  - by Yan Cheng CHEOK

  I have the following source code : // main.cpp #include "a.h" int main() { A::push(100); } // a.cpp #include "a.h" template <class T> void A::push(T t) { } template void A::push(int t); // a.h #ifndef A_H class A { public: template <class T> static void push(T t); }; #endif The code compiled charming and no problem under VC2008. But when come to my beloved VC6, it give me error : main.obj : error LNK2001: unresolved external symbol "public: static void __cdecl A::push(int)" (?push@A@@SAXH@Z) Any workaround? I just want to ensure my function definition is re-inside cpp file.

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• Mixing secure & unsecure channels

  - by user305023

  I am unable to use an unsecure channel once a secure channel has already been registered. The code below works only if on the client side, the unsecured channel is registered before. Is it possible to mix secure and unsecure channels without any constraint on the registration order ? using System; using System.Collections; using System.Runtime.Remoting; using System.Runtime.Remoting.Channels; using System.Runtime.Remoting.Channels.Tcp; public class SampleObject : MarshalByRefObject { public DateTime GetTest() { return DateTime.Now; } } public class SampleObject2 : MarshalByRefObject { public DateTime GetTest2() { return DateTime.Now; } } static class ProgramClient { private static TcpClientChannel RegisterChannel(bool secure, string name, int priority) { IDictionary properties = new Hashtable(); properties.Add("secure", secure); properties.Add("name", name); properties.Add("priority", priority); var clientChannel = new TcpClientChannel(properties, null); ChannelServices.RegisterChannel(clientChannel, false); return clientChannel; } private static void Secure() { RegisterChannel(true, "clientSecure", 2); var testSecure = (SampleObject2)Activator.GetObject(typeof(SampleObject2), "tcp://127.0.0.1:8081/Secured.rem"); Console.WriteLine("secure: " + testSecure.GetTest2().ToLongTimeString()); } private static void Unsecure() { RegisterChannel(false, "clientUnsecure", 1); var test = (SampleObject)Activator.GetObject(typeof(SampleObject), "tcp://127.0.0.1:8080/Unsecured.rem"); Console.WriteLine("unsecure: " + test.GetTest().ToLongTimeString()); } internal static void MainClient() { Console.Write("Press Enter to start."); Console.ReadLine(); // Works only in this order Unsecure(); Secure(); Console.WriteLine("Press ENTER to end"); Console.ReadLine(); } } static class ProgramServer { private static TcpServerChannel RegisterChannel(int port, bool secure, string name) { IDictionary properties = new Hashtable(); properties.Add("port", port); properties.Add("secure", secure); properties.Add("name", name); //properties.Add("impersonate", false); var serverChannel = new TcpServerChannel(properties, null); ChannelServices.RegisterChannel(serverChannel, secure); return serverChannel; } private static void StartUnsecure() { RegisterChannel(8080, false, "unsecure"); RemotingConfiguration.RegisterWellKnownServiceType(typeof(SampleObject), "Unsecured.rem", WellKnownObjectMode.Singleton); } private static void StartSecure() { RegisterChannel(8081, true, "secure"); RemotingConfiguration.RegisterWellKnownServiceType(typeof(SampleObject2), "Secured.rem", WellKnownObjectMode.Singleton); } internal static void MainServer() { StartUnsecure(); StartSecure(); Console.WriteLine("Unsecure: 8080\n Secure: 8081"); Console.WriteLine("Press the enter key to exit..."); Console.ReadLine(); } } class Program { static void Main(string[] args) { if (args.Length == 1 && args[0] == "server") ProgramServer.MainServer(); else ProgramClient.MainClient(); } }

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• Asynchronous NSURLConnection Throws EXC_BAD_ACCESS

  - by Sheehan Alam

  I'm not really sure why my code is throwing a EXC_BAD_ACCESS, I have followed the guidelines in Apple's documentation: -(void)getMessages:(NSString*)stream{ NSString* myURL = [NSString stringWithFormat:@"http://www.someurl.com"]; NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:myURL]]; NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self]; if (theConnection) { receivedData = [[NSMutableData data] retain]; } else { NSLog(@"Connection Failed!"); } } And my delegate methods #pragma mark NSURLConnection Delegate Methods - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { // This method is called when the server has determined that it // has enough information to create the NSURLResponse. // It can be called multiple times, for example in the case of a // redirect, so each time we reset the data. // receivedData is an instance variable declared elsewhere. [receivedData setLength:0]; } - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { // Append the new data to receivedData. // receivedData is an instance variable declared elsewhere. [receivedData appendData:data]; } - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { // release the connection, and the data object [connection release]; // receivedData is declared as a method instance elsewhere [receivedData release]; // inform the user NSLog(@"Connection failed! Error - %@ %@", [error localizedDescription], [[error userInfo] objectForKey:NSErrorFailingURLStringKey]); } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { // do something with the data // receivedData is declared as a method instance elsewhere NSLog(@"Succeeded! Received %d bytes of data",[receivedData length]); // release the connection, and the data object [connection release]; [receivedData release]; } I get an EXC_BAD_ACCESS on didReceiveData. Even if that method simply contains an NSLog, I get the error. Note: receivedData is an NSMutableData* in my header file

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• boost::asio buffer impossible to convert parameter from char to const mutable_buffer&

  - by Ekyo777

  visual studio tells me "error C2664: 'boost::asio::mutable_buffer::mutable_buffer(const boost::asio::mutable_buffer&)': impossible to convert parameter 1 from 'char' to 'const boost::asio::mutable_buffer&' at line 163 of consuming_buffers.hpp" I am unsure of why this happen nor how to solve it(otherwise I wouldn't ask this ^^') but I think it could be related to those functions.. even tough I tried them in another project and everything worked fine... but I can hardly find what's different so... here comes code that could be relevant, if anything useful seems to be missing I'll be glad to send it. packets are all instances of this class. class CPacketBase { protected: const unsigned short _packet_type; const size_t _size; char* _data; public: CPacketBase(unsigned short packet_type, size_t size); ~CPacketBase(); size_t get_size(); const unsigned short& get_type(); virtual char* get(); virtual void set(char*); }; this sends a given packet template <typename Handler> void async_write(CPacketBase* packet, Handler handler) { std::string outbuf; outbuf.resize(packet->get_size()); outbuf = packet->get(); boost::asio::async_write( _socket , boost::asio::buffer(outbuf, packet->get_size()) , handler); } this enable reading packets and calls a function that decodes the packet's header(unsigned short) and resize the buffer to send it to another function that reads the real data from the packet template <typename Handler> void async_read(CPacketBase* packet, Handler handler) { void (CTCPConnection::*f)( const boost::system::error_code& , CPacketBase*, boost::tuple<Handler>) = &CTCPConnection::handle_read_header<Handler>; boost::asio::async_read(_socket, _buffer_data , boost::bind( f , this , boost::asio::placeholders::error , packet , boost::make_tuple(handler))); } and this is called by async_read once a packet is received template <typename Handler> void handle_read_header(const boost::system::error_code& error, CPacketBase* packet, boost::tuple<Handler> handler) { if (error) { boost::get<0>(handler)(error); } else { // Figures packet type unsigned short packet_type = *((unsigned short*) _buffer_data.c_str()); // create new packet according to type delete packet; ... // read packet's data _buffer_data.resize(packet->get_size()-2); // minus header size void (CTCPConnection::*f)( const boost::system::error_code& , CPacketBase*, boost::tuple<Handler>) = &CTCPConnection::handle_read_data<Handler>; boost::asio::async_read(_socket, _buffer_data , boost::bind( f , this , boost::asio::placeholders::error , packet , handler)); } }

