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  • Use server git installation in GitHub for Windows

    - by Lg102
    We are using Git as the version control for our website development. I work from a laptop, which is connected to the internal network via a WiFi connection. I've mapped the server drives as network drives in Windows. Commands such as git status take significantly longer for me than they do for my co-workers on wired connections. When connecting to the server using SSH and running commands on the git installation there, performance is even better. Is there a way to configure GitHub for Windows to use the server-installed git (with my credentials)? Note: While our production servers has a user configuration with proper permissions, the development server has only one root user.

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  • cd ~ dumps me in a seemingly empty directory

    - by Davidos
    This is on a Linux mint box. I'm told everywhere to use the command cd ~ To switch to the root directory before doing some command line magic. For some reason though, it dumps me in a directory named ~ where ls gives nothing and I can't get back to my home directory; I have to restart the terminal session to get out of the empty root directory. I'm positive that everything is just hidden to me, but even as a super-user I can't get the folders to show themselves. I usually just fall back to using a graphical file browser to roam those forbidden files, but I've recently just been shut out of my root directory, and the machine refuses to allow me to change the permissions on the stupid thing even when I type the root password in. It may just be some over-rigorous end-user shielding on the part of the mint team, but it's getting to be really frustrating now.

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  • Use `dd` linux program to save / recover a disk's MBR

    - by Graduate
    I have an Ubuntu OS installed on my laptop. I want to install Windows 7 as well to another disk partition (I will do it by recovering it from a special partition on my laptop). After installing Windows, I want to recover my hard drive MBR to be able to load Ubuntu. I have a plan to use linux dd program: 1) (Before installing, perform this command in Linux) dd if=/dev/sda of=/home/user/mbr_backup bs=512 count=1 2) (after installing, load Ubuntu Live CD and launch this) dd if=/home/user/mbr_backup of=/dev/sda bs=512 count=1 3) Load Ubuntu on PC and re-configure the GRUB2 to be able start Windows I need your advice, I want to be sure I won't damage the disk (it's partition table).

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  • Prevent email to root@domain

    - by kml
    I'm running Ubuntu Server 12.04 as a web server and use Exim4 for sending confirmation emails and such. Is there a way to set a system-wide email address for the root user? In other words, I'd like ALL email to go to a different address rather than [email protected]. For example, this command... echo "test" | mail -v -s test root ...would go to a different address, as well as all cron tasks that root executes: # m h dom mon dow user command 17 * * * * root cd / && run-parts --report /etc/cron.hourly 25 6 * * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily ) 47 6 * * 7 root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly ) 52 6 1 * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )

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  • VPN on PC vs Mac

    - by allstar
    I am trying to connect to a VPN from my home computer, as opposed to my work computer which already has the network info set up. I have received instructions on connecting from a mac, but since I don't have that I'm trying to do the equivalent on my PC. I know the: server group name secret and my own login account and password Using the Windows 7 VPN, there's space for: Internet address destination name user name password domain (optional) I'm trying to determine what's what. I assume the internet address is the server. I've tried using the "secret" as the Password, b/c i'd think the first part is connecting to the VPN as opposed to logging in. It still wants a user name though. I tried mine, I tried the "group name". I would appreciate your help with this. Thanks!

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  • Is there good FAT driver for FUSE? (Lightweight, not mountlo)

    - by Vi.
    FUSE filesystem list show some FuseFat and FatFuse. Both are old, FatFuse is read-only , FuseFat is non-buildable and probably depends on glib. Now I'm using mountlo for the task (mounting USB drives in generic way without root access or suid things (except of fusermount itself)), but it looks too big for such task. Using FUSE to mount external storage devices is good both for security and for flexibility reason: the kernel sees only block reads and writes while actual code that deals with filesystem details runs with user privileges, allowing user to use custom filesystems and preventing from kernel filesystem exploits. Is there good vfat FUSE driver?

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  • ssh tunnel through an intermediate host

    - by user1190650
    I have configured an SSH tunnel to forward my web traffic from hostA to hostC using this command on hostA: ssh -D 2222 user@hostC after configuring my browser to use a proxy on port 2222. This works great. However, I now want to forward the same traffic through an intermediate SSH connection on hostB in order to get to hostC. I tried this on hostA: ssh user@hostB -L 2222:hostB:22 but I get "channel x: open failed" errors. Does anyone know the correct way of doing this?

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  • How Can I Find My Windows 7 Pro Product Key is Original?

    - by user29373
    Our Company Wants to buy 30 windows 7 pro OEM License. and somebody gave us some package like this http://www.citymax.co.nz/45-91-thickbox/windows-7-professional-oem.jpg 1- I want to know that Does this Windows 7 Pro Package is Original and genuine?How can I sure that? 2- How Can I understand how many user can use this Windows? He gave us for 30 client but what happen if we install this package for more than that? How can I find the number of user can install this? 3- How can I check the Product Key before installing Windows? Has microsoft site for checking product key?

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  • win 8.1 with two startup logins. One local and one microsoft account

    - by lantonis
    On my win 8 pc when the pc was turned on i disabled the login password and it autogone to the start. After i updated to win 8.1 it first takes me to a login and its not set to me microsoft account but as other user. Thus is fails to login and i have to click below login as a microsoft account and reenter everytime my email and password. In windows in users there is only one user and thats the one i had before. No local account set or something. Same to accounts in control panel. How do i disable this double accounts?

