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• Strategy for desugaring Haskell

  - by luqui

  I'm developing a virtual machine for purely functional programs, and I would like to be able to test and use the the wide variety of Haskell modules already available. The VM takes as input essentially terms in the untyped lambda calculus. I'm wondering what would be a good way to extract such a representation from modern Haskell modules (eg. with MPTC's, pattern guards, etc.). I did a little research and there doesn't seem to be a tool that does this already (I would be delighted to be mistaken), and that's okay. I'm looking for an approach. GHC Core seems too operationally focused, especially since one of the things the VM does is to change the evaluation order significantly. Are there any accessible intermediate representations that correspond more closely to the lambda calculus?

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• How can I read out internal pdf creation/modified date with Windows PowerShell?

  - by Martin

  PDF files seem to have a separate set of file properties which contain (among others) a creation date and a modified date (see screenshot here: http://ventajamarketing.com/writingblog/wp-content/uploads/2012/02/Acrobat-Document-Properties1-300x297.png). Those date obviously can differ from the creation and modified date shown in the file system (Windows Explorer). How can I access the date information in the PDF file and read it out in Windows 7 with Windows PowerShell (or maybe another method)?

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• C++ Multiple Inheritance Question

  - by John

  The scenario generating this is quite complex so I'll strip out a few pieces and give an accurate representation of the classes involved. /* This is inherited using SI by many classes, as normal */ class IBase { virtual string toString()=0; }; /* Base2 can't inherit IBase due to other methods on IBase which aren't appropriate */ class Base2 { string toString() { ... } }; /* a special class, is this valid? */ class Class1 : public IBase, public Base2 { }; So, is this valid? Will there be conflicts on the toString? Or can Class1 use Base2::toString to satisfy IBase? Like I say there are lots of other things not shown, so suggestions for major design changes on this example are probably not that helpful... though any general suggestions/advice are welcome.

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• OpenGL embedded in gtk has colour badly displayed

  - by Sardathrion

  Note that this is a re-write now that I have more clues as to where the problem could be... I am creating a GTK GUI which contains two embedded OpenGL displays. Both use the same shader code (complied once for each). On my normal hardware, this works fine. On a virtual machine running on the same hardware, I get horrible colours -- see images. I suspect that the shader code is at fault -- certainly dropping a simpler shader does make the problem moot. However, I do need both diffuse and spot lights in my shader thus making it non-trivial. Anyone has seen this before?

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• java cannot reserver heap size error on windows server

  - by Prad

  HI, I have the following configuration: Server : windows 2003 server (32 bit) java version: 1.5_0_22 I get the following error when executing from command line ( my code is based off eclipse wihch gives the same error) java -XX:MaxPermSize=256m -Xmx512m Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine. The server has over 20GB physical memory with over 19 GB free right now. It does not give an error upto -Xmx486m I have read other articles about contiguous memory space. There is hardly anything running on this server. Can I validae this in any way? Thanks

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• How can I retrieve cookies for webserver A when my project is deployed on webserver B?

  - by medopal

  The project is multiple modules, each of them is deployed to a separate webserver. All of them on the same mainframe. (same IP address) I have a main menu where I login and then list all the available modules on all servers. From here I can click and go to any of them modules. I send cookies in the response (when logging in, say Server A), then on Server B (one of the modules) when I want to go back to the main menu, I check the cookies to see if the user is logged in. The problem is, Server B isn't seeing cookies generated by Server A. So each time I return to main menu, the user will be logged out. Is there anyway to store cookies to be used by multiple virtual webservers (on same IP) or any other idea?

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• OpenSSH (Windows) does not forward X11

