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• Wait during iPhone UI modification

  - by paul simmons

  Hi, I am making modifications to elements on UI. There is no (extra) thread or any async. calls. However I want to give a slow motion effect, so wait specific time at each step in a for loop. How can I achieve this without blocking the UI?

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• How might I schedule a C# Windows Service to perform a task daily?

  - by ctrlalt3nd

  I have a service written in C# (.NET 1.1) and want it to perform some cleanup actions at midnight every night. I have to keep all code contained within the service, so what's the easiest way to accomplish this? Use of Thread.Sleep() and checking for the time rolling over?

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• Synchronous database reads inside IHttpAsyncHandler

  - by sayao

  On asp.net if i call a synchronous database query inside an IHttpAsyncHandler with delegate.BeginInvoke, would it still release the asp.net worker thread while reading the database? For example, this post: http://madskristensen.net/post/How-to-use-the-IHttpAsyncHandler-in-ASPNET.aspx If i put a synchronous database call inside ServeContent, would the request still happen asynchronously?

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• Abnormally disconnected TCP sockets and write timeout

  - by James

  Hello I will try to explain the problem in shortest possible words. I am using c++ builder 2010. I am using TIdTCPServer and sending voice packets to a list of connected clients. Everything works ok untill any client is disconnected abnormally, For example power failure etc. I can reproduce similar disconnect by cutting the ethernet connection of a connected client. So now we have a disconnected socket but as you know it is not yet detected at server side so server will continue to try to send data to that client too. But when server try to write data to that disconnected client ...... Write() or WriteLn() HANGS there in trying to write, It is like it is wating for somekind of Write timeout. This hangs the hole packet distribution process as a result creating a lag in data transmission to all other clients. After few seconds "Socket Connection Closed" Exception is raised and data flow continues. Here is the code try { EnterCriticalSection(&SlotListenersCriticalSection); for(int i=0;i<SlotListeners->Count;i++) { try { //Here the process will HANG for several seconds on a disconnected socket ((TIdContext*) SlotListeners->Objects[i])->Connection->IOHandler->WriteLn("Some DATA"); }catch(Exception &e) { SlotListeners->Delete(i); } } }__finally { LeaveCriticalSection(&SlotListenersCriticalSection); } Ok i already have a keep alive mechanism which disconnect the socket after n seconds of inactivity. But as you can imagine, still this mechnism cant sync exactly with this braodcasting loop because this braodcasting loop is running almost all the time. So is there any Write timeouts i can specify may be through iohandler or something ? I have seen many many threads about "Detecting disconnected tcp socket" but my problem is little different, i need to avoid that hangup for few seconds during the write attempt. So is there any solution ? Or should i consider using some different mechanism for such data broadcasting for example the broadcasting loop put the data packet in some kind of FIFO buffer and client threads continuously check for available data and pick and deliver it to themselves ? This way if one thread hangs it will not stop/delay the over all distribution thread. Any ideas please ? Thanks for your time and help. Regards Jams

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• Is there any cross-platform threading library in C or C++?

  - by NumberFour

  Hello, I'm looking for some easy to use cross-platform threading library written in C or C++. What's your opinion on boost::thread or Pthreads? Does Pthreads run only on POSIX compliant systems? What about the threading support in the Qt library? Thanks for any hints.

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• How does JVM handles dynamic allocation

  - by Nile

  I want to understand how JVM manages heap for the dynamic allocations. Since every java program is invoked as a thread, when does JVM's garbage collector come into play. Also, how things work for javascript's dynamic allocation ?

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• Your creative PHP Obfuscation - Dynamic Variables

  - by Email

  Hi No thread about use or unuse of obfuscusion please ^^ Just share creative approaches how to obfuscate in php the really smart way plz. plain md5 and base64_decode is too static .. what you think regarding hash, salt what about dynamic Variables (even for the same $var). Thx for any creative input

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• How do I 'globally' catch exceptions thrown in object instances.