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  • How to write a test for accounts controller for forms authenticate

    - by Anil Ali
    Trying to figure out how to adequately test my accounts controller. I am having problem testing the successful logon scenario. Issue 1) Am I missing any other tests.(I am testing the model validation attributes separately) Issue 2) Put_ReturnsOverviewRedirectToRouteResultIfLogonSuccessAndNoReturnUrlGiven() and Put_ReturnsRedirectResultIfLogonSuccessAndReturnUrlGiven() test are not passing. I have narrowed it down to the line where i am calling _membership.validateuser(). Even though during my mock setup of the service i am stating that i want to return true whenever validateuser is called, the method call returns false. Here is what I have gotten so far AccountController.cs [HandleError] public class AccountController : Controller { private IMembershipService _membershipService; public AccountController() : this(null) { } public AccountController(IMembershipService membershipService) { _membershipService = membershipService ?? new AccountMembershipService(); } [HttpGet] public ActionResult LogOn() { return View(); } [HttpPost] public ActionResult LogOn(LogOnModel model, string returnUrl) { if (ModelState.IsValid) { if (_membershipService.ValidateUser(model.UserName,model.Password)) { if (!String.IsNullOrEmpty(returnUrl)) { return Redirect(returnUrl); } return RedirectToAction("Index", "Overview"); } ModelState.AddModelError("*", "The user name or password provided is incorrect."); } return View(model); } } AccountServices.cs public interface IMembershipService { bool ValidateUser(string userName, string password); } public class AccountMembershipService : IMembershipService { public bool ValidateUser(string userName, string password) { throw new System.NotImplementedException(); } } AccountControllerFacts.cs public class AccountControllerFacts { public static AccountController GetAccountControllerForLogonSuccess() { var membershipServiceStub = MockRepository.GenerateStub<IMembershipService>(); var controller = new AccountController(membershipServiceStub); membershipServiceStub .Stub(x => x.ValidateUser("someuser", "somepass")) .Return(true); return controller; } public static AccountController GetAccountControllerForLogonFailure() { var membershipServiceStub = MockRepository.GenerateStub<IMembershipService>(); var controller = new AccountController(membershipServiceStub); membershipServiceStub .Stub(x => x.ValidateUser("someuser", "somepass")) .Return(false); return controller; } public class LogOn { [Fact] public void Get_ReturnsViewResultWithDefaultViewName() { // Arrange var controller = GetAccountControllerForLogonSuccess(); // Act var result = controller.LogOn(); // Assert Assert.IsType<ViewResult>(result); Assert.Empty(((ViewResult)result).ViewName); } [Fact] public void Put_ReturnsOverviewRedirectToRouteResultIfLogonSuccessAndNoReturnUrlGiven() { // Arrange var controller = GetAccountControllerForLogonSuccess(); var user = new LogOnModel(); // Act var result = controller.LogOn(user, null); var redirectresult = (RedirectToRouteResult) result; // Assert Assert.IsType<RedirectToRouteResult>(result); Assert.Equal("Overview", redirectresult.RouteValues["controller"]); Assert.Equal("Index", redirectresult.RouteValues["action"]); } [Fact] public void Put_ReturnsRedirectResultIfLogonSuccessAndReturnUrlGiven() { // Arrange var controller = GetAccountControllerForLogonSuccess(); var user = new LogOnModel(); // Act var result = controller.LogOn(user, "someurl"); var redirectResult = (RedirectResult) result; // Assert Assert.IsType<RedirectResult>(result); Assert.Equal("someurl", redirectResult.Url); } [Fact] public void Put_ReturnsViewIfInvalidModelState() { // Arrange var controller = GetAccountControllerForLogonFailure(); var user = new LogOnModel(); controller.ModelState.AddModelError("*","Invalid model state."); // Act var result = controller.LogOn(user, "someurl"); var viewResult = (ViewResult) result; // Assert Assert.IsType<ViewResult>(result); Assert.Empty(viewResult.ViewName); Assert.Same(user,viewResult.ViewData.Model); } [Fact] public void Put_ReturnsViewIfLogonFailed() { // Arrange var controller = GetAccountControllerForLogonFailure(); var user = new LogOnModel(); // Act var result = controller.LogOn(user, "someurl"); var viewResult = (ViewResult) result; // Assert Assert.IsType<ViewResult>(result); Assert.Empty(viewResult.ViewName); Assert.Same(user,viewResult.ViewData.Model); Assert.Equal(false,viewResult.ViewData.ModelState.IsValid); } } }

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  • Example map-reduce oozie program not working on CDH 4.5