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• Move to next item or position in List view on button click

  - by praveenb

  Hi, im new to Android programing I build a listview showing station names, that grabs its data from a URL. I used ArrayAdapter to accomplish listview with data. I need to navigate through station names in listview, using previous, next buttons click. I google for this task and tried in different ways to workout bt im not able to solve. shall any one pls help me out for this issue. Thanks in advance...... I tried like this ` private ListView stationList; . . public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.playscreen); // move up event handler preButton= (ImageButton) findViewById(R.id.prevButton); preButton.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { movePre(); } }); // move down event handler nxtButton= (ImageButton) findViewById(R.id.nextButton); nxtButton.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { moveNxt(); } }); stationList.setAdapter(new StationAdapter(this, android.R.layout.simple_list_item_1, _stationList)); } else { Log.d(TAG, "No Stations"); } } private void movePre(){ stationList.setSelection(stationList.getSelectedItemPosition() + 1); } // Move selected item "down" in the ViewList. private void moveNxt(){ stationList.setSelection(stationList.getSelectedItemPosition() + 1); } private class StationAdapter extends ArrayAdapter { private Vector<Station> items; public StationAdapter(Context context, int textViewResourceId, Vector<Station> items) { super(context, textViewResourceId, items); this.items = items; } public void setSelectedPosition(int pos){ selectedPos = pos; // inform the view of this change notifyDataSetChanged(); } public int getSelectedPosition(){ return selectedPos; } @Override public View getView(int position, View convertView, ViewGroup parent) { View v = convertView; if (v == null) { LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); v = vi.inflate(R.layout.row, null); } Station st = items.get(position); if (st != null) { TextView tt = (TextView) v.findViewById(R.id.toptext); TextView bt = (TextView) v.findViewById(R.id.bottomtext); if (tt != null) { tt.setText(st.getStationName()); } if (bt != null) { bt.setText(st.getCT()); } } return v; } } `

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• Iphone App crashing on launch

  - by Declan Scott

  Hey, My simple iphone app is crashing on launch, it says "the application downloadText quit unexcpectedly i none of these windows that pop up when a mac app crashes and has a send to Apple button. My .h is below and i would greatly appreciate it if anyone could give me a hand as to what's wrong? thanks, Declan `#import "downloadTextViewController.h" @implementation downloadTextViewController // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { NSString *myPath = [self saveFilePath]; NSLog(myPath); BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:myPath]; if (fileExists) { NSArray *values = [[NSArray alloc] initWithContentsOfFile:myPath]; textView.text = [values objectAtIndex:0]; [values release]; } // notification UIApplication *myApp = [UIApplication sharedApplication]; // add yourself to the dispatch table [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillTerminate:) name:UIApplicationWillTerminateNotification object:myApp]; [super viewDidLoad]; } (IBAction)fetchData { /// Show activityIndicator / progressView NSURLRequest *downloadRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://simpsonatyapps.com/exampletext.txt"] cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:1.0]; NSURLConnection *downloadConnection = [[NSURLConnection alloc] initWithRequest:downloadRequest delegate:self]; if (downloadConnection) downloadedData = [[NSMutableData data] retain]; else { /// Error message } } (void)connection:(NSURLConnection *)downloadConnection didReceiveData:(NSData *)data { [downloadedData appendData:data]; NSString *file = [[NSString alloc] initWithData:downloadedData encoding:NSUTF8StringEncoding]; textView.text = file; /// Remove activityIndicator / progressView [[UIApplication sharedApplication] setApplicationIconBadgeNumber:1]; } (NSString *) saveFilePath { NSArray *pathArray = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); return [[pathArray objectAtIndex:0] stringByAppendingPathComponent:@"savedddata.plist"]; } (void)applicationWillTerminate:(UIApplication *)application { NSArray *values = [[NSArray alloc] initWithObjects:textView.text,nil]; [values writeToFile:[self saveFilePath] atomically:YES]; [values release]; } (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } (void)dealloc { [super dealloc]; } (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse { return nil; } @end `

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• Java JFrame EventQueue

  - by asmo

  In Java, to create and show a new JFrame, I simply do this: public static void main(String[] args) { new JFrame().setVisible(true); } However, I saw many people doing it like this: public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { new JFrame().setVisible(true); } }); } Why? Are there any advantages?

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• Preventing multiple repeat selection of synchronized Controls ?

  - by BillW

  The working code sample here synchronizes (single) selection in a TreeView, ListView, and ComboBox via the use of lambda expressions in a dictionary where the Key in the dictionary is a Control, and the Value of each Key is an Action<int. Where I am stuck is that I am getting multiple repetitions of execution of the code that sets the selection in the various controls in a way that's unexpected : it's not recursing : there's no StackOverFlow error happening; but, I would like to figure out why the current strategy for preventing multiple selection of the same controls is not working. Perhaps the real problem here is distinguishing between a selection update triggered by the end-user and a selection update triggered by the code that synchronizes the other controls ? Note: I've been experimenting with using Delegates, and forms of Delegates like Action<T>, to insert executable code in Dictionaries : I "learn best" by posing programming "challenges" to myself, and implementing them, as well as studying, at the same time, the "golden words" of luminaries like Skeet, McDonald, Liberty, Troelsen, Sells, Richter. Note: Appended to this question/code, for "deep background," is a statement of how I used to do things in pre C#3.0 days where it seemed like I did need to use explicit measures to prevent recursion when synchronizing selection. Code : Assume a WinForms standard TreeView, ListView, ComboBox, all with the same identical set of entries (i.e., the TreeView has only root nodes; the ListView, in Details View, has one Column). private Dictionary<Control, Action<int>> ControlToAction = new Dictionary<Control, Action<int>>(); private void Form1_Load(object sender, EventArgs e) { // add the Controls to be synchronized to the Dictionary // with appropriate Action<int> lambda expressions ControlToAction.Add(treeView1, (i => { treeView1.SelectedNode = treeView1.Nodes[i]; })); ControlToAction.Add(listView1, (i => { listView1.Items[i].Selected = true; })); ControlToAction.Add(comboBox1, (i => { comboBox1.SelectedIndex = i; })); } private void synchronizeSelection(int i, Control currentControl) { foreach(Control theControl in ControlToAction.Keys) { // skip the 'current control' if (theControl == currentControl) continue; // for debugging only Console.WriteLine(theControl.Name + " synchronized"); // execute the Action<int> associated with the Control ControlToAction[theControl](i); } } private void treeView1_AfterSelect(object sender, TreeViewEventArgs e) { synchronizeSelection(e.Node.Index, treeView1); } private void listView1_SelectedIndexChanged(object sender, EventArgs e) { // weed out ListView SelectedIndexChanged firing // with SelectedIndices having a Count of #0 if (listView1.SelectedIndices.Count > 0) { synchronizeSelection(listView1.SelectedIndices[0], listView1); } } private void comboBox1_SelectedValueChanged(object sender, EventArgs e) { if (comboBox1.SelectedIndex > -1) { synchronizeSelection(comboBox1.SelectedIndex, comboBox1); } } background : pre C# 3.0 Seems like, back in pre C# 3.0 days, I was always using a boolean flag to prevent recursion when multiple controls were updated. For example, I'd typically have code like this for synchronizing a TreeView and ListView : assuming each Item in the ListView was synchronized with a root-level node of the TreeView via a common index : // assume ListView is in 'Details View,' has a single column, // MultiSelect = false // FullRowSelect = true // HideSelection = false; // assume TreeView // HideSelection = false // FullRowSelect = true // form scoped variable private bool dontRecurse = false; private void treeView1_AfterSelect(object sender, TreeViewEventArgs e) { if(dontRecurse) return; dontRecurse = true; listView1.Items[e.Node.Index].Selected = true; dontRecurse = false; } private void listView1_SelectedIndexChanged(object sender, EventArgs e) { if(dontRecurse) return // weed out ListView SelectedIndexChanged firing // with SelectedIndices having a Count of #0 if (listView1.SelectedIndices.Count > 0) { dontRecurse = true; treeView1.SelectedNode = treeView1.Nodes[listView1.SelectedIndices[0]]; dontRecurse = false; } } Then it seems, somewhere around FrameWork 3~3.5, I could get rid of the code to suppress recursion, and there was was no recursion (at least not when synchronizing a TreeView and a ListView). By that time it had become a "habit" to use a boolean flag to prevent recursion, and that may have had to do with using a certain third party control.

