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  • springTestContextBeforeTestMethod failed in Maven spring-test

    - by joejax
    I try to setup a project with spring-test using TestNg in Maven. The code is like: @ContextConfiguration(locations={"test-context.xml"}) public class AppTest extends AbstractTestNGSpringContextTests { @Test public void testApp() { assert true; } } A test-context.xml simply defined a bean: <bean id="app" class="org.sonatype.mavenbook.simple.App"/> I got error for Failed to load ApplicationContext when running mvn test from command line, seems it cannot find the test-context.xml file; however, I can get it run correctly inside Eclipse (with TestNg plugin). So, test-context.xml is under src/test/resources/, how do I indicate this in the pom.xml so that 'mvn test' command will work? Thanks, UPDATE: Thanks for the reply. Cannot load context file error was caused by I moved the file arround in different location since I though the classpath was the problem. Now I found the context file seems loaded from the Maven output, but the test is failed: Running TestSuite May 25, 2010 9:55:13 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions INFO: Loading XML bean definitions from class path resource [test-context.xml] May 25, 2010 9:55:13 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh INFO: Refreshing org.springframework.context.support.GenericApplicationContext@171bbc9: display name [org.springframework.context.support.GenericApplicationContext@171bbc9]; startup date [Tue May 25 09:55:13 PDT 2010]; root of context hierarchy May 25, 2010 9:55:13 AM org.springframework.context.support.AbstractApplicationContext obtainFreshBeanFactory INFO: Bean factory for application context [org.springframework.context.support.GenericApplicationContext@171bbc9]: org.springframework.beans.factory.support.DefaultListableBeanFactory@1df8b99 May 25, 2010 9:55:13 AM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1df8b99: defining beans [app,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor]; root of factory hierarchy Tests run: 3, Failures: 2, Errors: 0, Skipped: 1, Time elapsed: 0.63 sec <<< FAILURE! Results : Failed tests: springTestContextBeforeTestMethod(org.sonatype.mavenbook.simple.AppTest) springTestContextAfterTestMethod(org.sonatype.mavenbook.simple.AppTest) Tests run: 3, Failures: 2, Errors: 0, Skipped: 1 If I use spring-test version 3.0.2.RELEASE, the error becomes: org.springframework.test.context.testng.AbstractTestNGSpringContextTests.springTestContextPrepareTestInstance() is depending on nonexistent method null Here is the structure of the project: simple |-- pom.xml `-- src |-- main | `-- java `-- test |-- java `-- resources |-- test-context.xml `-- testng.xml testng.xml: <suite name="Suite" parallel="false"> <test name="Test"> <classes> <class name="org.sonatype.mavenbook.simple.AppTest"/> </classes> </test> </suite> test-context.xml: <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd" default-lazy-init="true"> <bean id="app" class="org.sonatype.mavenbook.simple.App"/> </beans> In the pom.xml, I add testng, spring, and spring-test artifacts, and plugin: <dependency> <groupId>org.testng</groupId> <artifactId>testng</artifactId> <version>5.1</version> <classifier>jdk15</classifier> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring</artifactId> <version>2.5.6</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>2.5.6</version> <scope>test</scope> </dependency> <build> <finalName>simple</finalName> <plugins> <plugin> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.6</source> <target>1.6</target> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <suiteXmlFiles> <suiteXmlFile>src/test/resources/testng.xml</suiteXmlFile> </suiteXmlFiles> </configuration> </plugin> </plugins> Basically, I replaced 'A Simple Maven Project' Junit with TestNg, hope it works. UPDATE: I think I got the problem (still don't know why) - Whenever I extends AbstractTestNGSpringContextTests or AbstractTransactionalTestNGSpringContextTests, the test will failed with this error: Failed tests: springTestContextBeforeTestMethod(org.sonatype.mavenbook.simple.AppTest) springTestContextAfterTestMethod(org.sonatype.mavenbook.simple.AppTest) So, eventually the error went away when I override the two methods. I don't think this is the right way, didn't find much info from spring-test doc. If you know spring test framework, please shred some light on this.

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  • Class member functions instantiated by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched Stack Overflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instantiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits that are tested at runtime. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state information was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. The compiler (VC++ 2008) always complained that things didn't match. I would yell, "SFINAE, you moron!" but the moron is probably me. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice? UPDATE: Here's another try at explaining it. I want the user to be able to fill out an order (manifest) for a custom optimizer, something like ordering off of a Chinese menu - one from column A, one from column B, etc.. Waiter, from column A (updaters), I'll have the BFGS update with Cholesky-decompositon sauce. From column B (line-searchers), I'll have the cubic interpolation line-search with an eta of 0.4 and a rho of 1e-4, please. Etc... UPDATE: Okay, okay. Here's the playing-around that I've done. I offer it reluctantly, because I suspect it's a completely wrong-headed approach. It runs okay under vc++ 2008. #include <boost/utility.hpp> #include <boost/type_traits/integral_constant.hpp> namespace dj { struct CBFGS { void bar() {printf("CBFGS::bar %d\n", data);} CBFGS(): data(1234){} int data; }; template<class T> struct is_CBFGS: boost::false_type{}; template<> struct is_CBFGS<CBFGS>: boost::true_type{}; struct LMQN {LMQN(): data(54.321){} void bar() {printf("LMQN::bar %lf\n", data);} double data; }; template<class T> struct is_LMQN: boost::false_type{}; template<> struct is_LMQN<LMQN> : boost::true_type{}; struct default_optimizer_traits { typedef CBFGS update_type; }; template<class traits> class Optimizer; template<class traits> void foo(typename boost::enable_if<is_LMQN<typename traits::update_type>, Optimizer<traits> >::type& self) { printf(" LMQN %lf\n", self.data); } template<class traits> void foo(typename boost::enable_if<is_CBFGS<typename traits::update_type>, Optimizer<traits> >::type& self) { printf("CBFGS %d\n", self.data); } template<class traits = default_optimizer_traits> class Optimizer{ friend typename traits::update_type; //friend void dj::foo<traits>(typename Optimizer<traits> & self); // How? public: //void foo(void); // How??? void foo() { dj::foo<traits>(*this); } void bar() { data.bar(); } //protected: // How? typedef typename traits::update_type update_type; update_type data; }; } // namespace dj int main_() { dj::Optimizer<> opt; opt.foo(); opt.bar(); std::getchar(); return 0; }

