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  • How to check for C++ copy ellision

    - by Steve
    I ran across this article on copy ellision in C++ and I've seen comments about it in the boost library. This is appealing, as I prefer my functions to look like verylargereturntype DoSomething(...) rather than void DoSomething(..., verylargereturntype& retval) So, I have two questions about this Google has virtually no documentation on this at all, how real is this? How can I check that this optimization is actually occuring? I assume it involves looking at the assembly, but lets just say that isn't my strong suit. If anyone can give a very basic example as to what successful ellision looks like, that would be very useful I won't be using copy ellision just to prettify things, but if I can be guaranteed that it works, it sounds pretty useful.

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  • Can VBScript determine the most recently modified (or added) file in a particular folder?

    - by Jimminy
    Hello, I have a script (or more accurately WILL have a script) that checks a folder and copies a file from this folder to a different location (will run once per day). The fileName that I'd like to copy from, however, changes based on the date. Basically, instead of setting the "strFilePath" to "C:\somePath\somePath2\myFile.txt" I would like to simply take the most recently modified (or added - does this make a difference in terms of the script??) in the "somePath2" folder and copy it to the destination. Bonus (but not completely necessary) would be to check in the script if the file was modified/added in the last 24 hours and only copy it over in that case. Thanks for your help!

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  • Problem with pointer copy in C

    - by Stefano Salati
    I radically re-edited the question to explain better my application, as the xample I made up wasn't correct in many ways as you pointed out: I have one pointer to char and I want to copy it to another pointer and then add a NULL character at the end (in my real application, the first string is a const, so I cannot jsut modify it, that's why I need to copy it). I have this function, "MLSLSerialWriteBurst" which I have to fill with some code adapt to my microcontroller. tMLError MLSLSerialWriteBurst( unsigned char slaveAddr, unsigned char registerAddr, unsigned short length, const unsigned char *data ) { unsigned char *tmp_data; tmp_data = data; *(tmp_data+length) = NULL; // this function takes a tmp_data which is a char* terminated with a NULL character ('\0') if(EEPageWrite2(slaveAddr,registerAddr,tmp_data)==0) return ML_SUCCESS; else return ML_ERROR; } I see there's a problem here: tha fact that I do not initialize tmp_data, but I cannot know it's length.

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  • How to return a copy of the data in C++

    - by Josh Curren
    I am trying to return a new copy of the data in a C++ Template class. The following code is getting this error: invalid conversion from ‘int*’ to ‘int’. If I remove the new T then I am not returning a copy of the data but a pointer to it. template<class T> T OrderedList<T>::get( int k ) { Node<T>* n = list; for( int i = 0; i < k; i++ ) { n=n->get_link(); } return new T( n->get_data() ); // This line is getting the error ********** }

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  • How use AppEngine's Datastore Admin: Copy to Another App Feature

    - by Nick Siderakis
    I recently enabled AppEngine's Datastore Admin. I do not understand the instructions on how to copy my data to another app. Note: The target application must enable remote_api and must include this application’s ID in its HTTP_X_APPENGINE_INBOUND_APPID list. WARNING This application’s data is writable. We can only guarantee a consistent copy when the data being copied is read-only. Note: Blobs (binary data) will not be copied. To enable the remote_api I included the following in the app.yaml: builtins: - remote_api: on I have no idea what HTTP_X_APPENGINE_INBOUND_APPID is, and a Google search yields no results....any ideas?

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  • Copy one object to another

    - by developer
    Hi All, I have 2 tables, user and userprofile. The userprofile table has a lot of fields similar to the user table. What I need to do is, on click of a button I need to copy all the fields of user table to userprofile table. UserModel AttData = UserModel[0]; DataServices.Save((UserProfile)AttData.ProfileModel.Instance); UserModel[0] contains all the data in user table. I want to copy this data to AttData.ProfileModel.Instance. How can I do that?

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  • How to code the set method of a Map with another Map as value?

    - by Nazgulled
    I normally do this to set a new Map to a private variable: public static void setListaClausulas(Map<String, Clausula> nvLista) { listaClausulas = new TreeMap<String, Clausula>(nvLista); } I suppose this is ok to set a new copy of the nvLista and all it's members and not a reference, is it? But now I have a Map inside another Map and I'm doing this: public static void setListaClausulas(Map<String, Map<String, Clausula>> nvLista) { listaClausulas = new TreeMap<String, Map<String, Clausula>>(nvLista); } Is this the correct way to do it or do you recommend something else? What I want is to set a new copy of nvLista (and all it's elements) and not copy just the reference.