    - by user2002748
    I am using Hadoop (CDH 4.5) on my mac since some time now, and do run map reduce jobs regularly. I installed oozie recently (again, CDH4.5) following instructions at: http://archive.cloudera.com/cdh4/cdh/4/oozie-3.3.2-cdh4.5.0/DG_QuickStart.html, and tried to run sample programs provided. However, it always fails with the following error. Looks like the workflow is not getting run at all. The Console URL field in the Job info is also empty. Could someone please help on this? The relevant snippet of the Oozie Job log follows. 2014-06-10 17:27:18,414 INFO ActionStartXCommand:539 - USER[userXXX] GROUP[-] TOKEN[] APP[map-reduce-wf] JOB[0000000-140610172702069-oozie-usrX-W] ACTION[0000000-140610172702069-oozie-usrX-W@:start:] Start action [0000000-140610172702069-oozie-usrX-W@:start:] with user-retry state : userRetryCount [0], userRetryMax [0], userRetryInterval [10] 2014-06-10 17:27:18,417 WARN ActionStartXCommand:542 - USER[userXXX] GROUP[-] TOKEN[] APP[map-reduce-wf] JOB[0000000-140610172702069-oozie-usrX-W] ACTION[0000000-140610172702069-oozie-usrX-W@:start:] [***0000000-140610172702069-oozie-usrX-W@:start:***]Action status=DONE 2014-06-10 17:27:18,417 WARN ActionStartXCommand:542 - USER[userXXX] GROUP[-] TOKEN[] APP[map-reduce-wf] JOB[0000000-140610172702069-oozie-usrX-W] ACTION[0000000-140610172702069-oozie-usrX-W@:start:] [***0000000-140610172702069-oozie-usrX-W@:start:***]Action updated in DB! 2014-06-10 17:27:18,576 INFO ActionStartXCommand:539 - USER[userXXX] GROUP[-] TOKEN[] APP[map-reduce-wf] JOB[0000000-140610172702069-oozie-usrX-W] ACTION[0000000-140610172702069-oozie-usrX-W@mr-node] Start action [0000000-140610172702069-oozie-usrX-W@mr-node] with user-retry state : userRetryCount [0], userRetryMax [0], userRetryInterval [10] 2014-06-10 17:27:19,188 WARN MapReduceActionExecutor:542 - USER[userXXX] GROUP[-] TOKEN[] APP[map-reduce-wf] JOB[0000000-140610172702069-oozie-usrX-W] ACTION[0000000-140610172702069-oozie-usrX-W@mr-node] credentials is null for the action 2014-06-10 17:27:19,423 WARN ActionStartXCommand:542 - USER[userXXX] GROUP[-] TOKEN[] APP[map-reduce-wf] JOB[0000000-140610172702069-oozie-usrX-W] ACTION[0000000-140610172702069-oozie-usrX-W@mr-node] Error starting action [mr-node]. ErrorType [TRANSIENT], ErrorCode [JA009], Message [JA009: Unknown rpc kind RPC_WRITABLE] org.apache.oozie.action.ActionExecutorException: JA009: Unknown rpc kind RPC_WRITABLE at org.apache.oozie.action.ActionExecutor.convertExceptionHelper(ActionExecutor.java:418) at org.apache.oozie.action.ActionExecutor.convertException(ActionExecutor.java:392) at org.apache.oozie.action.hadoop.JavaActionExecutor.submitLauncher(JavaActionExecutor.java:773) at org.apache.oozie.action.hadoop.JavaActionExecutor.start(JavaActionExecutor.java:927) at org.apache.oozie.command.wf.ActionStartXCommand.execute(ActionStartXCommand.java:211) at org.apache.oozie.command.wf.ActionStartXCommand.execute(ActionStartXCommand.java:59) at org.apache.oozie.command.XCommand.call(XCommand.java:277) at org.apache.oozie.service.CallableQueueService$CompositeCallable.call(CallableQueueService.java:326) at org.apache.oozie.service.CallableQueueService$CompositeCallable.call(CallableQueueService.java:255) at org.apache.oozie.service.CallableQueueService$CallableWrapper.run(CallableQueueService.java:175) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:744) Caused by: org.apache.hadoop.ipc.RemoteException(java.io.IOException): Unknown rpc kind RPC_WRITABLE at org.apache.hadoop.ipc.Client.call(Client.java:1238) at org.apache.hadoop.ipc.WritableRpcEngine$Invoker.invoke(WritableRpcEngine.java:225) at org.apache.hadoop.mapred.$Proxy30.getDelegationToken(Unknown Source) at org.apache.hadoop.mapred.JobClient.getDelegationToken(JobClient.java:2125) at org.apache.oozie.service.HadoopAccessorService.createJobClient(HadoopAccessorService.java:372) at org.apache.oozie.action.hadoop.JavaActionExecutor.createJobClient(JavaActionExecutor.java:970) at org.apache.oozie.action.hadoop.JavaActionExecutor.submitLauncher(JavaActionExecutor.java:723) ... 10 more 2014-06-10 17:27:19,426 INFO ActionStartXCommand:539 - USER[userXXX] GROUP[-] TOKEN[] APP[map-reduce-wf] JOB[0000000-140610172702069-oozie-usrX-W] ACTION[0000000-140610172702069-oozie-usrX-W@mr-node] Next Retry, Attempt Number [1] in [60,000] milliseconds 2014-06-10 17:28:19,468 INFO ActionStartXCommand:539 - USER[userXXX] GROUP[-] TOKEN[] APP[map-reduce-wf] JOB[0000000-140610172702069-oozie-usrX-W] ACTION[0000000-140610172702069-oozie-usrX-W@mr-node] Start action [0000000-140610172702069-oozie-usrX-W@mr-node] with user-retry state : userRetryCount [0], userRetryMax [0], userRetryInterval [10]

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  • Getting WCF Bindings and Behaviors from any config source