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  • Compilation problems with vector<auto_ptr<> >

    - by petersohn
    Consider the following code: #include <iostream> #include <memory> #include <vector> using namespace std; struct A { int a; A(int a_):a(a_) {} }; int main() { vector<auto_ptr<A> > as; for (int i = 0; i < 10; i++) { auto_ptr<A> a(new A(i)); as.push_back(a); } for (vector<auto_ptr<A> >::iterator it = as.begin(); it != as.end(); ++it) cout << (*it)->a << endl; } When trying to compile it, I get the following obscure compiler error from g++: g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/proba.d" -MT"src/proba.d" -o"src/proba.o" "../src/proba.cpp" /usr/include/c++/4.1.2/ext/new_allocator.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_vector.h:606: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/ext/new_allocator.h:104: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/vector.tcc: In member function ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’: /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/vector.tcc:256: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/stl_construct.h: In function ‘void std::_Construct(_T1*, const _T2&) [with _T1 = std::auto_ptr<A>, _T2 = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_uninitialized.h:86: instantiated from ‘_ForwardIterator std::__uninitialized_copy_aux(_InputIterator, _InputIterator, _ForwardIterator, __false_type) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:113: instantiated from ‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:254: instantiated from ‘_ForwardIterator std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator, std::allocator<_Tp>) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _Tp = std::auto_ptr<A>]’ /usr/include/c++/4.1.2/bits/vector.tcc:279: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/stl_construct.h:81: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers make: *** [src/proba.o] Error 1 It seems to me that there is some kind of problem with consts here. Does this mean that auto_ptr can't be used in vectors?

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  • removeFirst and addLast methods of LinkedList Class are Unknown

    - by user318068
    I have a problem with my code in C# . if i click in compiler button , I get the following errors 'System.Collections.Generic.LinkedList<int?>' does not contain a definition for 'removeFirst' and no extension method 'removeFirst' accepting a first argument of type 'System.Collections.Generic.LinkedList<int?>' could be found (are you missing a using directive or an assembly reference?). and 'System.Collections.Generic.LinkedList<Hanoi_tower.Sol>' does not contain a definition for 'addLast' and no extension method 'addLast' accepting a first argument of type 'System.Collections.Generic.LinkedList<Hanoi_tower.Sol>' could be found (are you missing a using directive or an assembly reference?) This is my program using System.; using System.Collections.Generic; using System.Linq; using System.Text; namespace Hanoi_tower { public class Sol { public LinkedList<int?> tower1 = new LinkedList<int?>(); public LinkedList<int?> tower2 =new LinkedList<int?>(); public LinkedList<int?> tower3 =new LinkedList<int?>(); public int depth; public LinkedList<Sol> neighbors; public Sol(LinkedList<int?> tower1, LinkedList<int?> tower2, LinkedList<int?> tower3) { this.tower1 = tower1; this.tower2 = tower2; this.tower3 = tower3; neighbors = new LinkedList<Sol>(); } public virtual void getneighbors() { Sol temp = this.copy(); Sol neighbor1 = this.copy(); Sol neighbor2 = this.copy(); Sol neighbor3 = this.copy(); Sol neighbor4 = this.copy(); Sol neighbor5 = this.copy(); Sol neighbor6 = this.copy(); if (temp.tower1.Count != 0) { if (neighbor1.tower2.Count != 0) { if (neighbor1.tower1.First.Value < neighbor1.tower2.First.Value) { neighbor1.tower2.AddFirst(neighbor1.tower1.RemoveFirst); neighbors.AddLast(neighbor1); } } else { neighbor1.tower2.AddFirst(neighbor1.tower1.RemoveFirst()); neighbors.AddLast(neighbor1); } if (neighbor2.tower3.Count != 0) { if (neighbor2.tower1.First.Value < neighbor2.tower3.First.Value) { neighbor2.tower3.AddFirst(neighbor2.tower1.RemoveFirst()); neighbors.AddLast(neighbor2); } } else { neighbor2.tower3.AddFirst(neighbor2.tower1.RemoveFirst()); neighbors.AddLast(neighbor2); } } //------------- if (temp.tower2.Count != 0) { if (neighbor3.tower1.Count != 0) { if (neighbor3.tower2.First.Value < neighbor3.tower1.First.Value) { neighbor3.tower1.AddFirst(neighbor3.tower2.RemoveFirst()); neighbors.AddLast(neighbor3); } } else { neighbor3.tower1.AddFirst(neighbor3.tower2.RemoveFirst()); neighbors.AddLast(neighbor3); } if (neighbor4.tower3.Count != 0) { if (neighbor4.tower2.First.Value < neighbor4.tower3.First.Value) { neighbor4.tower3.AddFirst(neighbor4.tower2.RemoveFirst()); neighbors.AddLast(neighbor4); } } else { neighbor4.tower3.AddFirst(neighbor4.tower2.RemoveFirst()); neighbors.AddLast(neighbor4); } } //------------------------ if (temp.tower3.Count() != 0) { if (neighbor5.tower1.Count() != 0) { if(neighbor5.tower3.ElementAtOrDefault() < neighbor5.tower1.ElementAtOrDefault()) { neighbor5.tower1.AddFirst(neighbor5.tower3.RemoveFirst()); neighbors.AddLast(neighbor5); } } else { neighbor5.tower1.AddFirst(neighbor5.tower3.RemoveFirst()); neighbors.AddLast(neighbor5); } if (neighbor6.tower2.Count() != 0) { if(neighbor6.tower3.element() < neighbor6.tower2.element()) { neighbor6.tower2.addFirst(neighbor6.tower3.removeFirst()); neighbors.addLast(neighbor6); } } else { neighbor6.tower2.addFirst(neighbor6.tower3.removeFirst()); neighbors.addLast(neighbor6); } } } public override string ToString() { string str; str="tower1"+ tower1.ToString() + " tower2" + tower2.ToString() + " tower3" + tower3.ToString(); return str; } public Sol copy() { Sol So; LinkedList<int> l1= new LinkedList<int>(); LinkedList<int> l2=new LinkedList<int>(); LinkedList<int> l3 = new LinkedList<int>(); for(int i=0;i<=this.tower1.Count() -1;i++) { l1.AddLast(tower1.get(i)); } for(int i=0;i<=this.tower2.size()-1;i++) { l2.addLast(tower2.get(i)); } for(int i=0;i<=this.tower3.size()-1;i++) { l3.addLast(tower3.get(i)); } So = new Sol(l1, l2, l3); return So; } public bool Equals(Sol sol) { if (this.tower1.Equals(sol.tower1) & this.tower2.Equals(sol.tower2) & this.tower3.Equals(sol.tower3)) return true; return false; } public virtual bool containedin(Stack<Sol> vec) { bool found =false; for(int i=0;i<= vec.Count-1;i++) { if(vec.get(i).tower1.Equals(this.tower1) && vec.get(i).tower2.Equals(this.tower2) && vec.get(i).tower3.Equals(this.tower3)) { found=true; break; } } return found; } } }