  - by SleepyBobos

  I am currently writing a winforms application (C#). I am making use of the Enterprise Library Exception Handling Block, following a fairly standard approach from what I can see. IE : In the Main method of Program.cs I have wired up event handler to Application.ThreadException event etc. This approach works well and handles the applications exceptional circumstances. In one of my business objects I throw various exceptions in the Set accessor of one of the objects properties set { if (value > MaximumTrim) throw new CustomExceptions.InvalidTrimValue("The value of the minimum trim..."); if (!availableSubMasterWidthSatisfiesAllPatterns(value)) throw new CustomExceptions.InvalidTrimValue("Another message..."); _minimumTrim = value; } My logic for this approach (without turning this into a 'when to throw exceptions' discussion) is simply that the business objects are responsible for checking business rule constraints and throwing an exception that can bubble up and be caught as required. It should be noted that in the UI of my application I do explictly check the values that the public property is being set to (and take action there displaying friendly dialog etc) but with throwing the exception I am also covering the situation where my business object may not be used by a UI eg : the Property is being set by another business object for example. Anyway I think you all get the idea. My issue is that these exceptions are not being caught by the handler wired up to Application.ThreadException and I don't understand why. From other reading I have done the Application.ThreadException event and it handler "... catches any exception that occurs on the main GUI thread". Are the exceptions being raised in my business object not in this thread? I have not created any new threads. I can get the approach to work if I update the code as follows, explicity calling the event handler that is wired to Application.ThreadException. This is the approach outlined in Enterprise Library samples. However this approach requires me to wrap any exceptions thrown in a try catch, something I was trying to avoid by using a 'global' handler to start with. try { if (value > MaximumTrim) throw new CustomExceptions.InvalidTrimValue("The value of the minimum..."); if (!availableSubMasterWidthSatisfiesAllPatterns(value)) throw new CustomExceptions.InvalidTrimValue("Another message"); _minimumTrim = value; } catch (Exception ex) { Program.ThreadExceptionHandler.ProcessUnhandledException(ex); } I have also investigated using wiring a handler up to AppDomain.UnhandledException event but this does not catch the exceptions either. I would be good if someone could explain to me why my exceptions are not being caught by my global exception handler in the first code sample. Is there another approach I am missing or am I stuck with wrapping code in try catch, shown above, as required?

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• Opengl-es android best way to preload images

  - by lacas

  I have a game app, and i have many screens. The first screen will be the SCREEN.LOADING screen. When the app starting, I want to show a picture "loading please wait" while the images, menus, etc loaded succesfull. I tried asynctask to do this, but its not work in GLThread. What is the way to do this in opengl-es? 03-06 12:46:35.282: ERROR/AndroidRuntime(32736): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() Thanks, Leslie

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• Fast response on first Socket I/O request but slow every other time when communicating with remote serial port

  - by GreenGodot

  I'm using sockets to pass Serial commands to a remote device. And the response to that request is sent back and printed out. However, I am having a problem in that the first time it is instant but the rest of the time it can take up to 20 seconds to receive a reply. I think the problem is with my attempt at threading but I am not entirely sure. new Thread() { @Override public void run() { System.out.println("opened"); try { isSocketRetrieving.setText("Opening Socket"); socket = new Socket(getAddress(), getRemotePort())); DataOutput = new DataOutputStream(socket .getOutputStream()); inFromServer = new BufferedReader( new InputStreamReader(socket .getInputStream())); String line = ""; isSocketRetrieving.setText("Reading Stream......"); while ((line = inFromServer.readLine()) != null) { System.out.println(line); if (line.contains(getHandshakeRequest())) { DataOutput.write((getHandshakeResponse()toString() + "\r").getBytes()); DataOutput.flush(); DataOutput .write((getCommand().toString() + "\r").getBytes()); DataOutput.flush(); int pause = (line.length()*8*1000)/getBaud(); sleep(pause); } else if (line.contains(readingObject .getExpected())) { System.out.println(line); textArea.append("value = " + line + "\n"); textAreaScroll.revalidate(); System.out.println("Got Value"); break; } } System.out.println("Ended"); try { inFromServer.close(); DataOutput.close(); socket.close(); isSocketRetrieving.setText("Socket is inactive..."); rs232Table.addMouseListener(listener); interrupt(); join(); } catch (IOException e) { e.printStackTrace(); } catch (InterruptedException e) { System.out.println("Thread exited"); } } catch (NumberFormatException e1) { e1.printStackTrace(); } catch (UnknownHostException e1) { e1.printStackTrace(); } catch (IOException e1) { e1.printStackTrace(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }.start();