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  • Requring static class setter to be called before constructor, bad design?

    - by roverred
    I have a class, say Foo, and every instance of Foo will need and contain the same List object, myList. Since every class instance will share the same List Object, I thought it would be good to make myList static and use a static function to set myList before the constructor is called. I was wondering if this was bad, because this requires the setter to be called before the constructor? If the person doesn't, the program will crash. Alternative way would be passing myList every time.

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  • Why `A & a = a` is valid?

    - by psaghelyi
    #include <iostream> #include <assert.h> using namespace std; struct Base { Base() : m_member1(1) {} Base(const Base & other) { assert(this != &other); // this should trigger m_member1 = other.m_member1; } int m_member1; }; struct Derived { Derived(Base & base) : m_base(m_base) {} // m_base(base) Base & m_base; }; void main() { Base base; Derived derived(base); cout << derived.m_base.m_member1 << endl; // crashes here } The above example is a synthesized version of a mistyped constructor. I used reference at the class member Derived::m_base because I wanted to make sure that the member will be initialized as the constructor had called. One problem is that nor GCC nor MSVC gives me a warning at m_base(m_base). But the more serious for me is that the assert finds everything fine and the application crashes later (sometimes far away from the mistake). Question: Is there any way to indicate such mistakes?

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  • get and set for class in model - MVC 2 asp.net

    - by bergin
    Hi there, I want to improve the program so it has a proper constructor but also works with the models environment of MVC. I currently have: public void recordDocument(int order_id, string filename, string physical_path, string slug, int bytes) { ArchiveDocument doc = new ArchiveDocument(); doc.order_id = order_id; doc.filename = filename; doc.physical_path = physical_path; doc.slug = slug; doc.bytes = bytes; db.ArchiveDocuments.InsertOnSubmit(doc); } This obviously should be a constructor and should change to the leaner: public void recordDocument(ArchiveDocument doc) { db.ArchiveDocuments.InsertOnSubmit(doc); } with a get & set somewhere else - not sure of the syntax - do I create a partial class? so: creating in the somewhere repository - ArchiveDocument doc = new ArchiveDocument(order_id, idTaggedFilename, physical_path, slug, bytes); and then: namespace ordering.Models { public partial class ArchiveDocument { int order_id, string filename, string physical_path, string slug, int bytes; public archiveDocument(int order_id, string filename, string physical_path, string slug, int bytes){ this.order_id = order_id; etc } } How should I alter the code?

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  • Java: using generic wildcards with subclassing

    - by gibberish
    Say I have a class Foo, a class A and some subclass B of A. Foo accepts A and its sublclasses as the generic type. A and B both require a Foo instance in their constructor. I want A's Foo to be of type A , and B's Foo to be of type B or a superclass of B. So in effect, So I only want this: Foo<X> bar = new Foo<X>; new B(bar); to be possible if X is either A, B, or a both subclass of A and superclass of B. So far this is what I have: class Foo<? extends A>{ //construct } class A(Foo<A> bar){ //construct } class B(Foo<? super B> bar){ super(bar); //construct } The call to super(...) doesn't work, because <A> is stricter than <? super B>. Is it somehow possible to use the constructor (or avoid code duplication by another means) while enforcing these types? Edit: Foo keeps a collection of elements of the generic parameter type, and these elements and Foo have a bidirectional link. It should therefore not be possible to link an A to a Foo.

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  • C++: Construction and initialization order guarantees

    - by Helltone
    Hi, I have some doubts about construction and initialization order guarantees in C++. For instance, the following code has four classes X, Y, Z and W. The main function instantiates an object of class X. X contains an object of class Y, and derives from class Z, so both constructors will be called. Additionally, the const char* parameter passed to X's constructor will be implicitly converted to W, so W's constructor must also be called. What are the guarantees the C++ standard gives on the order of the calls to the copy constructors? Or, equivalently, this program is allowed to print? #include <iostream> class Z { public: Z() { std::cout << "Z" << std::endl; } }; class Y { public: Y() { std::cout << "Y" << std::endl; } }; class W { public: W(const char*) { std::cout << "W" << std::endl; } }; class X : public Z { public: X(const W&) { std::cout << "X" << std::endl; } private: Y y; }; int main(int, char*[]) { X x("x"); return 0; }

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  • Why would one want to use the public constructors on Boolean and similar immutable classes?