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  • Using WeakReference to resolve issue with .NET unregistered event handlers causing memory leaks.

    - by Eric
    The problem: Registered event handlers create a reference from the event to the event handler's instance. If that instance fails to unregister the event handler (via Dispose, presumably), then the instance memory will not be freed by the garbage collector. Example: class Foo { public event Action AnEvent; public void DoEvent() { if (AnEvent != null) AnEvent(); } } class Bar { public Bar(Foo l) { l.AnEvent += l_AnEvent; } void l_AnEvent() { } } If I instantiate a Foo, and pass this to a new Bar constructor, then let go of the Bar object, it will not be freed by the garbage collector because of the AnEvent registration. I consider this a memory leak, and seems just like my old C++ days. I can, of course, make Bar IDisposable, unregister the event in the Dispose() method, and make sure to call Dispose() on instances of it, but why should I have to do this? I first question why events are implemented with strong references? Why not use weak references? An event is used to abstractly notify an object of changes in another object. It seems to me that if the event handler's instance is no longer in use (i.e., there are no non-event references to the object), then any events that it is registered with should automatically be unregistered. What am I missing? I have looked at WeakEventManager. Wow, what a pain. Not only is it very difficult to use, but its documentation is inadequate (see http://msdn.microsoft.com/en-us/library/system.windows.weakeventmanager.aspx -- noticing the "Notes to Inheritors" section that has 6 vaguely described bullets). I have seen other discussions in various places, but nothing I felt I could use. I propose a simpler solution based on WeakReference, as described here. My question is: Does this not meet the requirements with significantly less complexity? To use the solution, the above code is modified as follows: class Foo { public WeakReferenceEvent AnEvent = new WeakReferenceEvent(); internal void DoEvent() { AnEvent.Invoke(); } } class Bar { public Bar(Foo l) { l.AnEvent += l_AnEvent; } void l_AnEvent() { } } Notice two things: 1. The Foo class is modified in two ways: The event is replaced with an instance of WeakReferenceEvent, shown below; and the invocation of the event is changed. 2. The Bar class is UNCHANGED. No need to subclass WeakEventManager, implement IWeakEventListener, etc. OK, so on to the implementation of WeakReferenceEvent. This is shown here. Note that it uses the generic WeakReference that I borrowed from here: http://damieng.com/blog/2006/08/01/implementingweakreferencet I had to add Equals() and GetHashCode() to his class, which I include below for reference. class WeakReferenceEvent { public static WeakReferenceEvent operator +(WeakReferenceEvent wre, Action handler) { wre._delegates.Add(new WeakReference<Action>(handler)); return wre; } public static WeakReferenceEvent operator -(WeakReferenceEvent wre, Action handler) { foreach (var del in wre._delegates) if (del.Target == handler) { wre._delegates.Remove(del); return wre; } return wre; } HashSet<WeakReference<Action>> _delegates = new HashSet<WeakReference<Action>>(); internal void Invoke() { HashSet<WeakReference<Action>> toRemove = null; foreach (var del in _delegates) { if (del.IsAlive) del.Target(); else { if (toRemove == null) toRemove = new HashSet<WeakReference<Action>>(); toRemove.Add(del); } } if (toRemove != null) foreach (var del in toRemove) _delegates.Remove(del); } } public class WeakReference<T> : IDisposable { private GCHandle handle; private bool trackResurrection; public WeakReference(T target) : this(target, false) { } public WeakReference(T target, bool trackResurrection) { this.trackResurrection = trackResurrection; this.Target = target; } ~WeakReference() { Dispose(); } public void Dispose() { handle.Free(); GC.SuppressFinalize(this); } public virtual bool IsAlive { get { return (handle.Target != null); } } public virtual bool TrackResurrection { get { return this.trackResurrection; } } public virtual T Target { get { object o = handle.Target; if ((o == null) || (!(o is T))) return default(T); else return (T)o; } set { handle = GCHandle.Alloc(value, this.trackResurrection ? GCHandleType.WeakTrackResurrection : GCHandleType.Weak); } } public override bool Equals(object obj) { var other = obj as WeakReference<T>; return other != null && Target.Equals(other.Target); } public override int GetHashCode() { return Target.GetHashCode(); } } It's functionality is trivial. I override operator + and - to get the += and -= syntactic sugar matching events. These create WeakReferences to the Action delegate. This allows the garbage collector to free the event target object (Bar in this example) when nobody else is holding on to it. In the Invoke() method, simply run through the weak references and call their Target Action. If any dead (i.e., garbage collected) references are found, remove them from the list. Of course, this only works with delegates of type Action. I tried making this generic, but ran into the missing where T : delegate in C#! As an alternative, simply modify class WeakReferenceEvent to be a WeakReferenceEvent, and replace the Action with Action. Fix the compiler errors and you have a class that can be used like so: class Foo { public WeakReferenceEvent<int> AnEvent = new WeakReferenceEvent<int>(); internal void DoEvent() { AnEvent.Invoke(5); } } Hopefully this will help someone else when they run into the mystery .NET event memory leak!