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• c# (wcf) architecture file and directory structure (and instantiation)

  - by stevenrosscampbell

  Hello and thanks for any assistance. I have a wcf service that I'm trying to properly modularize. I'm interested in finding out if there is a better way or implementing the file and directory structure along with instanciatation, is there a more appropriate way of abstraction that I may be missing? Is this the best approach? especially if performance and the ability to handle thousands of simultanious request? Currently I have this following structure: -Root\Service.cs public class Service : IService { public void CreateCustomer(Customer customer) { CustomerService customerService = new CustomerService(); customerService.Create(customer); } public void UpdateCustomer(Customer customer) { CustomerService customerService = new CustomerService(); customerService.Update(customer); } } -Root\Customer\CustomerService.cs pulbic class CustomerService { public void Create(Customer customer) { //DO SOMETHING } public void Update(Customer customer) { //DO SOMETHING } public void Delete(int customerId) { //DO SOMETHING } public Customer Retrieve(int customerId) { //DO SOMETHING } } Note: I do not include the Customer Object or the DataAccess libraries in this example as I am only concerned about the service. If you could either let me know what you think, if you know a better way, or a resource that could help out. Thanks Kindly. Steven

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• WPF Lookless Control Events

  - by Scott

  I have the following class: public class LooklessControl : Control { public List<int> IntList { get; private set; } public int CurrentInt { get; private set; } private int _index = 0; static LooklessControl() { DefaultStyleKeyProperty.OverrideMetadata(typeof(LooklessControl), new FrameworkPropertyMetadata(typeof(LooklessControl))); } public LooklessControl() { IntList = new List<int>(); for (int i = 0; i < 10; i++) { IntList.Add(i); } CurrentInt = IntList[_index]; } public static readonly RoutedCommand NextItemCommand = new RoutedCommand("NextItemCommand", typeof(LooklessControl)); private void ExecutedNextItemCommand(object sender, ExecutedRoutedEventArgs e) { NextItemHandler(); } private void CanExecuteNextItemCommand(object sender, CanExecuteRoutedEventArgs e) { e.CanExecute = true; } public static readonly RoutedCommand PrevItemCommand = new RoutedCommand("PrevItemCommand", typeof(LooklessControl)); private void ExecutedPrevItemCommand(ExecutedRoutedEventArgs e) { PrevItemHandler(); } private void CanExecutePrevItemCommand(object sender, CanExecuteRoutedEventArgs e) { e.CanExecute = true; } public static readonly RoutedEvent NextItemEvent = EventManager.RegisterRoutedEvent("NextItemEvent", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(LooklessControl)); public event RoutedEventHandler NextItem { add { AddHandler(NextItemEvent, value); } remove { RemoveHandler(NextItemEvent, value); } } private void RaiseNextItemEvent() { RoutedEventArgs args = new RoutedEventArgs(LooklessControl.NextItemEvent); RaiseEvent(args); } public static readonly RoutedEvent PrevItemEvent = EventManager.RegisterRoutedEvent("PrevItemEvent", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(LooklessControl)); public event RoutedEventHandler PrevItem { add { AddHandler(PrevItemEvent, value); } remove { RemoveHandler(PrevItemEvent, value); } } private void RaisePrevItemEvent() { RoutedEventArgs args = new RoutedEventArgs(LooklessControl.PrevItemEvent); RaiseEvent(args); } private void NextItemHandler() { _index++; if (_index == IntList.Count) { _index = 0; } CurrentInt = IntList[_index]; RaiseNextItemEvent(); } private void PrevItemHandler() { _index--; if (_index == 0) { _index = IntList.Count - 1; } CurrentInt = IntList[_index]; RaisePrevItemEvent(); } } The class has a default style, in Generic.xaml, that looks like this: <Style x:Key="{x:Type local:LooklessControl}" TargetType="{x:Type local:LooklessControl}"> <Setter Property="Height" Value="200"/> <Setter Property="Width" Value="90"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type local:LooklessControl}"> <Border BorderBrush="Black" BorderThickness="1" Padding="2"> <Grid> <Grid.RowDefinitions> <RowDefinition Height="20"/> <RowDefinition Height="*"/> </Grid.RowDefinitions> <Rectangle Grid.Row="0" Fill="LightGray"/> <Rectangle Grid.Row="1" Fill="Gainsboro"/> <Grid Grid.Row="0"> <Grid.ColumnDefinitions> <ColumnDefinition Width="10"/> <ColumnDefinition Width="*"/> <ColumnDefinition Width="10"/> </Grid.ColumnDefinitions> <Path Grid.Column="0" x:Name="pathLeftArrow" Data="M0,0.5 L1,1 1,0Z" Width="6" Height="14" Stretch="Fill" HorizontalAlignment="Center" Fill="SlateBlue"/> <TextBlock Grid.Column="1" Name="textBlock" Text="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=CurrentInt}" HorizontalAlignment="Center" VerticalAlignment="Center" FontFamily="Junction" FontSize="13"/> <Path Grid.Column="2" x:Name="pathRightArrow" Data="M0,0 L1,0.5 0,1Z" Width="6" Height="14" Stretch="Fill" HorizontalAlignment="Center" Fill="SlateBlue"/> </Grid> <ListBox Grid.Row="1" HorizontalContentAlignment="Center" VerticalContentAlignment="Center" Background="Transparent" ItemsSource="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=IntList}"/> </Grid> </Border> </ControlTemplate> </Setter.Value> </Setter> </Style> How do I make it so that when the user clicks on pathLeftArrow it fires LooklessControl.PrevItemCommand, or or they click on pathRightArrow and it fires LooklessControl.NextItemCommand, or they click on an item in the ListBox and LooklessControl is notified of the newly selected item? In other words, without adding x:Class to the top of Generic.xaml and thus creating a code-behind file for it, which I assume you wouldn't want to do, how do you handle events for elements in your xaml that don't have a Command property (which is just about everything other than a Button)? Should LooklessControl have it's own XAML file (much like what you get when you create a new UserControl) associated with it that Generic.xaml just pulls in as a MergedDictionar as its default template? Or is there some other acknowledged way to do what I'm trying to do?