  - by Shulhi Sapli

  I'm running Ubuntu 13.04 in VM and I wanted to do X11 forwarding to my host (Win 8), so far it works fine using PuTTY and XMing server for Windows. But I am curious why it doesn't work if I use OpenSSH binaries (it comes together with Git for windows). This is what I've done so far: ssh -X [email protected] (also tried with -Y) then gedit but received error of Cannot open display. echo $DISPLAY came out as empty. So, I try to export DISPLAY=localhost:0.0 but it still won't work. The DISPLAY environment that I set is exactly as when it runs with Putty. I also try changing the DISPLAY to 192.168.2.3:0.0 and other display number as well, but still it won't work. Of course I could just use Putty to make it work, but I was wondering why OpenSSH binaries does not work. I have enabled all settings required in both /etc/ssh/ssh_config and /etc/ssh/sshd_config. If I run with -v option, this is what I get F:\SkyDrive\Projects> ssh -X -v [email protected] OpenSSH_4.6p1, OpenSSL 0.9.8e 23 Feb 2007 debug1: Connecting to 192.168.2.3 [192.168.2.3] port 22. debug1: Connection established. debug1: identity file /c/Users/Shulhi/.ssh/identity type -1 debug1: identity file /c/Users/Shulhi/.ssh/id_rsa type -1 debug1: identity file /c/Users/Shulhi/.ssh/id_dsa type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_6.1p1 Debian-4 debug1: match: OpenSSH_6.1p1 Debian-4 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_4.6 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-cbc hmac-md5 none debug1: kex: client->server aes128-cbc hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Host '192.168.2.3' is known and matches the RSA host key. debug1: Found key in /c/Users/Shulhi/.ssh/known_hosts:2 debug1: ssh_rsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,password debug1: Next authentication method: publickey debug1: Trying private key: /c/Users/Shulhi/.ssh/identity debug1: Trying private key: /c/Users/Shulhi/.ssh/id_rsa debug1: Next authentication method: password [email protected]'s password: It seems that there is no request for X11 (I'm not sure if there is should be one too here). Any pointers why it doesn't work?

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• Does C++ have a proper implementation of interface that does not use vtable?

  - by gilbertc

  Does C++ have a proper implementation of interface that does not use vtable? for example class BaseInterface{ public: virtual void func() const = 0; } class BaseInterfaceImpl:public BaseInterface{ public: void func(){ std::cout<<"called."<<endl; } } BaseInterface* obj = new BaseInterfaceImpl(); obj->func(); the call to func at the last line goes to vtable to find the func ptr of BaseInterfaceImpl::func, but is there any C++ way to do that directly as the BaseInterfaceImpl is not subclassed from any other class besides the pure interface class BaseInterface? Thanks. Gil.

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• Copy open files over network

  - by redknight

  Copy open files over network- I have a situation where I ahve to copy the entire contents of a user's hard disk over the remotely over the local network and silently. I am concerned about open files the user might have. Is there a free software or method that I can use to be able to copy the hard disk of the user?

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• Why are C, C++, and LISP so prevalent in embedded devices and robots?

  - by David

  It seems that the software language skills most sought for embedded devices and robots are C, C++, and LISP. Why haven't more recent languages made inroads into these applications? For example, Erlang would seem particularly well-suited to robotic applications, since it makes concurrent programming easier and allows hot swapping of code. Python would seem to be useful, if for no other reason than its support of multiple programming paradigms. I'm even surprised that Java hasn't made a foray into general robotic programming. I'm sure one argument would be, "Some newer languages are interpreted, not compiled" - implying that compiled languages are quicker and use fewer computational resources. Is this still the case, in a time when we can put a Java Virtual Machine on a cell phone or a SunSpot? (and isn't LISP interpreted anyway?)

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• .htaccess: subdomain to sub-folder

  - by Oden

  Hey, How can i redirect a subdomain call to a folder? So when the site, sub.domain.com is requested, the name of the subdomain should point to a subfolder. The server is configured to add every request to the domain, but i get a 404 page everytime i do a non-defined subdomain call (witch is trivial, because theres nothing defined) EDIT my request looks like this: sub.domain.com What and i want to get that it works like a "virtual subdomain", because it has to request a folder with the same name that the subdomain. (domain.com/sub/) So the question is: How to solve this, with .htaccess?

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• Is it possible to configure Apache to host both an ASP.NET Web Service and a PHP Web site?

  - by Eduardo León

  Noob question (because I'm a noob when it comes to Web development). I'm not sure whether I should ask it here or at ServerFault. I am developing an ASP.NET Web Service and a PHP Web site consuming the Web Service. They are meant to be run on different machines. However, only for development purposes, I need to run both on my machine. I cannot use virtual machines. I would like to know if it is possible to configure IIS Apache to host both my Web Service and my Web site? Or, do I need to host the PHP site using Apache? I am using IIS 7.5 Apache HTTP Server 2.2 (NOTE: I have nothing against Apache. In fact, so far I like it more than IIS, however, I would rather not have two Web server applications installed in the same machine.) PHP 5.3.4 .NET Framework 2.0 3.0 or 3.5 (whichever comes with Visual Studio 2008) mod_aspdotnet for Apache 2.2

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• Looking for Hard Drive Health Monitoring software

  - by RandyMorris

  I am aware that the current standard method of drive redundancy and backups would be a better solution, but I would be interested if there was a software that could be installed on workstation computers that could monitor hard drive health and give a warning if the drive looks like a failure is imminent. I have tried hdd health but it does not give me very useful information. I am not interested in drive space, just want a heads up before a drive failure. Anyone know anything like this?