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  • Compilng problems with vector<auto_ptr<> >

    - by petersohn
    Consider the following code: #include <iostream> #include <memory> #include <vector> using namespace std; struct A { int a; A(int a_):a(a_) {} }; int main() { vector<auto_ptr<A> > as; for (int i = 0; i < 10; i++) { auto_ptr<A> a(new A(i)); as.push_back(a); } for (vector<auto_ptr<A> >::iterator it = as.begin(); it != as.end(); ++it) cout << (*it)->a << endl; } When trying to compile it, I get the following obscure compiler error from g++: g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/proba.d" -MT"src/proba.d" -o"src/proba.o" "../src/proba.cpp" /usr/include/c++/4.1.2/ext/new_allocator.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_vector.h:606: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/ext/new_allocator.h:104: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/vector.tcc: In member function ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’: /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/vector.tcc:256: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/stl_construct.h: In function ‘void std::_Construct(_T1*, const _T2&) [with _T1 = std::auto_ptr<A>, _T2 = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_uninitialized.h:86: instantiated from ‘_ForwardIterator std::__uninitialized_copy_aux(_InputIterator, _InputIterator, _ForwardIterator, __false_type) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:113: instantiated from ‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:254: instantiated from ‘_ForwardIterator std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator, std::allocator<_Tp>) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _Tp = std::auto_ptr<A>]’ /usr/include/c++/4.1.2/bits/vector.tcc:279: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/stl_construct.h:81: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers make: *** [src/proba.o] Error 1 It seems to me that there is some kind of problem with consts here. Does this mean that auto_ptr can't be used in vectors?

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  • Of these 3 methods for reading linked lists from shared memory, why is the 3rd fastest?

    - by Joseph Garvin
    I have a 'server' program that updates many linked lists in shared memory in response to external events. I want client programs to notice an update on any of the lists as quickly as possible (lowest latency). The server marks a linked list's node's state_ as FILLED once its data is filled in and its next pointer has been set to a valid location. Until then, its state_ is NOT_FILLED_YET. I am using memory barriers to make sure that clients don't see the state_ as FILLED before the data within is actually ready (and it seems to work, I never see corrupt data). Also, state_ is volatile to be sure the compiler doesn't lift the client's checking of it out of loops. Keeping the server code exactly the same, I've come up with 3 different methods for the client to scan the linked lists for changes. The question is: Why is the 3rd method fastest? Method 1: Round robin over all the linked lists (called 'channels') continuously, looking to see if any nodes have changed to 'FILLED': void method_one() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } while(true) { for(std::size_t i = 0; i < channel_list.size(); ++i) { Data* current_item = channel_cursors[i]; ACQUIRE_MEMORY_BARRIER; if(current_item->state_ == NOT_FILLED_YET) { continue; } log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[i] = static_cast<Data*>(current_item->next_.get(segment)); } } } Method 1 gave very low latency when then number of channels was small. But when the number of channels grew (250K+) it became very slow because of looping over all the channels. So I tried... Method 2: Give each linked list an ID. Keep a separate 'update list' to the side. Every time one of the linked lists is updated, push its ID on to the update list. Now we just need to monitor the single update list, and check the IDs we get from it. void method_two() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } UpdateID* update_cursor = static_cast<UpdateID*>(update_channel.tail_.get(segment)); while(true) { if(update_cursor->state_ == NOT_FILLED_YET) { continue; } ::uint32_t update_id = update_cursor->list_id_; Data* current_item = channel_cursors[update_id]; if(current_item->state_ == NOT_FILLED_YET) { std::cerr << "This should never print." << std::endl; // it doesn't continue; } log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[update_id] = static_cast<Data*>(current_item->next_.get(segment)); update_cursor = static_cast<UpdateID*>(update_cursor->next_.get(segment)); } } Method 2 gave TERRIBLE latency. Whereas Method 1 might give under 10us latency, Method 2 would inexplicably often given 8ms latency! Using gettimeofday it appears that the change in update_cursor-state_ was very slow to propogate from the server's view to the client's (I'm on a multicore box, so I assume the delay is due to cache). So I tried a hybrid approach... Method 3: Keep the update list. But loop over all the channels continuously, and within each iteration check if the update list has updated. If it has, go with the number pushed onto it. If it hasn't, check the channel we've currently iterated to. void method_three() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } UpdateID* update_cursor = static_cast<UpdateID*>(update_channel.tail_.get(segment)); while(true) { for(std::size_t i = 0; i < channel_list.size(); ++i) { std::size_t idx = i; ACQUIRE_MEMORY_BARRIER; if(update_cursor->state_ != NOT_FILLED_YET) { //std::cerr << "Found via update" << std::endl; i--; idx = update_cursor->list_id_; update_cursor = static_cast<UpdateID*>(update_cursor->next_.get(segment)); } Data* current_item = channel_cursors[idx]; ACQUIRE_MEMORY_BARRIER; if(current_item->state_ == NOT_FILLED_YET) { continue; } found_an_update = true; log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[idx] = static_cast<Data*>(current_item->next_.get(segment)); } } } The latency of this method was as good as Method 1, but scaled to large numbers of channels. The problem is, I have no clue why. Just to throw a wrench in things: if I uncomment the 'found via update' part, it prints between EVERY LATENCY LOG MESSAGE. Which means things are only ever found on the update list! So I don't understand how this method can be faster than method 2. The full, compilable code (requires GCC and boost-1.41) that generates random strings as test data is at: http://pastebin.com/e3HuL0nr