    - by cibrax
    The need of loading WCF bindings or behaviors from different sources such as files in a disk or databases is a common requirement when dealing with configuration either on the client side or the service side. The traditional way to accomplish this in WCF is loading everything from the standard configuration section (serviceModel section) or creating all the bindings and behaviors by hand in code. However, there is a solution in the middle that becomes handy when more flexibility is needed. This solution involves getting the configuration from any place, and use that configuration to automatically configure any existing binding or behavior instance created with code.  In order to configure a binding instance (System.ServiceModel.Channels.Binding) that you later inject in any endpoint on the client channel or the service host, you first need to get a binding configuration section from any configuration file (you can generate a temp file on the fly if you are using any other source for storing the configuration).  private BindingsSection GetBindingsSection(string path) { System.Configuration.Configuration config = System.Configuration.ConfigurationManager.OpenMappedExeConfiguration( new System.Configuration.ExeConfigurationFileMap() { ExeConfigFilename = path }, System.Configuration.ConfigurationUserLevel.None); var serviceModel = ServiceModelSectionGroup.GetSectionGroup(config); return serviceModel.Bindings; }   The BindingsSection contains a list of all the configured bindings in the serviceModel configuration section, so you can iterate through all the configured binding that get the one you need (You don’t need to have a complete serviceModel section, a section with the bindings only works).  public Binding ResolveBinding(string name) { BindingsSection section = GetBindingsSection(path); foreach (var bindingCollection in section.BindingCollections) { if (bindingCollection.ConfiguredBindings.Count > 0 && bindingCollection.ConfiguredBindings[0].Name == name) { var bindingElement = bindingCollection.ConfiguredBindings[0]; var binding = (Binding)Activator.CreateInstance(bindingCollection.BindingType); binding.Name = bindingElement.Name; bindingElement.ApplyConfiguration(binding); return binding; } } return null; }   The code above does just that, and also instantiates and configures the Binding object (System.ServiceModel.Channels.Binding) you are looking for. As you can see, the binding configuration element contains a method “ApplyConfiguration” that receives the binding instance that needs to be configured. A similar thing can be done for instance with the “Endpoint” behaviors. You first get the BehaviorsSection, and then, the behavior you want to use.  private BehaviorsSection GetBehaviorsSection(string path) { System.Configuration.Configuration config = System.Configuration.ConfigurationManager.OpenMappedExeConfiguration( new System.Configuration.ExeConfigurationFileMap() { ExeConfigFilename = path }, System.Configuration.ConfigurationUserLevel.None); var serviceModel = ServiceModelSectionGroup.GetSectionGroup(config); return serviceModel.Behaviors; }public List<IEndpointBehavior> ResolveEndpointBehavior(string name) { BehaviorsSection section = GetBehaviorsSection(path); List<IEndpointBehavior> endpointBehaviors = new List<IEndpointBehavior>(); if (section.EndpointBehaviors.Count > 0 && section.EndpointBehaviors[0].Name == name) { var behaviorCollectionElement = section.EndpointBehaviors[0]; foreach (BehaviorExtensionElement behaviorExtension in behaviorCollectionElement) { object extension = behaviorExtension.GetType().InvokeMember("CreateBehavior", BindingFlags.InvokeMethod | BindingFlags.NonPublic | BindingFlags.Instance, null, behaviorExtension, null); endpointBehaviors.Add((IEndpointBehavior)extension); } return endpointBehaviors; } return null; }   In this case, the code for creating the behavior instance is more tricky. First of all, a behavior in the configuration section actually represents a set of “IEndpoint” behaviors, and the behavior element you get from the configuration does not have any public method to configure an existing behavior instance. This last one only contains a protected method “CreateBehavior” that you can use for that purpose. Once you get this code implemented, a client channel can be easily configured as follows  var binding = resolver.ResolveBinding("MyBinding"); var behaviors = resolver.ResolveEndpointBehavior("MyBehavior"); SampleServiceClient client = new SampleServiceClient(binding, new EndpointAddress(new Uri("http://localhost:13749/SampleService.svc"), new DnsEndpointIdentity("localhost"))); foreach (var behavior in behaviors) { if(client.Endpoint.Behaviors.Contains(behavior.GetType())) { client.Endpoint.Behaviors.Remove(behavior.GetType()); } client.Endpoint.Behaviors.Add(behavior); }   The code above assumes that a configuration file (in any place) with a binding “MyBinding” and a behavior “MyBehavior” exists. That file can look like this,  <system.serviceModel> <bindings> <basicHttpBinding> <binding name="MyBinding"> <security mode="Transport"></security> </binding> </basicHttpBinding> </bindings> <behaviors> <endpointBehaviors> <behavior name="MyBehavior"> <clientCredentials> <windows/> </clientCredentials> </behavior> </endpointBehaviors> </behaviors> </system.serviceModel>   The same thing can be done of course in the service host if you want to manually configure the bindings and behaviors.  

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  • Classes / instances in Ontology

    - by SODA
    Hi, I'm trying to comprehend ontology basics. Here's an example: car (class) 2009 VW CC (sub-class or instance?) My neighbor's 2009 VW CC (instance) My issue is understanding what is "2009 VW CC" (as a car model). If you're making product model a sub-class in the ontology - all of a sudden your ontology becomes bloated with thousands of subclasses of a "car". That's redundant. At the same time we can't say "2009 VW CC" is an instance, at least it's not material instance of a class. Does it make sense to distinguish between regular instances and material (distinct physical objects)? At the other hand, if both are instances (of different nature so to say), then how can instance inherit properties / relations of a non-class?