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• boost::binding that which is already bound

  - by PaulH

  I have a Visual Studio 2008 C++ application that does something like this: template< typename Fcn > inline void Bar( Fcn fcn ) // line 84 { fcn(); }; template< typename Fcn > inline void Foo( Fcn fcn ) { // this works fine Bar( fcn ); // this fails to compile boost::bind( Bar, fcn )(); }; void main() { SYSTEM_POWER_STATUS_EX status = { 0 }; Foo( boost::bind( ::GetSystemPowerStatusEx, &status, true ) ); // line 160 } *The call to GetSystemPowerStatusEx() is just for demonstration. Insert your favorite call there and the behavior is the same. When I go to compile this, I get 84 errors. I won't post them all unless asked, but they start with this: 1>.\MyApp.cpp(99) : error C2896: 'boost::_bi::bind_t<_bi::dm_result<MT::* ,A1>::type,boost::_mfi::dm<M,T>,_bi::list_av_1<A1>::type> boost::bind(M T::* ,A1)' : cannot use function template 'void Bar(Fcn)' as a function argument 1> .\MyApp.cpp(84) : see declaration of 'Bar' 1> .\MyApp.cpp(160) : see reference to function template instantiation 'void Foo<boost::_bi::bind_t<R,F,L>>(Fcn)' being compiled 1> with 1> [ 1> R=BOOL, 1> F=BOOL (__cdecl *)(PSYSTEM_POWER_STATUS_EX,BOOL), 1> L=boost::_bi::list2<boost::_bi::value<_SYSTEM_POWER_STATUS_EX *>,boost::_bi::value<bool>>, 1> Fcn=boost::_bi::bind_t<BOOL,BOOL (__cdecl *)(PSYSTEM_POWER_STATUS_EX,BOOL),boost::_bi::list2<boost::_bi::value<_SYSTEM_POWER_STATUS_EX *>,boost::_bi::value<bool>>> 1> ] If anybody can point out what I may be doing wrong, I would appreciate it. Thanks, PaulH

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• populate UITableView from json

  - by mcgrailm

  Hello all working on my building my first iDevice app and I am trying to populate a UITableView with data from json result I can get it to load from plist array no propblem and I can even see my json the problem I'm having is that the UITableView never gets to see the json results please bare with me as this is first time with obj-c or anything like it in my .h file @interface TableViewViewController : UIViewController <UITableViewDataSource, UITableViewDelegate> { NSArray *exercises; NSMutableData *responseData; } in my .m file - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return exercises.count; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { //create a cell UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"]; // fill it with contnets cell.textLabel.text = [exercises objectAtIndex:indexPath.row]; // return it return cell; } // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { responseData = [[NSMutableData data] retain]; NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://url_to_json"]]; [[NSURLConnection alloc] initWithRequest:request delegate:self ]; // load from plist //NSString *myfile = [[NSBundle mainBundle] pathForResource:@"exercise" ofType:@"plist"]; //exercises = [[NSArray alloc] initWithContentsOfFile:myfile]; [super viewDidLoad]; } - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { [responseData setLength:0]; } - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { [responseData appendData:data]; } - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { NSLog(@"Connection failed: %@", [error description]); } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { [connection release]; NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding]; [responseData release]; NSDictionary *dictionary = [responseString JSONValue]; NSArray *response = [dictionary objectForKey:@"response"]; exercises = [[NSArray alloc] initWithArray:response]; }

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• Qt 4.6 Adding objects and sub-objects to QWebView window object (C++ & Javascript)

  - by Cor

  I am working with Qt's QWebView, and have been finding lots of great uses for adding to the webkit window object. One thing I would like to do is nested objects... for instance: in Javascript I can... var api = new Object; api.os = new Object; api.os.foo = function(){} api.window = new Object(); api.window.bar = function(){} obviously in most cases this would be done through a more OO js-framework. This results in a tidy structure of: >>>api ------------------------------------------------------- - api Object {os=Object, more... } - os Object {} foo function() - win Object {} bar function() ------------------------------------------------------- Right now I'm able to extend the window object with all of the qtC++ methods and signals I need, but they all have 'seem' to have to be in a root child of "window". This is forcing me to write a js wrapper object to get the hierarchy that I want in the DOM. >>>api ------------------------------------------------------- - api Object {os=function, more... } - os_foo function() - win_bar function() ------------------------------------------------------- This is a pretty simplified example... I want objects for parameters, etc... Does anyone know of a way to pass an child object with the object that extends the WebFrame's window object? Here's some example code of how I'm adding the object: mainwindow.h #ifndef MAINWINDOW_H #define MAINWINDOW_H #include <QtGui/QMainWindow> #include <QWebFrame> #include "mainwindow.h" #include "happyapi.h" class QWebView; class QWebFrame; QT_BEGIN_NAMESPACE class MainWindow : public QMainWindow { Q_OBJECT public: MainWindow(QWidget *parent = 0); private slots: void attachWindowObject(); void bluesBros(); private: QWebView *view; HappyApi *api; QWebFrame *frame; }; #endif // MAINWINDOW_H mainwindow.cpp #include <QDebug> #include <QtGui> #include <QWebView> #include <QWebPage> #include "mainwindow.h" #include "happyapi.h" MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) { view = new QWebView(this); view->load(QUrl("file:///Q:/example.htm")); api = new HappyApi(this); QWebPage *page = view->page(); frame = page->mainFrame(); attachWindowObject(); connect(frame, SIGNAL(javaScriptWindowObjectCleared()), this, SLOT(attachWindowObject())); connect(api, SIGNAL(win_bar()), this, SLOT(bluesBros())); setCentralWidget(view); }; void MainWindow::attachWindowObject() { frame->addToJavaScriptWindowObject(QString("api"), api); }; void MainWindow::bluesBros() { qDebug() << "foo and bar are getting the band back together!"; }; happyapi.h #ifndef HAPPYAPI_H #define HAPPYAPI_H #include <QObject> class HappyApi : public QObject { Q_OBJECT public: HappyApi(QObject *parent); public slots: void os_foo(); signals: void win_bar(); }; #endif // HAPPYAPI_H happyapi.cpp #include <QDebug> #include "happyapi.h" HappyApi::HappyApi(QObject *parent) : QObject(parent) { }; void HappyApi::os_foo() { qDebug() << "foo called, it want's it's bar back"; }; I'm reasonably new to C++ programming (coming from a web and python background). Hopefully this example will serve to not only help other new users, but be something interesting for a more experienced c++ programmer to elaborate on. Thanks for any assistance that can be provided. :)

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• The Bizarre Hidden Powers of the Preprocessor? [closed]

  - by ApprenticeHacker

  The preprocessor in C and C++ deserves an entire essay on its own to explore its rich possibilities for obfuscation. It is true that the C++ (and C) preprocessor can be used for a lot of powerful stuff. #ifdefs and #defines are often used to determine platforms, compilers and backends. Manipulating the code likewise. However, can anyone list some of the most powerful and bizarre things you can do with the preprocessor? The most sinister use of the preprocessor I've found is this: #ifndef DONE #ifdef TWICE // put stuff here to declare 3rd time around void g(char* str); #define DONE #else // TWICE #ifdef ONCE // put stuff here to declare 2nd time around void g(void* str); #define TWICE #else // ONCE // put stuff here to declare 1st time around void g(std::string str); #define ONCE #endif // ONCE #endif // TWICE #endif // DONE This declares different things based on how many times the header is included. Are there any other bizarre unknown powers of the C++ preprocessor?