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  • How to use EJB 3.1 DI in Servlet ? (Could not inject session bean by @EJB from web application)

    - by kislo_metal
    I am tying to merging web application(gwt, jpa) to an separate 2 application(business login in ejb/jpa and web client in gwt). Currently i can`t inject my beans from web application (simple servlet) I am using glassfish v3. module limbo(ejb jar) is in dependency of module lust (war). If I use lust with compiler output of limbo everything work perfect (if ejb in web application and the are deploying together as one application). Have I messed some container configuration ? Here is my steps: I have some limbo.jar (ejb-jar) deployed to ejb container. I do not use any ejb-jar.xml, only annotations. package ua.co.inferno.limbo.persistence.beans; import javax.ejb.Remote; @Remote public interface IPersistentServiceRemote { ArrayList<String> getTerminalACPList(); ArrayList<String> getBoxACPList(); ArrayList<String> getCNPList(); ArrayList<String> getCNSList(); String getProductNamebyID(int boxid); ArrayList<String> getRegionsList(String lang); long getSequence(); void persistEntity (Object ent); } package ua.co.inferno.limbo.persistence.beans; import ua.co.inferno.limbo.persistence.entitis.EsetChSchemaEntity; import ua.co.inferno.limbo.persistence.entitis.EsetKeyActionsEntity; @Local public interface IPersistentService { ArrayList<String> getTerminalACPList(); ArrayList<String> getBoxACPList(); ArrayList<String> getCNPList(); ArrayList<String> getCNSList(); String getProductNamebyID(int boxid); ArrayList<String> getRegionsList(String lang); long getSequence(); long persistPurchaseBox(EsetRegPurchaserEntity rp); void removePurchaseTempBox(EsetRegPurchaserTempEntity rpt); EsetRegionsEntity getRegionsById(long rid); void persistEntity (Object ent); } package ua.co.inferno.limbo.persistence.beans; import ua.co.inferno.limbo.persistence.entitis.EsetChSchemaEntity; import ua.co.inferno.limbo.persistence.entitis.EsetKeyActionsEntity; import ua.co.inferno.limbo.persistence.entitis.EsetRegBoxesEntity; import javax.ejb.Stateless; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; @Stateless(name = "PersistentService") public class PersistentServiceEJB implements IPersistentService, IPersistentServiceRemote{ @PersistenceContext(unitName = "Limbo") EntityManager em; public PersistentServiceEJB() { } ......... } Than i trying to use PersistentService session bean(included in limbo.jar) from web application in lust.war (the limbo.jar & lust.war is not in ear) package ua.co.lust; import ua.co.inferno.limbo.persistence.beans.IPersistentService; import javax.ejb.EJB; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; @WebServlet(name = "ServletTest", urlPatterns = {"/"}) public class ServletTest extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { service(request, response); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { service(request, response); } @EJB private IPersistentService pService; public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String hi = pService.getCNPList().toString(); System.out.println("testBean.hello method returned: " + hi); System.out.println("In MyServlet::init()"); System.out.println("all regions" + pService.getRegionsList("ua")); System.out.println("all regions" + pService.getBoxACPList()); } } web.xm <?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> <servlet> <servlet-name>ServletTest</servlet-name> <servlet-class>ua.co.lust.ServletTest</servlet-class> </servlet> </web-app> When servelt is loading i ge 404 eror (The requested resource () is not available.) And errors in logs : global Log Level SEVERE Logger global Name-Value Pairs {_ThreadName=Thread-1, _ThreadID=31} Record Number 1421 Message ID Complete Message Class [ Lua/co/inferno/limbo/persistence/beans/IPersistentService; ] not found. Error while loading [ class ua.co.lust.ServletTest ] javax.enterprise.system.tools.deployment.org.glassfish.deployment.common Log Level WARNING Logger javax.enterprise.system.tools.deployment.org.glassfish.deployment.common Name-Value Pairs {_ThreadName=Thread-1, _ThreadID=31} Record Number 1422 Message ID Error in annotation processing Complete Message java.lang.NoClassDefFoundError: Lua/co/inferno/limbo/persistence/beans/IPersistentService; ejb jar was deployed with this info log : Log Level INFO Logger javax.enterprise.system.container.ejb.com.sun.ejb.containers Name-Value Pairs {_ThreadName=Thread-1, _ThreadID=26} Record Number 1436 Message ID Glassfish-specific (Non-portable) JNDI names for EJB PersistentService Complete Message [ua.co.inferno.limbo.persistence.beans.IPersistentServiceRemote#ua.co.inferno.limbo.persistence.beans.IPersistentServiceRemote, ua.co.inferno.limbo.persistence.beans.IPersistentServiceRemote] Log Level INFO Logger javax.enterprise.system.tools.admin.org.glassfish.deployment.admin Name-Value Pairs {_ThreadName=Thread-1, _ThreadID=26} Record Number 1445 Message ID Complete Message limbo was successfully deployed in 610 milliseconds. Do i nee to add some additional configuration in a case of injections from others application? Some ideas?