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• What's the best way to implement a dynamic proxy in C#?

  - by gap

  Hi, I've got a need to create a dynamic proxy in C#. I want this class to wrap another class, and take on it's public interface, forwarding calls for those functions: class MyRootClass { public virtual void Foo() { Console.Out.WriteLine("Foo!"); } } interface ISecondaryInterface { void Bar(); } class Wrapper<T> : ISecondaryInterface where T: MyRootClass { public Wrapper(T otherObj) { } public void Bar() { Console.Out.WriteLine("Bar!"); } } Here's how I want to use it: Wrapper<MyRootClass> wrappedObj = new Wrapper<MyRootClass>(new MyRootClass()); wrappedObj.Bar(); wrappedObj.Foo(); to produce: Bar! Foo! Any ideas? What's the easiest way to do this? What's the best way to do this? Thanks so much.

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• class which cannot be derived

  - by benjamin button

  I found this code here class Usable; class Usable_lock { friend class Usable; private: Usable_lock() {} Usable_lock(const Usable_lock&) {} }; class Usable : public virtual Usable_lock { // ... public: Usable(); Usable(char*); // ... }; Usable a; class DD : public Usable { }; DD dd; // error: DD::DD() cannot access // Usable_lock::Usable_lock(): private member Could anybody explain me this code?

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• Where does the compiler store methods for C++ classes?

  - by Mashmagar

  This is more a curiosity than anything else... Suppose I have a C++ class Kitty as follows: class Kitty { void Meow() { //Do stuff } } Does the compiler place the code for Meow() in every instance of Kitty? Obviously repeating the same code everywhere requires more memory. But on the other hand, branching to a relative location in nearby memory requires fewer assembly instructions than branching to an absolute location in memory on modern processors, so this is potentially faster. I suppose this is an implementation detail, so different compilers may perform differently. Keep in mind, I'm not considering static or virtual methods here.

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• Handler not yet determined error

  - by SourceC

  Hello, I don’t know anything about deploying a website, so I probably made some stupid mistake. Anyways, I opened IIS 7 manager, created new virtual directory ( via Add Application ) and pointed it to physical directory where Visual studio saved my Web project. But when I tried to request an .aspx page, browser reported the following error (I won’t post the whole error, but just the interesting bits): Handler: Not yet determined Config Error: Cannot read configuration file due to insufficient permissions Logon User: Not yet determined A) why is handler not yet determined? As far as I know, IIS7 does have Asp.Net handler registered?! B) Why wouldn’t IIS have sufficient permissions? Does that mean I should give IIS higher privileges? Or does Asp.Net runtime have insufficient permissions? C) Could the error also be due to the fact that perhaps it expected the user to authenticate itself? I’m assuming this due to Logon user not yet being determined? D) And finally, any ideas how to make it work? thanx

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• c++ polymorphism and other function question

  - by aharont

  i have got this code: class father{ public: virtual void f() { cout<<1;} }; class son:public father{ public: void f() {cout<<2;} }; void test (father x){x.f();} int main(){ son s; test(s); } the question says: the output is '1', what is the rule about polymorphism that the programmer forgot and how can i fix it so the output would be '2'? there is another rule that the programmer forgot when he wrote the father class, and he need to add an empty function to avoid problems from other sons of the father class. what is the rule and what is the missing function? another question write the g function so the next code would run with no crashes int x=11; g(x)=22;

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• How can I mount a VMWare Disk in Windows 7 64-Bit

  - by Unkwntech

  I need to mount a VMWare disk image in Windows 7 64-Bit however the "VMware Mount Utility" only works on 32-Bit operating systems. Is there an application or method that I can use to mount the disk?

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• How to set -Xbootclasspath for a JRE with a custom launcher?

  - by Tom

  I have a Java application which is using a certain Java Runtime Environment. The application uses it's own launcher to startup the java virtual machine. No use of the java.exe, javaw.exe, javaws.exe binaries is being made -- as the application seems to have it's own launcher which is a different executable. This custom launcher is using the rest of the JRE files, such as bin/client/jvm.dll and rt.jar package etc. Now, the problem is that I want to set a boot class path for this custom launcher. The custom launcher does not support the -Xbootclasspath command line parameter, like the default java.exe does. Is there any way for me to set the boot class path now for this java runtime environment? Thanks in advance. Some things to keep in mind: I do not have the source of this application This is meant for self and personal debugging use only, not for distribution

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• C++ Array of pointers: delete or delete []?