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  • Boost C++ Singleton error LNK2001: unresolved external symbol "private: static long Nsp::HL::flag" (

    - by Soós Roland
    I try to create a multi-threaded singleton pattern class. Header: class HL{ public: static HL* getInstance(); ......... private: static HL* instance; static boost::once_flag flag; HL(); static void initOnce(); } CPP: HL* HL::instance = NULL; HL* HL::getInstance(){ if(instance == NULL){ boost::call_once(flag, initOnce); } return instance; } void HL::initOnce(){ instance = new HL(); } I get this error: error LNK2001: unresolved external symbol "private: static long Nsp::HL::flag" (?flag@HL@Nsp@@0JA) What's wrong?

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  • Subterranean IL: Constructor constraints

    - by Simon Cooper
    The constructor generic constraint is a slightly wierd one. The ECMA specification simply states that it: constrains [the type] to being a concrete reference type (i.e., not abstract) that has a public constructor taking no arguments (the default constructor), or to being a value type. There seems to be no reference within the spec to how you actually create an instance of a generic type with such a constraint. In non-generic methods, the normal way of creating an instance of a class is quite different to initializing an instance of a value type. For a reference type, you use newobj: newobj instance void IncrementableClass::.ctor() and for value types, you need to use initobj: .locals init ( valuetype IncrementableStruct s1 ) ldloca 0 initobj IncrementableStruct But, for a generic method, we need a consistent method that would work equally well for reference or value types. Activator.CreateInstance<T> To solve this problem the CLR designers could have chosen to create something similar to the constrained. prefix; if T is a value type, call initobj, and if it is a reference type, call newobj instance void !!0::.ctor(). However, this solution is much more heavyweight than constrained callvirt. The newobj call is encoded in the assembly using a simple reference to a row in a metadata table. This encoding is no longer valid for a call to !!0::.ctor(), as different constructor methods occupy different rows in the metadata tables. Furthermore, constructors aren't virtual, so we would have to somehow do a dynamic lookup to the correct method at runtime without using a MethodTable, something which is completely new to the CLR. Trying to do this in IL results in the following verification error: newobj instance void !!0::.ctor() [IL]: Error: Unable to resolve token. This is where Activator.CreateInstance<T> comes in. We can call this method to return us a new T, and make the whole issue Somebody Else's Problem. CreateInstance does all the dynamic method lookup for us, and returns us a new instance of the correct reference or value type (strangely enough, Activator.CreateInstance<T> does not itself have a .ctor constraint on its generic parameter): .method private static !!0 CreateInstance<.ctor T>() { call !!0 [mscorlib]System.Activator::CreateInstance<!!0>() ret } Going further: compiler enhancements Although this method works perfectly well for solving the problem, the C# compiler goes one step further. If you decompile the C# version of the CreateInstance method above: private static T CreateInstance() where T : new() { return new T(); } what you actually get is this (edited slightly for space & clarity): .method private static !!T CreateInstance<.ctor T>() { .locals init ( [0] !!T CS$0$0000, [1] !!T CS$0$0001 ) DetectValueType: ldloca.s 0 initobj !!T ldloc.0 box !!T brfalse.s CreateInstance CreateValueType: ldloca.s 1 initobj !!T ldloc.1 ret CreateInstance: call !!0 [mscorlib]System.Activator::CreateInstance<T>() ret } What on earth is going on here? Looking closer, it's actually quite a clever performance optimization around value types. So, lets dissect this code to see what it does. The CreateValueType and CreateInstance sections should be fairly self-explanatory; using initobj for value types, and Activator.CreateInstance for reference types. How does the DetectValueType section work? First, the stack transition for value types: ldloca.s 0 // &[!!T(uninitialized)] initobj !!T // ldloc.0 // !!T box !!T // O[!!T] brfalse.s // branch not taken When the brfalse.s is hit, the top stack entry is a non-null reference to a boxed !!T, so execution continues to to the CreateValueType section. What about when !!T is a reference type? Remember, the 'default' value of an object reference (type O) is zero, or null. ldloca.s 0 // &[!!T(null)] initobj !!T // ldloc.0 // null box !!T // null brfalse.s // branch taken Because box on a reference type is a no-op, the top of the stack at the brfalse.s is null, and so the branch to CreateInstance is taken. For reference types, Activator.CreateInstance is called which does the full dynamic lookup using reflection. For value types, a simple initobj is called, which is far faster, and also eliminates the unboxing that Activator.CreateInstance has to perform for value types. However, this is strictly a performance optimization; Activator.CreateInstance<T> works for value types as well as reference types. Next... That concludes the initial premise of the Subterranean IL series; to cover the details of generic methods and generic code in IL. I've got a few other ideas about where to go next; however, if anyone has any itching questions, suggestions, or things you've always wondered about IL, do let me know.

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  • TFS and working with multiple solutions

    - by RandomEngy
    How do people generally deal with TFS when you've got to work with multiple solution files? If you've got one instance it's easy because you can always go to that window for the source control explorer, pending changes, check on builds or work items. But when you have 4-5 solutions, it becomes tricky to deal with. You might expand some folders or check some pending items on one VS instance but you have to remember which one you did it on. Having a separate instance dedicated just to TFS tasks is tempting, but there's only one window state for the whole program. If that instance is closed last, all instances will come up with all the TFS windows open. How do other people deal with this? Can you use separate profiles somehow and cordon off a "TFS" instance of Visual Studio?