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  • Maven Release Plugin with JAXB issues

    - by Wysawyg
    Hiya, We've got a project set up to use the Maven Release Plugin which includes a phase that unpacks a JAR of XML schemas pulled from Artifactory and a phase that generates XJC classes. We're on maven release 2.2.1. Unfortunately the latter phase is executing before the former which means that it isn't generating the XJC classes for the schema. A partial POM.XML looks like: <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.6</source> <target>1.6</target> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-dependency-plugin</artifactId> <executions> <execution> <id>unpack</id> <!-- phase>generate-sources</phase --> <goals> <goal>unpack</goal> <goal>copy</goal> </goals> <configuration> <artifactItems> <artifactItem> <groupId>ourgroupid</groupId> <artifactId>ourschemas</artifactId> <version>5.1</version> <outputDirectory>${project.basedir}/src/main/webapp/xsd</outputDirectory> <excludes>META-INF/</excludes> <overWrite>true</overWrite> </artifactItem> </artifactItems> </configuration> </execution> </executions> </plugin> <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>maven-buildnumber-plugin</artifactId> <version>0.9.6</version> <executions> <execution> <phase>validate</phase> <goals> <goal>create</goal> </goals> </execution> </executions> <configuration> <doCheck>true</doCheck> <doUpdate>true</doUpdate> </configuration> </plugin> <plugin> <groupId>org.jvnet.jaxb2.maven2</groupId> <artifactId>maven-jaxb2-plugin</artifactId> <configuration> <schemaDirectory>${project.basedir}/src/main/webapp/xsd</schemaDirectory> <schemaIncludes> <include>*.xsd</include> <include>*/*.xsd</include> </schemaIncludes> <verbose>true</verbose> <!-- args> <arg>-Djavax.xml.validation.SchemaFactory:http://www.w3.org/2001/XMLSchema=org.apache.xerces.jaxp.validation.XMLSchemaFactory</arg> </args--> </configuration> <executions> <execution> <goals> <goal>generate</goal> </goals> </execution> </executions> </plugin> I've tried googling for it, unfortunately I ended up with a case of thousands of links none of which were actually relevant so I'd be very grateful if someone knew how to configure the order of the release plugin steps to ensure a was fully executed before it did b. Thanks

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  • How do I add the j2ee.jar to a Java2WSDL ant script programmatically?

    - by Marcus
    I am using IBM's Rational Application Developer. I have an ant script that contains the Java2WSDL task. When I run it via IBM, it gives compiler errors unless I include the j2ee.jar file in the classpath via the run tool (it does not pick up the jar files in the classpath in the script). However, I need to be able to call this script programmatically, and it is giving me this error: "java.lang.NoClassDefFoundError: org.eclipse.core.runtime.CoreException" I'm not sure which jars need to be added or where? Since a simple echo script runs, I assume that it is the j2ee.jar or another ant jar that needs to be added. I've added it to the project's buildpath, but that doesn't help. (I also have ant.jar, wsanttasks.jar, all the ant jars from the plugin, tools.jar, remoteAnt.jar, and the swt - all which are included in the buildpath when you run the script by itself.) Script: <?xml version="1.0" encoding="UTF-8"?> <project default="build" basedir="."> <path id="lib.path"> <fileset dir="C:\Program Files\IBM\WebSphere\AppServer\lib" includes="*.jar"/> <!-- Adding these does not help. <fileset dir="C:\Program Files\IBM\SDP70Shared\plugins\org.apache.ant_1.6.5\lib" includes="*.jar"/> <fileset dir="C:\Program Files\IBM\SDP70\jdk\lib" includes="*.jar"/> <fileset dir="C:\Program Files\IBM\SDP70\configuration\org.eclipse.osgi\bundles\1139\1\.cp\lib" includes="*.jar"/> <fileset dir="C:\Program Files\IBM\SDP70Shared\plugins" includes="*.jar"/> --> </path> <taskdef name="java2wsdl" classname="com.ibm.websphere.ant.tasks.Java2WSDL"> <classpath refid="lib.path"/> </taskdef> <target name="build"> <echo message="Beginning build"/> <javac srcdir="C:\J2W_Test\Java2Wsdl_Example" destdir="C:\J2W_Test\Java2Wsdl_Example"> <classpath refid="lib.path"/> <include name="WSExample.java"/> </javac> <echo message="Set up javac"/> <echo message="Running java2wsdl"/> <java2wsdl output="C:\J2W_Test\Java2Wsdl_Example\example\META-INF\wsdl\WSExample.wsdl" classpath="C:\J2W_Test\Java2Wsdl_Example" className= "example.WSExample" namespace="http://example" namespaceImpl="http://example" location="http://localhost:9080/example/services/WSExample" style="document" use="literal"> <mapping namespace="http://example" package="example"/> </java2wsdl> <echo message="Complete"/> </target> </project> Code: File buildFile = new File("build.xml"); Project p = new Project(); p.setUserProperty("ant.file", buildFile.getAbsolutePath()); DefaultLogger consoleLogger = new DefaultLogger(); consoleLogger.setErrorPrintStream(System.err); consoleLogger.setOutputPrintStream(System.out); consoleLogger.setMessageOutputLevel(Project.MSG_INFO); p.addBuildListener(consoleLogger); try { p.fireBuildStarted(); p.init(); ProjectHelper helper = ProjectHelper.getProjectHelper(); p.addReference("ant.projectHelper", helper); helper.parse(p, buildFile); p.executeTarget(p.getDefaultTarget()); p.fireBuildFinished(null); } catch (BuildException e) { p.fireBuildFinished(e); } Error: [java2wsdl] java.lang.NoClassDefFoundError: org.eclipse.core.runtime.CoreException [java2wsdl] at java.lang.J9VMInternals.verifyImpl(Native Method) [java2wsdl] at java.lang.J9VMInternals.verify(J9VMInternals.java:68) [java2wsdl] at java.lang.J9VMInternals.initialize(J9VMInternals.java:129) [java2wsdl] at com.ibm.ws.webservices.multiprotocol.discovery.ServiceProviderManager.getDiscoveredServiceProviders(ServiceProviderManager.java:378) [java2wsdl] at com.ibm.ws.webservices.multiprotocol.discovery.ServiceProviderManager.getAllServiceProviders(ServiceProviderManager.java:214) [java2wsdl] at com.ibm.ws.webservices.wsdl.fromJava.Emitter.initPluggableBindings(Emitter.java:2704) [java2wsdl] at com.ibm.ws.webservices.wsdl.fromJava.Emitter.<init>(Emitter.java:389) [java2wsdl] at com.ibm.ws.webservices.tools.ant.Java2WSDL.execute(Java2WSDL.java:122) [java2wsdl] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275) [java2wsdl] at org.apache.tools.ant.Task.perform(Task.java:364) [java2wsdl] at org.apache.tools.ant.Target.execute(Target.java:341) [java2wsdl] at org.apache.tools.ant.Target.performTasks(Target.java:369) [java2wsdl] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1216) [java2wsdl] at org.apache.tools.ant.Project.executeTarget(Project.java:1185) [java2wsdl] at att.ant.RunAnt.main(RunAnt.java:32)