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• how to show a UTC time as local time in a webpage

  - by Retrocoder

  I have a database that holds a time as UTC. This time can be shown in a webpage, so I’ve been asked to show it as local time in the page as it can be viewed from any country. A colleague mentioned something about getting the country settings from the current thread but I couldn’t find any details on this. Is what I want to do possible?

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• Does my TPL partitioner cause a deadlock?

  - by Scott Chamberlain

  I am starting to write my first parallel applications. This partitioner will enumerate over a IDataReader pulling chunkSize records at a time from the data-source. protected class DataSourcePartitioner<object[]> : System.Collections.Concurrent.Partitioner<object[]> { private readonly System.Data.IDataReader _Input; private readonly int _ChunkSize; public DataSourcePartitioner(System.Data.IDataReader input, int chunkSize = 10000) : base() { if (chunkSize < 1) throw new ArgumentOutOfRangeException("chunkSize"); _Input = input; _ChunkSize = chunkSize; } public override bool SupportsDynamicPartitions { get { return true; } } public override IList<IEnumerator<object[]>> GetPartitions(int partitionCount) { var dynamicPartitions = GetDynamicPartitions(); var partitions = new IEnumerator<object[]>[partitionCount]; for (int i = 0; i < partitionCount; i++) { partitions[i] = dynamicPartitions.GetEnumerator(); } return partitions; } public override IEnumerable<object[]> GetDynamicPartitions() { return new ListDynamicPartitions(_Input, _ChunkSize); } private class ListDynamicPartitions : IEnumerable<object[]> { private System.Data.IDataReader _Input; int _ChunkSize; private object _ChunkLock = new object(); public ListDynamicPartitions(System.Data.IDataReader input, int chunkSize) { _Input = input; _ChunkSize = chunkSize; } public IEnumerator<object[]> GetEnumerator() { while (true) { List<object[]> chunk = new List<object[]>(_ChunkSize); lock(_Input) { for (int i = 0; i < _ChunkSize; ++i) { if (!_Input.Read()) break; var values = new object[_Input.FieldCount]; _Input.GetValues(values); chunk.Add(values); } if (chunk.Count == 0) yield break; } var chunkEnumerator = chunk.GetEnumerator(); lock(_ChunkLock) //Will this cause a deadlock? { while (chunkEnumerator.MoveNext()) { yield return chunkEnumerator.Current; } } } } IEnumerator IEnumerable.GetEnumerator() { return ((IEnumerable<object[]>)this).GetEnumerator(); } } } I wanted IEnumerable object it passed back to be thread safe (the .Net example was so I am assuming PLINQ and TPL could need it) will the lock on _ChunkLock near the bottom help provide thread safety or will it cause a deadlock? From the documentation I could not tell if the lock would be released on the yeld return. Also if there is built in functionality to .net that will do what I am trying to do I would much rather use that. And if you find any other problems with the code I would appreciate it.

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• Running a Java program with input from a file

  - by Katy

  I am writing a program that reads the input from a file and then prints it to the screen. When I run it without taking the input from the file, it works perfectly fine. However, every time I try to run it from the file it gives me an "Exception in thread "main" java.util.NoSuchElementException: No line found at" error that occurs every place the input is suppose to be read. I have no idea what is going on.