    - by Robert J. Walker
    (For the purposes of this question, let us assume that one is intentionally not using auto(un)boxing, either because one is writing pre-Java 1.5 code, or because one feels that autounboxing makes it too easy to create NullPointerExceptions.) Take Boolean, for example. The documentation for the Boolean(boolean) constructor says: Note: It is rarely appropriate to use this constructor. Unless a new instance is required, the static factory valueOf(boolean) is generally a better choice. It is likely to yield significantly better space and time performance. My question is, why would you ever want to get a new instance in the first place? It seems like things would be simpler if constructors like that were private. For example, if they were, you could write this with no danger (even if myBoolean were null): if (myBoolean == Boolean.TRUE) It'd be safe because all true Booleans would be references to Boolean.TRUE and all false Booleans would be references to Boolean.FALSE. But because the constructors are public, someone may have used them, which means that you have to write this instead: if (Boolean.TRUE.equals(myBoolean)) But where it really gets bad is when you want to check two Booleans for equality. Something like this: if (myBooleanA == myBooleanB) ...becomes this: if ( (myBooleanA == null && myBooleanB == null) || (myBooleanA == null && myBooleanA.equals(myBooleanB)) ) I can't think of any reason to have separate instances of these objects which is more compelling than not having to do the nonsense above. What say you?

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  • Different behavior of functors (copies, assignments) in VS2010 (compared with VS2005)

    - by Patrick
    When moving from VS2005 to VS2010 we noticed a performance decrease, which seemed to be caused by additional copies of a functor. The following code illustrates the problem. It is essential to have a map where the value itself is a set. On both the map and the set we defined a comparison functor (which is templated in the example). #include <iostream> #include <map> #include <set> class A { public: A(int i, char c) : m_i(i), m_c(c) { std::cout << "Construct object " << m_c << m_i << std::endl; } A(const A &a) : m_i(a.m_i), m_c(a.m_c) { std::cout << "Copy object " << m_c << m_i << std::endl; } ~A() { std::cout << "Destruct object " << m_c << m_i << std::endl; } void operator= (const A &a) { m_i = a.m_i; m_c = a.m_c; std::cout << "Assign object " << m_c << m_i << std::endl; } int m_i; char m_c; }; class B : public A { public: B(int i) : A(i, 'B') { } static const char s_c = 'B'; }; class C : public A { public: C(int i) : A(i, 'C') { } static const char s_c = 'C'; }; template <class X> class compareA { public: compareA() : m_i(999) { std::cout << "Construct functor " << X::s_c << m_i << std::endl; } compareA(const compareA &a) : m_i(a.m_i) { std::cout << "Copy functor " << X::s_c << m_i << std::endl; } ~compareA() { std::cout << "Destruct functor " << X::s_c << m_i << std::endl; } void operator= (const compareA &a) { m_i = a.m_i; std::cout << "Assign functor " << X::s_c << m_i << std::endl; } bool operator() (const X &x1, const X &x2) const { std::cout << "Comparing object " << x1.m_i << " with " << x2.m_i << std::endl; return x1.m_i < x2.m_i; } private: int m_i; }; typedef std::set<C, compareA<C> > SetTest; typedef std::map<B, SetTest, compareA<B> > MapTest; int main() { int i = 0; std::cout << "--- " << i++ << std::endl; MapTest mapTest; std::cout << "--- " << i++ << std::endl; SetTest &setTest = mapTest[0]; std::cout << "--- " << i++ << std::endl; } If I compile this code with VS2005 I get the following output: --- 0 Construct functor B999 Copy functor B999 Copy functor B999 Destruct functor B999 Destruct functor B999 --- 1 Construct object B0 Construct functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Copy object B0 Copy functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Copy object B0 Copy functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Destruct functor C999 Destruct object B0 Destruct functor C999 Destruct object B0 --- 2 If I compile this with VS2010, I get the following output: --- 0 Construct functor B999 Copy functor B999 Copy functor B999 Destruct functor B999 Destruct functor B999 --- 1 Construct object B0 Construct functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Copy object B0 Copy functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Copy functor C999 Assign functor C999 Assign functor C999 Destruct functor C999 Copy object B0 Copy functor C999 Copy functor C999 Copy functor C999 Destruct functor C999 Destruct functor C999 Copy functor C999 Assign functor C999 Assign functor C999 Destruct functor C999 Destruct functor C999 Destruct object B0 Destruct functor C999 Destruct object B0 --- 2 The output for the first statement (constructing the map) is identical. The output for the second statement (creating the first element in the map and getting a reference to it), is much bigger in the VS2010 case: Copy constructor of functor: 10 times vs 8 times Assignment of functor: 2 times vs. 0 times Destructor of functor: 10 times vs 8 times My questions are: Why does the STL copy a functor? Isn't it enough to construct it once for every instantiation of the set? Why is the functor constructed more in the VS2010 case than in the VS2005 case? (didn't check VS2008) And why is it assigned two times in VS2010 and not in VS2005? Are there any tricks to avoid the copy of functors? I saw a similar question at http://stackoverflow.com/questions/2216041/prevent-unnecessary-copies-of-c-functor-objects but I'm not sure that's the same question. Thanks in advance, Patrick