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  • Why does calling IEnumerable<string>.Count() create an additional assembly dependency ?

    - by Gishu
    Assume this chain of dll references Tests.dll >> Automation.dll >> White.Core.dll with the following line of code in Tests.dll, where everything builds result.MissingPaths Now when I change this to result.MissingPaths.Count() I get the following build error for Tests.dll "White.UIItem is not defined in an assembly that is not referenced. You must add a reference to White.Core.dll." And I don't want to do that because it breaks my layering. Here is the type definition for result, which is in Automation.dll public class HasResult { public HasResult(IEnumerable<string> missingPaths ) { MissingPaths = missingPaths; } public IEnumerable<string> MissingPaths { get; set; } public bool AllExist { get { return !MissingPaths.Any(); } } } Down the call chain the input param to this ctor is created via (The TreeNode class is in White.Core.dll) assetPaths.Where(assetPath => !FindTreeNodeUsingCache(treeHandle, assetPath)); Why does this dependency leak when calling Count() on IEnumerable ? I then suspected that lazy evaluation was causing this (for some reason) - so I slotted in an ToArray() in the above line but didn't work. Update 2011 01 07: Curiouser and Curiouser! it won't build until I add a White.Core reference. So I add a reference and build it (in order to find the elusive dependency source). Open it up in Reflector and the only references listed are Automation, mscorlib, System.core and NUnit. So the compiler threw away the White reference as it was not needed. ILDASM also confirms that there is no White AssemblyRef entry. Any ideas on how to get to the bottom of this thing (primarily for 'now I wanna know why' reasons)? What are the chances that this is an VS2010/MSBuild bug? Update 2011 01 07 #2 As per Shimmy's suggestion, tried calling the method explcitly as an extension method Enumerable.Count(result.MissingPaths) and it stops cribbing (not sure why). However I moved some code around after that and now I'm getting the same issue at a different location using IEnumerable - this time reading and filtering lines out of a file on disk (totally unrelated to White). Seems like it's a 'symptom-fix'. var lines = File.ReadLines(aFilePath).ToArray(); once again, if I remove the ToArray() it compiles again - it seems that any method that causes the enumerable to be evaluated (ToArray, Count, ToList, etc.) causes this. Let me try and get a working tiny-app to demo this issue... Update 2011 01 07 #3 Phew! More information.. It turns out the problem is just in one source file - this file is LINQ-phobic. Any call to an Enumerable extension method has to be explicitly called out. The refactorings that I did caused a new method to be moved into this source file, which had some LINQ :) Still no clue as to why this class dislikes LINQ. using System; using System.Collections.Generic; using System.IO; using System.Linq; using G.S.OurAutomation.Constants; using G.S.OurAutomation.Framework; using NUnit.Framework; namespace G.S.AcceptanceTests { public abstract class ConfigureThingBase : OurTestFixture { .... private static IEnumerable<string> GetExpectedThingsFor(string param) { // even this won't compile - although it compiles fine in an adjoining source file in the same assembly //IEnumerable<string> s = new string[0]; //Console.WriteLine(s.Count()); // this is the line that is now causing a build failure // var expectedInfo = File.ReadLines(someCsvFilePath)) // .Where(line => !line.StartsWith("REM", StringComparison.InvariantCultureIgnoreCase)) // .Select(line => line.Replace("%PLACEHOLDER%", param)) // .ToArray(); // Unrolling the LINQ above removes the build error var expectedInfo = Enumerable.ToArray( Enumerable.Select( Enumerable.Where( File.ReadLines(someCsvFilePath)), line => !line.StartsWith("REM", StringComparison.InvariantCultureIgnoreCase)), line => line.Replace("%PLACEHOLDER%", param)));

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  • Anyone succeeded at injecting Interfaces into Entity Framework 4 Entities, using T4?