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• Boost.Python wrapping hierarchies avoiding diamond inheritance

  - by stbuton

  I'm having some trouble seeing what the best way to wrap a series of classes with Boost.Python while avoiding messy inheritance problems. Say I have the classes A, B, and C with the following structure: struct A { virtual void foo(); virtual void bar(); virtual void baz(); }; struct B : public A { virtual void quux(); }; struct C : public A { virtual void foobar(); }; I want to wrap all classes A, B, and C such that they are extendable from Python. The normal method for accomplishing this would be along the lines of: struct A_Wrapper : public A, boost::python::wrapper<A> { //dispatch logic for virtual functions }; Now for classes B and C which extend from A I would like to be able to inherit and share the wrapping implementation for A. So I'd like to be able to do something along the lines of: struct B_Wrapper : public B, public A_Wrapper, public boost::python::wrapper<B> { //dispatch logic specific for B }; struct C_Wrapper : public C, public A_Wrapper, public boost::python::wrapper<C> { //dispatch logic specific for C } However, it seems like that would introduce all manner of nastiness with the double inheritance of the boost wrapper base and the double inheritance of A in the B_Wrapper and C_Wrapper objects. Is there a common way that this instance is solved that I'm missing? thanks.

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• NSURLConnection not "firing" until UITableView scrolls..

  - by Simon

  Hi, I've got a UITableView that loads an image asynchronously and places it in the UITableViewCell once it's loaded (I'm using almost the exact same code as in the "LazyTableImages" tutorial). This works fine for all images when I scroll the table, but it's not loading the images that are first in the view. The code is definitely working fine as the class that actually sends the NSURLConnection request is being called correctly (I added an NSLog and it reached the console). The NSURLConnection is just not calling the delegate methods (didReceiveData, connectionDidFinishLoading, etc). Here's my code: HomeController.m - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; NSArray *feed = [feeds objectAtIndex: indexPath.row]; /** * Name of person */ [...] /** * Feed entry */ [...] /** * Misc work */ [...] } FeedRecord *feedRecord = [self.entries objectAtIndex:indexPath.row]; if( !feedRecord.image ) { if (self.table.dragging == NO && self.table.decelerating == NO) { [self startIconDownload:feedRecord forIndexPath:indexPath]; } cell.imageView.image = [UIImage imageNamed:@"Placeholder.png"]; } return cell; } - (void)startIconDownload:(FeedRecord *)feedRecord forIndexPath:(NSIndexPath *)indexPath { IconDownloader *iconDownloader = [imageDownloadsInProgress objectForKey:indexPath]; if (iconDownloader == nil) { iconDownloader = [[IconDownloader alloc] init]; iconDownloader.feedRecord = feedRecord; iconDownloader.indexPathInTableView = indexPath; iconDownloader.delegate = self; [imageDownloadsInProgress setObject:iconDownloader forKey:indexPath]; [iconDownloader startDownload]; [iconDownloader release]; } } IconDownload.m #import "IconDownloader.h" #import "FeedRecord.h" #define kAppIconHeight 48 @implementation IconDownloader @synthesize feedRecord; @synthesize indexPathInTableView; @synthesize delegate; @synthesize activeDownload; @synthesize imageConnection; #pragma mark - (void)dealloc { [feedRecord release]; [indexPathInTableView release]; [activeDownload release]; [imageConnection cancel]; [imageConnection release]; [super dealloc]; } - (void)startDownload { NSLog(@"%@ %@",@"Started downloading", feedRecord.profilePicture); // this shows in log self.activeDownload = [NSMutableData data]; // alloc+init and start an NSURLConnection; release on completion/failure NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest: [NSURLRequest requestWithURL: [NSURL URLWithString:feedRecord.profilePicture]] delegate:self]; self.imageConnection = conn; NSLog(@"%@",conn); // this shows in log [conn release]; } - (void)cancelDownload { [self.imageConnection cancel]; self.imageConnection = nil; self.activeDownload = nil; } #pragma mark - #pragma mark Download support (NSURLConnectionDelegate) - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { NSLog(@"%@ %@",@"Got data for", feedRecord.profilePicture); [self.activeDownload appendData:data]; } - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { NSLog(@"%@",@"Fail!"); // Clear the activeDownload property to allow later attempts self.activeDownload = nil; // Release the connection now that it's finished self.imageConnection = nil; } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { NSLog(@"%@ %@",@"Done", feedRecord.profilePicture); // Set appIcon and clear temporary data/image UIImage *image = [[UIImage alloc] initWithData:self.activeDownload]; self.feedRecord.image = image; self.activeDownload = nil; [image release]; // Release the connection now that it's finished self.imageConnection = nil; NSLog(@"%@ %@",@"Our delegate is",delegate); // call our delegate and tell it that our icon is ready for display [delegate feedImageDidLoad:self.indexPathInTableView]; } @end Has anyone else experienced anything like this or can identify an issue with my code? Thanks!

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• 11415 compile errors FTW?!