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  • Calling a method from within a django model save() override

    - by Jonathan
    I'm overriding a django model save() method. Within the override I'm calling another method of the same class and instance which calculates one of the instance's fields based on other fields of the same instance. class MyClass(models.Model): field1 = models.FloatField() field2 = models.FloatField() field3 = models.FloatField() def calculateField1(self) self.field1 = self.field2 + self.field3 def save(self, *args, **kwargs): self.calculateField1() super(MyClass, self).save(*args, **kwargs) The override method is called when I change the model in admin. Alas I've discovered that within calculateField1() field2 and field3 have the values of the instance from before I edited them in admin. If I enter the instance again in admin and save again, only then field1 receives the correct value as field2 and field3 are already updated. Is this the correct behavior on django's side? If yes, then how can I use the new values within calculateField1? I cannot implement the calculation within the save() as calculateField1() actually quite long and I need it to be called from elsewhere.

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  • Why enumerator structs are a really bad idea

    - by Simon Cooper
    If you've ever poked around the .NET class libraries in Reflector, I'm sure you would have noticed that the generic collection classes all have implementations of their IEnumerator as a struct rather than a class. As you will see, this design decision has some rather unfortunate side effects... As is generally known in the .NET world, mutable structs are a Very Bad Idea; and there are several other blogs around explaining this (Eric Lippert's blog post explains the problem quite well). In the BCL, the generic collection enumerators are all mutable structs, as they need to keep track of where they are in the collection. This bit me quite hard when I was coding a wrapper around a LinkedList<int>.Enumerator. It boils down to this code: sealed class EnumeratorWrapper : IEnumerator<int> { private readonly LinkedList<int>.Enumerator m_Enumerator; public EnumeratorWrapper(LinkedList<int> linkedList) { m_Enumerator = linkedList.GetEnumerator(); } public int Current { get { return m_Enumerator.Current; } } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { return m_Enumerator.MoveNext(); } public void Reset() { ((System.Collections.IEnumerator)m_Enumerator).Reset(); } public void Dispose() { m_Enumerator.Dispose(); } } The key line here is the MoveNext method. When I initially coded this, I thought that the call to m_Enumerator.MoveNext() would alter the enumerator state in the m_Enumerator class variable and so the enumeration would proceed in an orderly fashion through the collection. However, when I ran this code it went into an infinite loop - the m_Enumerator.MoveNext() call wasn't actually changing the state in the m_Enumerator variable at all, and my code was looping forever on the first collection element. It was only after disassembling that method that I found out what was going on The MoveNext method above results in the following IL: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000, [1] valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator CS$0$0001) L_0000: nop L_0001: ldarg.0 L_0002: ldfld valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: stloc.1 L_0008: ldloca.s CS$0$0001 L_000a: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000f: stloc.0 L_0010: br.s L_0012 L_0012: ldloc.0 L_0013: ret } Here, the important line is 0002 - m_Enumerator is accessed using the ldfld operator, which does the following: Finds the value of a field in the object whose reference is currently on the evaluation stack. So, what the MoveNext method is doing is the following: public bool MoveNext() { LinkedList<int>.Enumerator CS$0$0001 = this.m_Enumerator; bool CS$1$0000 = CS$0$0001.MoveNext(); return CS$1$0000; } The enumerator instance being modified by the call to MoveNext is the one stored in the CS$0$0001 variable on the stack, and not the one in the EnumeratorWrapper class instance. Hence why the state of m_Enumerator wasn't getting updated. Hmm, ok. Well, why is it doing this? If you have a read of Eric Lippert's blog post about this issue, you'll notice he quotes a few sections of the C# spec. In particular, 7.5.4: ...if the field is readonly and the reference occurs outside an instance constructor of the class in which the field is declared, then the result is a value, namely the value of the field I in the object referenced by E. And my m_Enumerator field is readonly! Indeed, if I remove the readonly from the class variable then the problem goes away, and the code works as expected. The IL confirms this: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000) L_0000: nop L_0001: ldarg.0 L_0002: ldflda valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000c: stloc.0 L_000d: br.s L_000f L_000f: ldloc.0 L_0010: ret } Notice on line 0002, instead of the ldfld we had before, we've got a ldflda, which does this: Finds the address of a field in the object whose reference is currently on the evaluation stack. Instead of loading the value, we're loading the address of the m_Enumerator field. So now the call to MoveNext modifies the enumerator stored in the class rather than on the stack, and everything works as expected. Previously, I had thought enumerator structs were an odd but interesting feature of the BCL that I had used in the past to do linked list slices. However, effects like this only underline how dangerous mutable structs are, and I'm at a loss to explain why the enumerators were implemented as structs in the first place. (interestingly, the SortedList<TKey, TValue> enumerator is a struct but is private, which makes it even more odd - the only way it can be accessed is as a boxed IEnumerator!). I would love to hear people's theories as to why the enumerators are implemented in such a fashion. And bonus points if you can explain why LinkedList<int>.Enumerator.Reset is an explicit implementation but Dispose is implicit... Note to self: never ever ever code a mutable struct.

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  • Django: way to test what class a generic relation content_object is?