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• Is MFC class CInternetConnection/CHttpConnection theadsafe.

  - by MattR

  I am pretty sure these classes are not thread safe. But, is it safe to use different objects from these classes in different threads? Do they have any global dependencies with each other like static data or anything to watch out for?

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• Linq to SQL: how get row security between write access??

  - by Francisco

  I would like to allow two threads to write in a table at the same time (I know the problem of updating the same row, but this would be a story apart). I need that in behalf of speed up the operations in my aplication (one thread could write in row X while another could do the same in row X+n instead of waiting the first to finalize). So, can I block rows instead of tables with Linq to SQL? Thanks.

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• Javascript: Writing a firefox extension with sockets

  - by Johnny Grass

  I need to write a firefox extension that creates a server socket (I think that's what it's called) and returns the browser's current url when a client application (running on the same computer) sends it a request. The thing is that I have no Java/Javascript background at all and I'm pressed for time so I am trying to hack something together from code samples. So far I've been mildly successful. I've been working with code from this question which is used in the open source Firefox exension PolyChrome I have the following code: var reader = { onInputStreamReady : function(input) { var input_stream = Components.classes["@mozilla.org/scriptableinputstream;1"] .createInstance(Components.interfaces.nsIScriptableInputStream); input_stream.init(input); input_stream.available(); var request = ''; while (input_stream.available()) { request = request + input_stream.read(512); } var checkString = "foo" if (request.toString() == checkString.toString()) { output_console('URL: ' + content.location.href); } else output_console("nothing"); var thread_manager = Components.classes["@mozilla.org/thread-manager;1"].getService(); input.asyncWait(reader,0,0,thread_manager.mainThread); } } var listener = { onSocketAccepted: function(serverSocket, clientSocket) { output_console("Accepted connection on "+clientSocket.host+":"+clientSocket.port); input = clientSocket.openInputStream(0, 0, 0).QueryInterface(Components.interfaces.nsIAsyncInputStream); output = clientSocket.openOutputStream(Components.interfaces.nsITransport.OPEN_BLOCKING, 0, 0); var thread_manager = Components.classes["@mozilla.org/thread-manager;1"].getService(); input.asyncWait(reader,0,0,thread_manager.mainThread); } } var serverSocket = Components.classes["@mozilla.org/network/server-socket;1"]. createInstance(Components.interfaces.nsIServerSocket); serverSocket.init(9999, true, 5); output_console("Opened socket on " + serverSocket.port); serverSocket.asyncListen(listener); I have a few questions. So far I can telnet into localhost and get a response, but my string comparison in the reader seems to fail even if I enter "foo". I don't get why. What am I missing? The sample code I'm using opens up a console window and prints output when I telnet into localhost. Ideally I would like the output to be returned as a response when the client sends a request to the server socket with a passphrase. How do I go about doing that? Is doing this a good idea? Does it create security vulnerabilities on the computer? How can I block connections to the socket from other computers? What is a good place to read about javascript sockets? My google searches have been pretty fruitless but then maybe I'm not using the right keywords.

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• Why is my platform variable defined as 'BNB'?

  - by Scott Langham

  Hi, Something, maybe the windows sdk or visual studio installer, has defined the Platform environment variable and given it the value BNB. What does BNB mean, and why is Platform set to BNB? Thanks. I've seen this, but it doesn't answer my question: http://social.msdn.microsoft.com/Forums/en-US/msbuild/thread/1d229d75-aa89-42bf-809b-ef98f42072bb

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• Execute another program in multi-threaded program

  - by Gary

  Hi, Just wondering how if it's possible to execute another program in a thread and send information to/get information from it. Essentially the same concept as with a child process and using pipes to communicate - however I don't want to use fork. I can't seem to find whether it's possible to do this, any help would be appreciated. Thanks