  - by Koning Baard

  Hello. This is something I've really never seen but, I downloaded the source code of the sine wave example at http://www.audiosynth.com/sinewavedemo.html . It is in an old Project Builder Project format, and I want to compile it with Xcode (GCC). However, Xcode gives me 11415 compile errors. The first few are (all in the precompilation of AppKit.h): /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:31:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:31: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:33:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:33: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:35:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:35: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:36:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:36: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:37:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:37: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:38:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:38: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:40:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:40: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:42:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:42: error: expected identifier or '(' before '@' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:48:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:48: error: expected identifier or '(' before '@' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:54:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:54: error: expected identifier or '(' before '@' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:59:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:59: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:61:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:61: error: expected identifier or '(' before '@' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:69:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:69: error: expected identifier or '(' before '+' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:71:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:71: error: expected identifier or '(' before '+' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:39:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:39: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:40:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:40: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:41:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:41: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:42:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:42: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:43:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:43: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:44:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:44: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:45:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:45: error: expected identifier or '(' before '-' token /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:46:0 /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSValue.h:46: error: expected identifier or '(' before '-' token Some of the code is: HAL.c /* * HAL.c * Sinewave * * Created by james on Fri Apr 27 2001. * Copyright (c) 2001 __CompanyName__. All rights reserved. * */ #include "HAL.h" #include "math.h" appGlobals gAppGlobals; OSStatus appIOProc (AudioDeviceID inDevice, const AudioTimeStamp* inNow, const AudioBufferList* inInputData, const AudioTimeStamp* inInputTime, AudioBufferList* outOutputData, const AudioTimeStamp* inOutputTime, void* device); #define FailIf(cond, handler) \ if (cond) { \ goto handler; \ } #define FailWithAction(cond, action, handler) \ if (cond) { \ { action; } \ goto handler; \ } // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // HAL Sample Code ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ //#define noErr 0 //#define false 0 OSStatus SetupHAL (appGlobalsPtr globals) { OSStatus err = noErr; UInt32 count, bufferSize; AudioDeviceID device = kAudioDeviceUnknown; AudioStreamBasicDescription format; // get the default output device for the HAL count = sizeof(globals->device); // it is required to pass the size of the data to be returned err = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice, &count, (void *) &device); fprintf(stderr, "kAudioHardwarePropertyDefaultOutputDevice %d\n", err); if (err != noErr) goto Bail; // get the buffersize that the default device uses for IO count = sizeof(globals->deviceBufferSize); // it is required to pass the size of the data to be returned err = AudioDeviceGetProperty(device, 0, false, kAudioDevicePropertyBufferSize, &count, &bufferSize); fprintf(stderr, "kAudioDevicePropertyBufferSize %d %d\n", err, bufferSize); if (err != noErr) goto Bail; // get a description of the data format used by the default device count = sizeof(globals->deviceFormat); // it is required to pass the size of the data to be returned err = AudioDeviceGetProperty(device, 0, false, kAudioDevicePropertyStreamFormat, &count, &format); fprintf(stderr, "kAudioDevicePropertyStreamFormat %d\n", err); fprintf(stderr, "sampleRate %g\n", format.mSampleRate); fprintf(stderr, "mFormatFlags %08X\n", format.mFormatFlags); fprintf(stderr, "mBytesPerPacket %d\n", format.mBytesPerPacket); fprintf(stderr, "mFramesPerPacket %d\n", format.mFramesPerPacket); fprintf(stderr, "mChannelsPerFrame %d\n", format.mChannelsPerFrame); fprintf(stderr, "mBytesPerFrame %d\n", format.mBytesPerFrame); fprintf(stderr, "mBitsPerChannel %d\n", format.mBitsPerChannel); if (err != kAudioHardwareNoError) goto Bail; FailWithAction(format.mFormatID != kAudioFormatLinearPCM, err = paramErr, Bail); // bail if the format is not linear pcm // everything is ok so fill in these globals globals->device = device; globals->deviceBufferSize = bufferSize; globals->deviceFormat = format; Bail: return (err); } /* struct AudioStreamBasicDescription { Float64 mSampleRate; // the native sample rate of the audio stream UInt32 mFormatID; // the specific encoding type of audio stream UInt32 mFormatFlags; // flags specific to each format UInt32 mBytesPerPacket; // the number of bytes in a packet UInt32 mFramesPerPacket; // the number of frames in each packet UInt32 mBytesPerFrame; // the number of bytes in a frame UInt32 mChannelsPerFrame; // the number of channels in each frame UInt32 mBitsPerChannel; // the number of bits in each channel }; typedef struct AudioStreamBasicDescription AudioStreamBasicDescription; */ // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // This is a simple playThru ioProc. It simply places the data in the input buffer back into the output buffer. // Watch out for feedback from Speakers to Microphone OSStatus appIOProc (AudioDeviceID inDevice, const AudioTimeStamp* inNow, const AudioBufferList* inInputData, const AudioTimeStamp* inInputTime, AudioBufferList* outOutputData, const AudioTimeStamp* inOutputTime, void* appGlobals) { appGlobalsPtr globals = appGlobals; int i; double phase = gAppGlobals.phase; double amp = gAppGlobals.amp; double pan = gAppGlobals.pan; double freq = gAppGlobals.freq * 2. * 3.14159265359 / globals->deviceFormat.mSampleRate; int numSamples = globals->deviceBufferSize / globals->deviceFormat.mBytesPerFrame; // assume floats for now.... float *out = outOutputData->mBuffers[0].mData; for (i=0; i<numSamples; ++i) { float wave = sin(phase) * amp; phase = phase + freq; *out++ = wave * (1.0-pan); *out++ = wave * pan; } gAppGlobals.phase = phase; return (kAudioHardwareNoError); } // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ OSStatus StartPlayingThruHAL(appGlobalsPtr globals) { OSStatus err = kAudioHardwareNoError; if (globals->soundPlaying) return 0; globals->phase = 0.0; err = AudioDeviceAddIOProc(globals->device, appIOProc, (void *) globals); // setup our device with an IO proc if (err != kAudioHardwareNoError) goto Bail; err = AudioDeviceStart(globals->device, appIOProc); // start playing sound through the device if (err != kAudioHardwareNoError) goto Bail; globals->soundPlaying = true; // set the playing status global to true Bail: return (err); } // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ OSStatus StopPlayingThruHAL(appGlobalsPtr globals) { OSStatus err = kAudioHardwareNoError; if (!globals->soundPlaying) return 0; err = AudioDeviceStop(globals->device, appIOProc); // stop playing sound through the device if (err != kAudioHardwareNoError) goto Bail; err = AudioDeviceRemoveIOProc(globals->device, appIOProc); // remove the IO proc from the device if (err != kAudioHardwareNoError) goto Bail; globals->soundPlaying = false; // set the playing status global to false Bail: return (err); } Sinewave.m // // a very simple Cocoa CoreAudio app // by James McCartney [email protected] www.audiosynth.com // // Sinewave - this class implements a sine oscillator with dezippered control of frequency, pan and amplitude // #import "Sinewave.h" // define a C struct from the Obj-C object so audio callback can access data typedef struct { @defs(Sinewave); } sinewavedef; // this is the audio processing callback. OSStatus appIOProc (AudioDeviceID inDevice, const AudioTimeStamp* inNow, const AudioBufferList* inInputData, const AudioTimeStamp* inInputTime, AudioBufferList* outOutputData, const AudioTimeStamp* inOutputTime, void* defptr) { sinewavedef* def = defptr; // get access to Sinewave's data int i; // load instance vars into registers double phase = def->phase; double amp = def->amp; double pan = def->pan; double freq = def->freq; double ampz = def->ampz; double panz = def->panz; double freqz = def->freqz; int numSamples = def->deviceBufferSize / def->deviceFormat.mBytesPerFrame; // assume floats for now.... float *out = outOutputData->mBuffers[0].mData; for (i=0; i<numSamples; ++i) { float wave = sin(phase) * ampz; // generate sine wave phase = phase + freqz; // increment phase // write output *out++ = wave * (1.0-panz); // left channel *out++ = wave * panz; // right channel // de-zipper controls panz = 0.001 * pan + 0.999 * panz; ampz = 0.001 * amp + 0.999 * ampz; freqz = 0.001 * freq + 0.999 * freqz; } // save registers back to object def->phase = phase; def->freqz = freqz; def->ampz = ampz; def->panz = panz; return kAudioHardwareNoError; } @implementation Sinewave - (void) setup { OSStatus err = kAudioHardwareNoError; UInt32 count; device = kAudioDeviceUnknown; initialized = NO; // get the default output device for the HAL count = sizeof(device); // it is required to pass the size of the data to be returned err = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice, &count, (void *) &device); if (err != kAudioHardwareNoError) { fprintf(stderr, "get kAudioHardwarePropertyDefaultOutputDevice error %ld\n", err); return; } // get the buffersize that the default device uses for IO count = sizeof(deviceBufferSize); // it is required to pass the size of the data to be returned err = AudioDeviceGetProperty(device, 0, false, kAudioDevicePropertyBufferSize, &count, &deviceBufferSize); if (err != kAudioHardwareNoError) { fprintf(stderr, "get kAudioDevicePropertyBufferSize error %ld\n", err); return; } fprintf(stderr, "deviceBufferSize = %ld\n", deviceBufferSize); // get a description of the data format used by the default device count = sizeof(deviceFormat); // it is required to pass the size of the data to be returned err = AudioDeviceGetProperty(device, 0, false, kAudioDevicePropertyStreamFormat, &count, &deviceFormat); if (err != kAudioHardwareNoError) { fprintf(stderr, "get kAudioDevicePropertyStreamFormat error %ld\n", err); return; } if (deviceFormat.mFormatID != kAudioFormatLinearPCM) { fprintf(stderr, "mFormatID != kAudioFormatLinearPCM\n"); return; } if (!(deviceFormat.mFormatFlags & kLinearPCMFormatFlagIsFloat)) { fprintf(stderr, "Sorry, currently only works with float format....\n"); return; } initialized = YES; fprintf(stderr, "mSampleRate = %g\n", deviceFormat.mSampleRate); fprintf(stderr, "mFormatFlags = %08lX\n", deviceFormat.mFormatFlags); fprintf(stderr, "mBytesPerPacket = %ld\n", deviceFormat.mBytesPerPacket); fprintf(stderr, "mFramesPerPacket = %ld\n", deviceFormat.mFramesPerPacket); fprintf(stderr, "mChannelsPerFrame = %ld\n", deviceFormat.mChannelsPerFrame); fprintf(stderr, "mBytesPerFrame = %ld\n", deviceFormat.mBytesPerFrame); fprintf(stderr, "mBitsPerChannel = %ld\n", deviceFormat.mBitsPerChannel); } - (void)setAmpVal:(double)val { amp = val; } - (void)setFreqVal:(double)val { freq = val * 2. * 3.14159265359 / deviceFormat.mSampleRate; } - (void)setPanVal:(double)val { pan = val; } - (BOOL)start { OSStatus err = kAudioHardwareNoError; sinewavedef *def; if (!initialized) return false; if (soundPlaying) return false; // initialize phase and de-zipper filters. phase = 0.0; freqz = freq; ampz = amp; panz = pan; def = (sinewavedef *)self; err = AudioDeviceAddIOProc(device, appIOProc, (void *) def); // setup our device with an IO proc if (err != kAudioHardwareNoError) return false; err = AudioDeviceStart(device, appIOProc); // start playing sound through the device if (err != kAudioHardwareNoError) return false; soundPlaying = true; // set the playing status global to true return true; } - (BOOL)stop { OSStatus err = kAudioHardwareNoError; if (!initialized) return false; if (!soundPlaying) return false; err = AudioDeviceStop(device, appIOProc); // stop playing sound through the device if (err != kAudioHardwareNoError) return false; err = AudioDeviceRemoveIOProc(device, appIOProc); // remove the IO proc from the device if (err != kAudioHardwareNoError) return false; soundPlaying = false; // set the playing status global to false return true; } @end Can anyone help me compiling this example? I'd really appriciate it. Thanks