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  • Download link for trial/evaluation copy of CA Siteminder

    - by velusbits
    Is there a trial/evaluation version available of CA Siteminder? What is CA SiteMinder? It is a centralized Internet access management system that enables user authentication and single sign-on, authentication management, policy-based authorization, identity federation and auditing of access to Web applications and portals. Where would I go for that link if one exists?

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  • Download link for trial/evaluation copy of CA Siteminder

    - by velusbits
    Is there a trial/evaluation version available of CA Siteminder? What is CA SiteMinder? It is a centralized Internet access management system that enables user authentication and single sign-on, authentication management, policy-based authorization, identity federation and auditing of access to Web applications and portals. Where would I go for that link if one exists?

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  • Copy Content from Sharepoint2007 to another Sharepoint2007

    - by Beuy
    Hi There, I have a Sharepoint 2007 web farm installation with two site collections, one is a blank site and the other is a migrated Sharepoint 2003 site collection. I want to move some specific content from the migrated 2003 collection to the 2007 collection, however I also want to change the path of where it exists, an example is that in the migrated 2003 collection HR is under Admin HR, in the 2007 collection I want HR to appear before Admin. I've looked around but haven't found a lot of information regarding how to move specific content between sites, any advice or help is greatly appreciated.

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  • Fox Pro Database File Locked by Shadow Copy?

    - by leeand00
    I'm using Process Explorer to determine what process has a lock on a particular Fox Pro Database file in windows. It's telling me that System has a lock on it. When I go to kill the "System" process (which if you ask me doesn't sound like a very good idea), it asks me if I'm sure I want to kill the System process. I haven't answered yes yet. It's a company server, and I'm thinking that maybe my only option is to tell everybody to get off of it and reboot. Do I have any other options?

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  • Rackspace copy script failure message "java.net.SocketTimeoutException: Read timed out"

    - by user53864
    I am using Rackspace for Ubuntu cloud server. Everyday a script(I guess the script is from rackspace) executes on the cloud servers which copies the backfile to the Rackspace CloudFiles and sends the mail as if the files are copied and I've scheduled the script on the cloud servers. I've no much knowledge of the script and I guess the script is based on Cruise(as I could see build.xml, some jar files ...). Everyday the files are copied to the Rackspace from cloud servers but sometimes don't know why, the files will be copied to Rackspace sending an error failure message or sometimes the files will not be copied and sends the error failure message like the one below. Error while backing up on Station1 on 03/03/2011 04:50 AM and reason for error is java.net.SocketTimeoutException: Read timed out Anybody using Rackspace?, anybody has any fix for this?

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  • What usb-bootable utility should I use to copy SATA hard drives?

    - by Steve Brown
    I have a computer that only has two SATA connections and I need to copy one SATA hard drive to another. Since I have to unplug the CD drive to copy the drives I need a USB-bootable utility. I have an old school copy of Norton Ghost (CD based): Ghost has always worked well for me in the past - I see there is a new "version 15" out but I'm not sure if it is worth buying. A friend has Acronis True Image on a USB drive: We tried to use that on the computer but it was unable to copy both partitions (restore partition and main partition). Of course there may be some problem with the drive that is keeping Acronis from working (it is just exiting with a lame error about not being able to copy the disks and no error code or detailed information), but I'm interested in knowing if there is a better, more solid, or widely used solution that I should invest in. What usb-bootable utilities can I use to copy SATA hard drives?

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  • Copy Office files from a Mac to a PC

    - by Martin
    A friend of me recently dumped his Mac fpr a PC. He used Microsoft Office for Mac and has several hundred Files (Word, Excel) which were copied over to the new PC using a USB disk. Microsoft Office is now unable to read any of there files. I suspect this is because of little endian vs. big endian. Is there any tool which can converted all theses files automatically, doing this by hand would take ages.

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  • Copy Office files from a Mac to a PC

    - by Martin
    A friend of me recently dumped his Mac fpr a PC. He used Microsoft Office for Mac and has several hundred Files (Word, Excel) which were copied over to the new PC using a USB disk. Microsoft Office is now unable to read any of there files. I suspect this is because of little endian vs. big endian. Is there any tool which can converted all theses files automatically, doing this by hand would take ages.

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