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• XmlSerializer.Deserialize blocks over NetworkStream

  - by Luca

  I'm trying to sends XML serializable objects over a network stream. I've already used this on an UDP broadcast server, where it receive UDP messages from the local network. Here a snippet of the server side: while (mServiceStopFlag == false) { if (mSocket.Available > 0) { IPEndPoint ipEndPoint = new IPEndPoint(IPAddress.Any, DiscoveryPort); byte[] bData; // Receive discovery message bData = mSocket.Receive(ref ipEndPoint); // Handle discovery message HandleDiscoveryMessage(ipEndPoint.Address, bData); ... Instead this is the client side: IPEndPoint ipEndPoint = new IPEndPoint(IPAddress.Broadcast, DiscoveryPort); MemoryStream mStream = new MemoryStream(); byte[] bData; // Create broadcast UDP server mSocket = new UdpClient(); mSocket.EnableBroadcast = true; // Create datagram data foreach (NetService s in ctx.Services) XmlHelper.SerializeClass<NetService>(mStream, s); bData = mStream.GetBuffer(); // Notify the services while (mServiceStopFlag == false) { mSocket.Send(bData, (int)mStream.Length, ipEndPoint); Thread.Sleep(DefaultServiceLatency); } It works very fine. But now i'me trying to get the same result, but on a TcpClient socket, but the using directly an XMLSerializer instance: On server side: TcpClient sSocket = k.Key; ServiceContext sContext = k.Value; Message msg = new Message(); while (sSocket.Connected == true) { if (sSocket.Available > 0) { StreamReader tr = new StreamReader(sSocket.GetStream()); msg = (Message)mXmlSerialize.Deserialize(tr); // Handle message msg = sContext.Handler(msg); // Reply with another message if (msg != null) mXmlSerialize.Serialize(sSocket.GetStream(), msg); } else Thread.Sleep(40); } And on client side: NetworkStream mSocketStream; Message rMessage; // Network stream mSocketStream = mSocket.GetStream(); // Send the message mXmlSerialize.Serialize(mSocketStream, msg); // Receive the answer rMessage = (Message)mXmlSerialize.Deserialize(mSocketStream); return (rMessage); The data is sent (Available property is greater then 0), but the method XmlSerialize.Deserialize (which should deserialize the Message class) blocks. What am I missing?

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• Multithreading, when to yield versus sleep

  - by aaa

  hello. To clarify terminology, yield is when thread gives up its time slice. My platform of interest is POSIX threads, but I think question is general. Suppose I have consumer/producer pattern. If I want to throttle either consumer or producer, which is better to use, sleep or yield? I am mostly interested in efficiency of using either function. Thanks

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• SQL Server 2008 takes up a lot of memory?

  - by Ahmed Said

  I am conducting stress tests on my database, which is hosted on SQL Server 2008 64-bit running on a 64-bit machine with 10 GB of RAM. I have 400 threads. Each thread queries the database every second, but the query time does not take time, as the SQL profiler says that, but after 18 hours SQL Server uses up 7.2 GB of RAM and 7.2 GB of virtual memory. Is this normal behavior? How can I adjust SQL Server to clean up unused memory?

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• Enterprise library not responding.