  - by Jasper

  Cosider the following code: class Foo { Monster* monsters[6]; Foo() { for (int i = 0; i < 6; i++) { monsters[i] = new Monster(); } } virtual ~Foo(); } What is the correct destructor? this: Foo::~Foo() { delete [] monsters; } or this: Foo::~Foo() { for (int i = 0; i < 6; i++) { delete monsters[i]; } } I currently have the uppermost constructor and everything is working okey, but of course I cannot see if it happens to be leaking... Personally, I think the second version is much more logical considering what I am doing. Anyway, what is the "proper" way to do this?

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• Android Video Camera : still picture

  - by Alex

  I use the camera intent to capture video. Here is the problem: If I use this line of code, I can record video. But onActivityResult doesn't work. Intent intent = new Intent("android.media.action.VIDEO_CAMERA"); If I use this line of code, after press the recording button, the camera is freezed, I mean, the picture is still. Intent intent = new Intent(MediaStore.ACTION_VIDEO_CAPTURE); BTW, when I use $Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); to capture a picture, it works fine. The java file is as follows: package com.camera.picture; import java.io.File; import java.text.SimpleDateFormat; import java.util.Date; import android.app.Activity; import android.content.ContentValues; import android.content.Intent; import android.net.Uri; import android.os.Bundle; import android.os.Environment; import android.provider.MediaStore; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.ImageView; import android.widget.Toast; import android.widget.VideoView; public class PictureCameraActivity extends Activity { private static final int IMAGE_CAPTURE = 0; private static final int VIDEO_CAPTURE = 1; private Button startBtn; private Button videoBtn; private Uri imageUri; private Uri videoUri; private ImageView imageView; private VideoView videoView; /** Called when the activity is first created. * sets the content and gets the references to * the basic widgets on the screen like * {@code Button} or {@link ImageView} */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); imageView = (ImageView)findViewById(R.id.img); videoView = (VideoView)findViewById(R.id.videoView); startBtn = (Button) findViewById(R.id.startBtn); startBtn.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { startCamera(); } }); videoBtn = (Button) findViewById(R.id.videoBtn); videoBtn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub startVideoCamera(); } }); } public void startCamera() { Log.d("ANDRO_CAMERA", "Starting camera on the phone..."); String fileName = "testphoto.jpg"; ContentValues values = new ContentValues(); values.put(MediaStore.Images.Media.TITLE, fileName); values.put(MediaStore.Images.Media.DESCRIPTION, "Image capture by camera"); values.put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg"); imageUri = getContentResolver().insert( MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values); Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri); intent.putExtra(MediaStore.EXTRA_VIDEO_QUALITY, 1); startActivityForResult(intent, IMAGE_CAPTURE); } protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == IMAGE_CAPTURE) { if (resultCode == RESULT_OK){ Log.d("ANDROID_CAMERA","Picture taken!!!"); imageView.setImageURI(imageUri); } } if (requestCode == VIDEO_CAPTURE) { if (resultCode == RESULT_OK) { Log.d("ANDROID_CAMERA","Video taken!!!"); Toast.makeText(this, "Video saved to:\n" + data.getData(), Toast.LENGTH_LONG).show(); videoView.setVideoURI(videoUri); } } } private void startVideoCamera() { // TODO Auto-generated method stub //create new Intent Log.d("ANDRO_CAMERA", "Starting camera on the phone..."); String fileName = "testvideo.mp4"; ContentValues values = new ContentValues(); values.put(MediaStore.Video.Media.TITLE, fileName); values.put(MediaStore.Video.Media.DESCRIPTION, "Video captured by camera"); values.put(MediaStore.Video.Media.MIME_TYPE, "video/mp4"); videoUri = getContentResolver().insert( MediaStore.Video.Media.EXTERNAL_CONTENT_URI, values); Intent intent = new Intent("android.media.action.VIDEO_CAMERA"); //Intent intent = new Intent(MediaStore.ACTION_VIDEO_CAPTURE); intent.putExtra(MediaStore.EXTRA_OUTPUT, videoUri); intent.putExtra(MediaStore.EXTRA_VIDEO_QUALITY, 1); // start the Video Capture Intent startActivityForResult(intent, VIDEO_CAPTURE); } private static File getOutputMediaFile() { // TODO Auto-generated method stub // To be safe, you should check that the SDCard is mounted // using Environment.getExternalStorageState() before doing this. File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory( Environment.DIRECTORY_PICTURES), "MyCameraApp"); // This location works best if you want the created images to be shared // between applications and persist after your app has been uninstalled. // Create the storage directory if it does not exist if (! mediaStorageDir.exists()){ if (! mediaStorageDir.mkdirs()){ Log.d("MyCameraApp", "failed to create directory"); return null; } } // Create a media file name String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date()); File mediaFile; mediaFile = new File(mediaStorageDir.getPath() + File.separator + "VID_"+ timeStamp + ".mp4"); return mediaFile; } /** Create a file Uri for saving an image or video */ private static Uri getOutputMediaFileUri(){ return Uri.fromFile(getOutputMediaFile()); } }

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• Why isn't passwordless ssh working?