    - by bitbutter
    In my project I have a class, NewsItem. Instances of NewsItem act like a wrapper. They can be associated with either an ArtWork instance, or an Announcement instance. Here's how the NewsItem model looks: class NewsItem(models.Model): content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type', 'object_id') date = models.DateTimeField(default=datetime.datetime.now,) class Meta: ordering = ('-date',) def __unicode__(self): return (self.title()) In a template I'm dealing with a NewsItem instance, and would like to output a certain bunch of html it it's 'wrapping' an Artwork instance, and a different bunch of html if it's wrapping an Announcement instance. Could someone explain how I can write a conditional to test for this? My first naive try looked like this: {% if news_item.content_object.type=='Artwork' %}do this{% else %}do that{% endif %}

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  • SSIS process files from folder

    - by RT
    Background: I've a folder that gets pumped with files continuously. My SSIS package needs to process the files and delete them. The SSIS package is scheduled to run once every minute. I'm picking up the files in ascending order of file creation time. I'm building an array of files and then processing-deleting them one at a time. Problem: If an instance of my package takes longer than one minute to run, the next instance of the SSIS package will pick up some of the files the previous instance has in its buffer. By the time the second instance of teh package gets around to processing a file, it may already have been deleted by the first instance, creating an exception condition. I was wondering whether there was a way to avoid the exception condition. Thanks.

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  • Haskell: variant of `show` that doesn't wrap String and Char in quotes

    - by Joey Adams
    I'd like a variant of show (let's call it label) that acts just like show, except that it doesn't wrap Strings in " " or Chars in ' '. Examples: > label 5 "5" > label "hello" "hello" > label 'c' "c" I tried implementing this manually, but I ran into some walls. Here is what I tried: {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE UndecidableInstances #-} module Label where class (Show a) => Label a where label :: a -> String instance Label [Char] where label str = str instance Label Char where label c = [c] -- Default case instance Show a => Label a where label x = show x However, because the default case's class overlaps instance Label [Char] and instance Label Char, those types don't work with the label function. Is there a library function that provides this functionality? If not, is there a workaround to get the above code to work?

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  • How can I simulate the effects of an observable collection in this situation?

    - by MGSoto
    I am making a configuration editor for another application and am using reflection to pull editable fields from the configuration class. The following class is the base class for my various "DataTypeViewModels" and shows how I get and set the appropriate properties. public abstract class DataTypeViewModel<T> : ViewModelBase { Func<T> getFunction; Action<T> setAction; public const string ValuePropertyName = "Value"; public string Label { get; set; } public T Value { get { return getFunction.Invoke(); } set { if (getFunction.Invoke().Equals(value)) { return; } setAction.Invoke(value); // Update bindings, no broadcast RaisePropertyChanged(ValuePropertyName); } } /// <summary> /// Initializes a new instance of the StringViewModel class. /// </summary> public DataTypeViewModel(string sectionName, string label) { if (IsInDesignMode) { // Code runs in Blend --> create design time data. } else { Label = label; getFunction = new Func<T>(() => { return (T)Settings.Instance.GetType().GetProperty(sectionName).PropertyType. GetProperty(label).GetValue(Settings.Instance.GetType().GetProperty(sectionName).GetValue(Settings.Instance, null), null); }); setAction = new Action<T>(value => { Settings.Instance.GetType().GetProperty(sectionName).PropertyType.GetProperty(label). SetValue(Settings.Instance.GetType().GetProperty(sectionName).GetValue(Settings.Instance, null), value, null); }); } } } This part works the way I want it to, the next part is a sample DataTypeViewModel on a list of strings. public class StringListViewModel : DataTypeViewModel<ICollection<string>> { /// <summary> /// The <see cref="RemoveItemCommand" /> property's name. /// </summary> public const string RemoveItemCommandPropertyName = "RemoveItemCommand"; private RelayCommand<string> _removeItemCommand = null; public ObservableCollection<string> ObservableValue { get; set; } /// <summary> /// Gets the RemoveItemCommand property. /// TODO Update documentation: /// Changes to that property's value raise the PropertyChanged event. /// This property's value is broadcasted by the Messenger's default instance when it changes. /// </summary> public RelayCommand<string> RemoveItemCommand { get { return _removeItemCommand; } set { if (_removeItemCommand == value) { return; } var oldValue = _removeItemCommand; _removeItemCommand = value; // Update bindings, no broadcast RaisePropertyChanged(RemoveItemCommandPropertyName); } } /// <summary> /// The <see cref="AddItemCommand" /> property's name. /// </summary> public const string AddItemCommandPropertyName = "AddItemCommand"; private RelayCommand<string> _addItemCommand = null; /// <summary> /// Gets the AddItemCommand property. /// TODO Update documentation: /// Changes to that property's value raise the PropertyChanged event. /// This property's value is broadcasted by the Messenger's default instance when it changes. /// </summary> public RelayCommand<string> AddItemCommand { get { return _addItemCommand; } set { if (_addItemCommand == value) { return; } var oldValue = _addItemCommand; _addItemCommand = value; // Update bindings, no broadcast RaisePropertyChanged(AddItemCommandPropertyName); } } /// <summary> /// Initializes a new instance of the StringListViewModel class. /// </summary> public StringListViewModel(string sectionName, string label) : base(sectionName, label) { ObservableValue = new ObservableCollection<string>(Value); AddItemCommand = new RelayCommand<string>(param => { if (param != string.Empty) { Value.Add(param); ObservableValue.Add(param); } }); RemoveItemCommand = new RelayCommand<string>(param => { if (param != null) { Value.Remove(param); ObservableValue.Remove(param); } }); } } As you can see in the constructor, I currently have "Value" mirrored into a new ObservableCollection called "ObservableValue", which is then bound to by a ListView in the XAML. It works well this way, but cloning the List seems like such a hacky way to do this. While bound to Value, I've tried adding: RaisePropertyChanged("Value"); to the AddItemCommand and RemoveItemCommand, but this doesn't work, the ListView won't get updated. What is the proper way to do this?