  - by Costa

  Hi I spent a day trying to make Ent Lib Logging work and log anything into database or event log, I have a web application and console application withe the same Ent Lib config, only the console is capable to log into the Event Log, I tried everything with permissions, but I don't know what exactly I am doing, which services should have what, It does not work!! HELP This is the config file which is automatically generated from Ent Lib utility and it works only on App.config, not on web.config <loggingConfiguration name="Logging Application Block" tracingEnabled="true" defaultCategory="General" logWarningsWhenNoCategoriesMatch="true" revertImpersonation="false"> <listeners> <add source="Logger" formatter="Text Formatter" log="Application" machineName="" listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FormattedEventLogTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" traceOutputOptions="None" filter="All" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FormattedEventLogTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" name="Formatted EventLog TraceListener" /> </listeners> <formatters> <add template="Timestamp: {timestamp}&#xD;&#xA;Message: {message}&#xD;&#xA;Category: {category}&#xD;&#xA;Priority: {priority}&#xD;&#xA;EventId: {eventid}&#xD;&#xA;Severity: {severity}&#xD;&#xA;Title:{title}&#xD;&#xA;Machine: {machine}&#xD;&#xA;Application Domain: {appDomain}&#xD;&#xA;Process Id: {processId}&#xD;&#xA;Process Name: {processName}&#xD;&#xA;Win32 Thread Id: {win32ThreadId}&#xD;&#xA;Thread Name: {threadName}&#xD;&#xA;Extended Properties: {dictionary({key} - {value}&#xD;&#xA;)}" type="Microsoft.Practices.EnterpriseLibrary.Logging.Formatters.TextFormatter, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" name="Text Formatter" /> </formatters> <categorySources> <add switchValue="All" name="General"> <listeners> <add name="Formatted EventLog TraceListener" /> </listeners> </add> </categorySources> <specialSources> <allEvents switchValue="All" name="All Events" /> <notProcessed switchValue="All" name="Unprocessed Category" /> <errors switchValue="All" name="Logging Errors &amp; Warnings"> <listeners> <add name="Formatted EventLog TraceListener" /> </listeners> </errors> </specialSources> </loggingConfiguration> thanks

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• Does it make sense to create a custom resource.xml instead of using asp.net's Resource .resx impleme

  - by Blankman

  I will be setting the current thread's culture at the beginning of the request lifecycle. Does it make sense if I create my own resource.xml to store things like strings/labels/messages that will be used in the web application? or are their drawbacks and its better if I just use the Global resources .resx files that are 'built-in' ?

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• NSManagedObjectContext returns YES for hasChanges when there are none

  - by JK

  I created a separate NSManagedObjectContext on a separate thread to perform some store maintenance. However, I have noticed that the context returns YES for hasChanges as soon as a managed object in it is even referenced e.g. NSString *name = managedObject.name; This context is created and used exclusively in 1 method. Why is it returning has changes, when there there are none?

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• Perfect Forwarding to async lambda

  - by Alexander Kondratskiy

  I have a function template, where I want to do perfect forwarding into a lambda that I run on another thread. Here is a minimal test case which you can directly compile: #include <thread> #include <future> #include <utility> #include <iostream> #include <vector> /** * Function template that does perfect forwarding to a lambda inside an * async call (or at least tries to). I want both instantiations of the * function to work (one for lvalue references T&, and rvalue reference T&&). * However, I cannot get the code to compile when calling it with an lvalue. * See main() below. */ template <typename T> std::string accessValueAsync(T&& obj) { std::future<std::string> fut = std::async(std::launch::async, [](T&& vec) mutable { return vec[0]; }, std::forward<T>(obj)); return fut.get(); } int main(int argc, char const *argv[]) { std::vector<std::string> lvalue{"Testing"}; // calling with what I assume is an lvalue reference does NOT compile std::cout << accessValueAsync(lvalue) << std::endl; // calling with rvalue reference compiles std::cout << accessValueAsync(std::move(lvalue)) << std::endl; // I want both to compile. return 0; } For the non-compiling case, here is the last line of the error message which is intelligible: main.cpp|13 col 29| note: no known conversion for argument 1 from ‘std::vector<std::basic_string<char> >’ to ‘std::vector<std::basic_string<char> >&’ I have a feeling it may have something to do with how T&& is deduced, but I can't pinpoint the exact point of failure and fix it. Any suggestions? Thank you! EDIT: I am using gcc 4.7.0 just in case this could be a compiler issue (probably not)

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