  - by Nelson

  I have two Ubuntu Server machines sitting at home. One is 192.168.1.15 (we'll call this 15), and the other is 192.168.1.25 (we'll call this 25). For some reason, when I want to setup passwordless login from 15 to 25, it works like a champ. When I repeat the steps on 25, so that 25 can login without a password on 15, no dice. I have checked both sshd_config files. Both have: RSAAuthentication yes PubkeyAuthentication yes I have checked permissions on both servers: drwx------ 2 bion2 bion2 4096 Dec 4 12:51 .ssh -rw------- 1 bion2 bion2 398 Dec 4 13:10 authorized_keys On 25. drwx------ 2 shimdidly shimdidly 4096 Dec 4 19:15 .ssh -rw------- 1 shimdidly shimdidly 1018 Dec 4 18:54 authorized_keys On 15. I just don't understand when things would work one way and not the other. I know it's probably something obvious just staring me in the face, but for the life of me, I can't figure out what is going on. Here's what ssh -v says when I try to ssh from 25 to 15: ssh -v -p 51337 192.168.1.15 OpenSSH_5.9p1 Debian-5ubuntu1, OpenSSL 1.0.1 14 Mar 2012 debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 19: Applying options for * debug1: Connecting to 192.168.1.15 [192.168.1.15] port 51337. debug1: Connection established. debug1: identity file /home/shimdidly/.ssh/id_rsa type 1 debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048 debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048 debug1: identity file /home/shimdidly/.ssh/id_rsa-cert type -1 debug1: identity file /home/shimdidly/.ssh/id_dsa type 2 debug1: Checking blacklist file /usr/share/ssh/blacklist.DSA-1024 debug1: Checking blacklist file /etc/ssh/blacklist.DSA-1024 debug1: identity file /home/shimdidly/.ssh/id_dsa-cert type -1 debug1: identity file /home/shimdidly/.ssh/id_ecdsa type -1 debug1: identity file /home/shimdidly/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 Debian-5ubuntu1 debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr hmac-md5 none debug1: sending SSH2_MSG_KEX_ECDH_INIT debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ECDSA 54:5c:60:80:74:ab:ab:31:36:a1:d3:9b:db:31:2a:ee debug1: Host '[192.168.1.15]:51337' is known and matches the ECDSA host key. debug1: Found key in /home/shimdidly/.ssh/known_hosts:2 debug1: ssh_ecdsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,password debug1: Next authentication method: publickey debug1: Offering RSA public key: /home/shimdidly/.ssh/id_rsa debug1: Authentications that can continue: publickey,password debug1: Offering DSA public key: /home/shimdidly/.ssh/id_dsa debug1: Authentications that can continue: publickey,password debug1: Trying private key: /home/shimdidly/.ssh/id_ecdsa debug1: Next authentication method: password

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• Does C++ require a destructor call for each placement new?

  - by Josh Haberman

  I understand that placement new calls are usually matched with explicit calls to the destructor. My question is: if I have no need for a destructor (no code to put there, and no member variables that have destructors) can I safely skip the explicit destructor call? Here is my use case: I want to write C++ bindings for a C API. In the C API many objects are accessible only by pointer. Instead of creating a wrapper object that contains a single pointer (which is wasteful and semantically confusing). I want to use placement new to construct an object at the address of the C object. The C++ object will do nothing in its constructor or destructor, and its methods will do nothing but delegate to the C methods. The C++ object will contain no virtual methods. I have two parts to this question. Is there any reason why this idea will not work in practice on any production compiler? Does this technically violate the C++ language spec?

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• Why Is It That Generics Constraint Can't Be Casted to Its Derived Type?

  - by Ngu Soon Hui

  It is quite puzzling to find out that Generics Constraint Can't Be Casted to Its Derived Type. Let's say I have the following code: public abstract class BaseClass { public int Version { get { return 1; } } public string FixString { get; set; } public BaseClass() { FixString = "hello"; } public virtual int GetBaseVersion() { return Version; } } public class DeriveClass: BaseClass { public new int Version { get { return 2; } } } And guess what, this method will return a compilation error: public void FreeConversion<T>(T baseClass) { var derivedMe = (DeriveClass)baseClass; } I would have to cast the baseClass to object first before I can cast it to DerivedClass. Seems to me pretty ugly. Why this is so?

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