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  • Navigation in a #WP7 application with MVVM Light

    - by Laurent Bugnion
    In MVVM applications, it can be a bit of a challenge to send instructions to the view (for example a page) from a viewmodel. Thankfully, we have good tools at our disposal to help with that. In his excellent series “MVVM Light Toolkit soup to nuts”, Jesse Liberty proposes one approach using the MVVM Light messaging infrastructure. While this works fine, I would like to show here another approach using what I call a “view service”, i.e. an abstracted service that is invoked from the viewmodel, and implemented on the view. Multiple kinds of view services In fact, I use view services quite often, and even started standardizing them for the Windows Phone 7 applications I work on. If there is interest, I will be happy to show other such view services, for example Animation services, responsible to start/stop animations on the view. Dialog service, in charge of displaying messages to the user and gathering feedback. Navigation service, in charge of navigating to a given page directly from the viewmodel. In this article, I will concentrate on the navigation service. The INavigationService interface In most WP7 apps, the navigation service is used in quite a straightforward way. We want to: Navigate to a given URI. Go back. Be notified when a navigation is taking place, and be able to cancel. The INavigationService interface is quite simple indeed: public interface INavigationService { event NavigatingCancelEventHandler Navigating; void NavigateTo(Uri pageUri); void GoBack(); } Obviously, this interface can be extended if necessary, but in most of the apps I worked on, I found that this covers my needs. The NavigationService class It is possible to nicely pack the navigation service into its own class. To do this, we need to remember that all the PhoneApplicationPage instances use the same instance of the navigation service, exposed through their NavigationService property. In fact, in a WP7 application, it is the main frame (RootFrame, of type PhoneApplicationFrame) that is responsible for this task. So, our implementation of the NavigationService class can leverage this. First the class will grab the PhoneApplicationFrame and store a reference to it. Also, it registers a handler for the Navigating event, and forwards the event to the listening viewmodels (if any). Then, the NavigateTo and the GoBack methods are implemented. They are quite simple, because they are in fact just a gateway to the PhoneApplicationFrame. The whole class is as follows: public class NavigationService : INavigationService { private PhoneApplicationFrame _mainFrame; public event NavigatingCancelEventHandler Navigating; public void NavigateTo(Uri pageUri) { if (EnsureMainFrame()) { _mainFrame.Navigate(pageUri); } } public void GoBack() { if (EnsureMainFrame() && _mainFrame.CanGoBack) { _mainFrame.GoBack(); } } private bool EnsureMainFrame() { if (_mainFrame != null) { return true; } _mainFrame = Application.Current.RootVisual as PhoneApplicationFrame; if (_mainFrame != null) { // Could be null if the app runs inside a design tool _mainFrame.Navigating += (s, e) => { if (Navigating != null) { Navigating(s, e); } }; return true; } return false; } } Exposing URIs I find that it is a good practice to expose each page’s URI as a constant. In MVVM Light applications, a good place to do that is the ViewModelLocator, which already acts like a central point of setup for the views and their viewmodels. Note that in some cases, it is necessary to expose the URL as a string, for instance when a query string needs to be passed to the view. So for example we could have: public static readonly Uri MainPageUri = new Uri("/MainPage.xaml", UriKind.Relative); public const string AnotherPageUrl = "/AnotherPage.xaml?param1={0}&param2={1}"; Creating and using the NavigationService Normally, we only need one instance of the NavigationService class. In cases where you use an IOC container, it is easy to simply register a singleton instance. For example, I am using a modified version of a super simple IOC container, and so I can register the navigation service as follows: SimpleIoc.Register<INavigationService, NavigationService>(); Then, it can be resolved where needed with: SimpleIoc.Resolve<INavigationService>(); Or (more frequently), I simply declare a parameter on the viewmodel constructor of type INavigationService and let the IOC container do its magic and inject the instance of the NavigationService when the viewmodel is created. On supported platforms (for example Silverlight 4), it is also possible to use MEF. Or, of course, we can simply instantiate the NavigationService in the ViewModelLocator, and pass this instance as a parameter of the viewmodels’ constructor, injected as a property, etc… Once the instance has been passed to the viewmodel, it can be used, for example with: NavigationService.NavigateTo(ViewModelLocator.ComparisonPageUri); Testing Thanks to the INavigationService interface, navigation can be mocked and tested when the viewmodel is put under unit test. Simply implement and inject a mock class, and assert that the methods are called as they should by the viewmodel. Conclusion As usual, there are multiple ways to code a solution answering your needs. I find that view services are a really neat way to delegate view-specific responsibilities such as animation, dialogs and of course navigation to other classes through an abstracted interface. In some cases, such as the NavigationService class exposed here, it is even possible to standardize the implementation and pack it in a class library for reuse. I hope that this sample is useful! Happy coding. Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • What comes first in Ruby's object model?

    - by Timothy
    I've been reading Metaprogramming Ruby and the object model like the chicken or egg dilemma. In Ruby 1.8, the Object class is an instance of Class. Module's superclass is Object and is an instance of Class. Class' superclass is Module, and it is an instance of Class (self-referential). Say class SomeClass; end is defined somewhere; SomeClass is an instance of Class, however its superclass is Object. Why does an instance of Class have Object as the superclass instead of nil? Also, if Object is to exist, then Class has to exist, but then Module has to exist, but for Module to exist Object has to exist. How are these classes created?

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