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• Why is there ambiguity in this diamond pattern?

  - by cambr

  #include <iostream> using namespace std; class A { public: void eat(){ cout<<"A";} }; class B: public A { public: void eat(){ cout<<"B";} }; class C: public A { public: void eat(){ cout<<"C";} }; class D: public B,C { public: void eat(){ cout<<"D";} }; int main(){ A *a = new D(); a->eat(); } I am not sure this is called diamond problem or not, but why doesn't this work? When I said, a->eat() (remember eat() is not virtual), there is only one possible eat() to call, that of A. Why then, do I get this error: 'A' is an ambiguous base of 'D'

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• Why / When / How is this Android serviceBinder resetting to null?

  - by GaZ

  I've written a ListActivity for Android 2.1 which is used to display a list of event categories. As the user selects a category, the program calls a web service to retrieve a list of sub-events. For example, a top level event might be "soccer" and when the user selects this the web service would return various soccer associations (e.g. "english", "french", "german", etc.) and display them in a new list. The following code seems to work occasionally, however sometimes the call to the service (in EventsListTask) fails because the serviceBinder is null. How/Why does this happen? public class EventListsActivity extends ListActivity { private static final String EVENT_ID = "EventId"; private List<ListItem> eventList; private ArrayAdapter<ListItem> listItemArrayAdapter; private static final int LOADING_DIALOG = 1; private EventsListTask eventsListTask = null; private BFService serviceBinder; private ServiceConnection mConnection = new ServiceConnection() { public void onServiceConnected(ComponentName componentName, IBinder iBinder) { Log.i("EventListsActivity", "service connected"); serviceBinder = ((BFService.BFBinder)iBinder).getService(); } public void onServiceDisconnected(ComponentName componentName) { Log.i("EventListsActivity", "service disconnected"); serviceBinder = null; } }; @Override public void onCreate(Bundle savedInstanceState) { Log.i("EventListsActivity", "onCreate"); super.onCreate(savedInstanceState); setContentView(R.layout.list); eventList = new ArrayList<ListItem>(); listItemArrayAdapter = new ArrayAdapter<ListItem>(this, R.layout.row, eventList); setListAdapter(listItemArrayAdapter); Intent bindIntent = new Intent(this, BFService.class); bindService(bindIntent, mConnection, Context.BIND_AUTO_CREATE); int eventId = getIntent().getIntExtra(EVENT_ID, -1); if (eventsListTask == null || eventsListTask.getStatus() == AsyncTask.Status.FINISHED) { eventsListTask = new EventsListTask(); eventsListTask.execute(eventId); } } @Override protected void onDestroy() { Log.i("EventListsActivity", "destroyed"); super.onDestroy(); unbindService(mConnection); } @Override protected void onListItemClick(ListView listView, View view, int position, long id) { super.onListItemClick(listView, view, position, id); ListItem selectedItem = (ListItem) listView.getAdapter().getItem(position); Intent intent; if (selectedItem.getMarketType() != null) { intent = new Intent(this, MarketActivity.class); intent.putExtra(EVENT_ID, selectedItem.getId()); startActivityIfNeeded(intent, -1); } else if (selectedItem.getId() != -1) { intent = new Intent(this, EventListsActivity.class); intent.putExtra(EVENT_ID, selectedItem.getId()); startActivityIfNeeded(intent, -1); } else { Log.e("EventListsActivity", "unexpected item selected!"); } } @Override protected Dialog onCreateDialog(int id) { switch (id) { case (LOADING_DIALOG) : AlertDialog.Builder loadingDialog = new AlertDialog.Builder(this); loadingDialog.setTitle("Please Wait..."); loadingDialog.setMessage("Communicating with remote service."); return loadingDialog.create(); } return null; } private class EventsListTask extends AsyncTask<Integer, Void, LoginStatusEnum> { @Override protected void onPreExecute() { showDialog(LOADING_DIALOG); } @Override protected void onPostExecute(LoginStatusEnum loginStatusEnum) { dismissDialog(LOADING_DIALOG); if (loginStatusEnum != null) { switch (loginStatusEnum) { case OK: for (ListItem item : eventList) { listItemArrayAdapter.add(item); } listItemArrayAdapter.notifyDataSetChanged(); break; } } } @Override protected LoginStatusEnum doInBackground(Integer... params) { LoginStatusEnum result = LoginStatusEnum.OK; Integer eventId = params[0]; if (serviceBinder != null) { try { if (eventId == null || eventId == -1) { eventList = serviceBinder.getActiveEventTypes(); } else { eventList = serviceBinder.getEvents(eventId); } } catch (WebServiceException wse) { result = LoginStatusEnum.valueOf(wse.getMessage()); } } else { Log.e("EventListsActivity", "serviceBinder is null!"); } return result; } } } EDIT: The serviceBinder appears to be set to null when I reach the bottom of a list, when I change the target intent to go to a different activity: intent = new Intent(this, MarketActivity.class); intent.putExtra(EVENT_ID, selectedItem.getId()); startActivity(intent); This new activity also uses the same background service (binds in the same way, etc.). Is there anything I need to watch out for when doing this? Am I calling the target intent incorrectly? EDIT2: Here's the output from LogCat when I start the activity which calls the service (this time the service failed straight away!): 04-02 07:02:49.147: INFO/ActivityManager(61): Starting activity: Intent { cmp=net.foobar.activity/.EventListsActivity } 04-02 07:02:49.257: INFO/EventListsActivity(353): onCreate 04-02 07:02:49.426: INFO/EventListsActivity(353): service connected 04-02 07:02:49.437: ERROR/EventListsActivity(353): serviceBinder is null!

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• Purpose of lua_lock and lua_unlock?

  - by anon

  What is the point of lua_lock and lua_unlock? The following implies it's important: LUA_API void lua_gettable (lua_State *L, int idx) { StkId t; lua_lock(L); t = index2adr(L, idx); api_checkvalidindex(L, t); luaV_gettable(L, t, L->top - 1, L->top - 1); lua_unlock(L); } LUA_API void lua_getfield (lua_State *L, int idx, const char *k) { StkId t; TValue key; lua_lock(L); t = index2adr(L, idx); api_checkvalidindex(L, t); setsvalue(L, &key, luaS_new(L, k)); luaV_gettable(L, t, &key, L->top); api_incr_top(L); lua_unlock(L); } The following implies it does nothing: #define lua_lock(L) ((void) 0) #define lua_unlock(L) ((void) 0) Please enlighten.

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• Grails Unit Tests: Why does this statement fail?

  - by leeand00

  I've developed in Java in the past, and now I'm trying to learn Grails/Groovy using this slightly dated tutorial. import grails.test.* class DateTagLibTests extends TagLibUnitTestCase { def dateTagLib protected void setUp() { super.setUp() dateTagLib = new DateTagLib() } protected void tearDown() { super.tearDown() } void testThisYear() { String expected = Calendar.getInstance().get(Calendar.YEAR) // NOTE: This statement fails assertEquals("the years dont match and I dont know why.", expected, dateTagLib.thisYear()) } } DateTagLibTests.groovy (Note: this TagLibUnitTestCase is for Grails 1.2.1 and not the version used in the tutorial) For some reason the above test fails with: expected:<2010 but was:<2010 I've tried replacing the test above with the following alternate version of the test, and the test passes just fine: void testThisYear() { String expected = Calendar.getInstance().get(Calendar.YEAR) String actual = dateTagLib.thisYear() // NOTE: The following two assertions work: assertEquals("the years don\'t match", expected, actual) assertTrue("the years don\'t match", expected.equals(actual)) } These two versions of the test are basically the same thing right? Unless there's something new in Grails 1.2.1 or Groovy that I'm not understanding. They should be of the same type because the values are both the value returned by Calendar.getInstance().get(Calendar.YEAR)

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• Synchronizing issue: I want the main thread to be run before another thread but it sometimes doesn´t

  - by Rox

  I have done my own small concurrency framework (just for learning purposes) inspired by the java.util.concurrency package. This is about the Callable/Future mechanism. My code below is the whole one and is compilable and very easy to understand. My problem is that sometimes I run into a deadlock where the first thread (the main thread) awaits for a signal from the other thread. But then the other thread has already notified the main thread before the main thread went into waiting state, so the main thread cannot wake up. FutureTask.get() should always be run before FutureTask.run() but sometimes the run() method (which is called by new thread) runs before the get() method (which is called by main thread). I don´t know how I can prevent that. This is a pseudo code of how I want the two threads to be run. //From main thread: Executor.submit().get() (in get() the main thread waits for new thread to notify) ->submit() calls Executor.execute(FutureTask object) -> execute() starts new thread -> new thread shall notify `main thread` I cannot understand how the new thread can start up and run faster than the main thread that actually starts the new thread. Main.java: public class Main { public static void main(String[] args) { new ExecutorServiceExample(); } public Main() { ThreadExecutor executor = new ThreadExecutor(); Integer i = executor.submit(new Callable<Integer>() { @Override public Integer call() { return 10; } }).get(); System.err.println("Value: "+i); } } ThreadExecutor.java: public class ThreadExecutor { public ThreadExecutor() {} protected <V> RunnableFuture<V> newTaskFor(Callable c) { return new FutureTask<V>(c); } public <V> Future<V> submit(Callable<V> task) { if (task == null) throw new NullPointerException(); RunnableFuture<V> ftask = newTaskFor(task); execute(ftask); return ftask; } public void execute(Runnable r) { new Thread(r).start(); } } FutureTask.java: import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.ReentrantLock; import java.util.logging.Level; import java.util.logging.Logger; public class FutureTask<V> implements RunnableFuture<V> { private Callable<V> callable; private volatile V result; private ReentrantLock lock = new ReentrantLock(); private Condition condition = lock.newCondition(); public FutureTask(Callable callable) { if (callable == null) throw new NullPointerException(); this.callable = callable; } @Override public void run() { acquireLock(); System.err.println("RUN"+Thread.currentThread().getName()); V v = this.callable.call(); set(v); condition.signal(); releaseLock(); } @Override public V get() { acquireLock(); System.err.println("GET "+Thread.currentThread().getName()); try { condition.await(); } catch (InterruptedException ex) { Logger.getLogger(FutureTask.class.getName()).log(Level.SEVERE, null, ex); } releaseLock(); return this.result; } public void set(V v) { this.result = v; } private void acquireLock() { lock.lock(); } private void releaseLock() { lock.unlock(); } } And the interfaces: public interface RunnableFuture<V> extends Runnable, Future<V> { @Override void run(); } public interface Future<V> { V get(); } public interface Callable<V> { V call(); }

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• Socket server with multiple clients, sending messages to many clients without hurting liveliness

  - by Karl Johanson

  I have a small socket server, and I need to distribute various messages from client-to-client depending on different conditionals. However I think I have a small problem with livelyness in my current code, and is there anything wrong in my approach: public class CuClient extends Thread { Socket socket = null; ObjectOutputStream out; ObjectInputStream in; CuGroup group; public CuClient(Socket s, CuGroup g) { this.socket = s; this.group = g; out = new ObjectOutputStream(this.socket.getOutputStream()); out.flush(); in = new ObjectInputStream(this.socket.getInputStream()); } @Override public void run() { String cmd = ""; try { while (!cmd.equals("client shutdown")) { cmd = (String) in.readObject(); this.group.broadcastToGroup(this, cmd); } out.close(); in.close(); socket.close(); } catch (Exception e) { System.out.println(this.getName()); e.printStackTrace(); } } public void sendToClient(String msg) { try { this.out.writeObject(msg); this.out.flush(); } catch (IOException ex) { } } And my CuGroup: public class CuGroup { private Vector<CuClient> clients = new Vector<CuClient>(); public void addClient(CuClient c) { this.clients.add(c); } void broadcastToGroup(CuClient clientName, String cmd) { Iterator it = this.clients.iterator(); while (it.hasNext()) { CuClient cu = (CuClient)it.next(); cu.sendToClient(cmd); } } } And my main-class: public class SmallServer { public static final Vector<CuClient> clients = new Vector<CuClient>(10); public static boolean serverRunning = true; private ServerSocket serverSocket; private CuGroup group = new CuGroup(); public void body() { try { this.serverSocket = new ServerSocket(1337, 20); System.out.println("Waiting for clients\n"); do { Socket s = this.serverSocket.accept(); CuClient t = new CuClient(s,group); System.out.println("SERVER: " + s.getInetAddress() + " is connected!\n"); t.start(); } while (this.serverRunning); } catch (IOException ex) { ex.printStackTrace(); } } public static void main(String[] args) { System.out.println("Server"); SmallServer server = new SmallServer(); server.body(); } } Consider the example with many more groups, maybe a Collection of groups. If they all synchronize on a single Object, I don't think my server will be very fast. I there a pattern or something that can help my liveliness?

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