    - by Ciel
    Hello: POCO sort of leaves me wanting: (how can I say I use DI/IoC, if the Repository is not the only place that is creating the entities?)...hence my desire to lock it down, get rid of the temptation of newing up POCOs or EntityObjects anywhere in the code, and just allowing entity interfaces above the Repository/Factory layer. For a second there, I nearly thought I had it...was editing EF4's T4 in order to inject in an Interface def. Was going swimmingly, compiled and worked, until I got to the Associations... I wrapped them with a ICollection, and renamed the underlying original collection with a prefix of Wrapped. Unfortunately, when run, throws an error: //The Member 'WrappedSubExamples' in the CLR type 'XAct.App.Data.Model.EF4.Example' is not present in the conceptual model type 'XAct.App.Data.Model.Entity.Example'. var examples = context2.CreateObjectSet(); My T4 segment I used was (this may not work, as it's the longest code snippet I've ever posted here...sorry): #region Generic Property Abstraction <# if (navProperty.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many) {#> //XAct.App Generic Wrapper: <#=code.SpaceAfter(NewModifier(navProperty))#><#=Accessibility.ForProperty(navProperty)#> ICollection<I<#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)#>> <#=code.Escape(navProperty)#> { get { if (_X<#=code.Escape(navProperty)# == null){ _X<#=code.Escape(navProperty)# = new WrappedCollection,<#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)#(this.<#=(navProperty.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many)?"Wrapped":""#<#=code.Escape(navProperty)#); } return _X<#=code.Escape(navProperty)#; } } private ICollection _X<#=code.Escape(navProperty)#; <# } else { # <#=code.SpaceAfter(NewModifier(navProperty))#<#=Accessibility.ForProperty(navProperty)# I<#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)# <#=code.Escape(navProperty)# { get { return (I<#=code.Escape(navProperty)#)this.Wrapped<#=code.Escape(navProperty)#; } set { this.Wrapped<#=code.Escape(navProperty)# = value as <#=code.Escape(navProperty)#; } } <# } # #endregion which then wraps the original collection, renamed with the prefix 'Wrapped': /// <summary> /// <#=SummaryComment(navProperty)#> /// </summary><#=LongDescriptionCommentElement(navProperty, region.CurrentIndentLevel) #> [XmlIgnoreAttribute()] [SoapIgnoreAttribute()] [DataMemberAttribute()] [EdmRelationshipNavigationPropertyAttribute("<#=navProperty.RelationshipType.NamespaceName#>", "<#=navProperty.RelationshipType.Name#>", "<#=navProperty.ToEndMember.Name#>")] <# if (navProperty.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many) { #> <#=code.SpaceAfter(NewModifier(navProperty))#><#=Accessibility.ForProperty(navProperty)#> EntityCollection<<#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)#>> Wrapped<#=code.Escape(navProperty)#> { <#=code.SpaceAfter(Accessibility.ForGetter(navProperty))#>get { return ((IEntityWithRelationships)this).RelationshipManager.GetRelatedCollection<<#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)#>>("<#=navProperty.RelationshipType.FullName#>", "<#=navProperty.ToEndMember.Name#>"); } <#=code.SpaceAfter(Accessibility.ForSetter(navProperty))#>set { if ((value != null)) { ((IEntityWithRelationships)this).RelationshipManager.InitializeRelatedCollection<<#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)#>>("<#=navProperty.RelationshipType.FullName#>", "<#=navProperty.ToEndMember.Name#>", value); } } } <# } else { #> <#=code.SpaceAfter(NewModifier(navProperty))#><#=Accessibility.ForProperty(navProperty)#> <#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)#> Wrapped<#=code.Escape(navProperty)#> { <#=code.SpaceAfter(Accessibility.ForGetter(navProperty))#>get { return ((IEntityWithRelationships)this).RelationshipManager.GetRelatedReference<<#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)#>>("<#=navProperty.RelationshipType.FullName#>", "<#=navProperty.ToEndMember.Name#>").Value; } <#=code.SpaceAfter(Accessibility.ForSetter(navProperty))#>set { ((IEntityWithRelationships)this).RelationshipManager.GetRelatedReference<<#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)#>>("<#=navProperty.RelationshipType.FullName#>", "<#=navProperty.ToEndMember.Name#>").Value = value; } } <# string refPropertyName = navProperty.Name + "Reference"; if (entity.Members.Any(m => m.Name == refPropertyName)) { // 6017 is the same error number that EntityClassGenerator uses. Errors.Add(new System.CodeDom.Compiler.CompilerError(SourceCsdlPath, -1, -1, "6017", String.Format(CultureInfo.CurrentCulture, GetResourceString("Template_ConflictingGeneratedNavPropName"), navProperty.Name, entity.FullName, refPropertyName))); } #> /// <summary> /// <#=SummaryComment(navProperty)#> /// </summary><#=LongDescriptionCommentElement(navProperty, region.CurrentIndentLevel)#> [BrowsableAttribute(false)] [DataMemberAttribute()] <#=Accessibility.ForProperty(navProperty)#> EntityReference<<#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)#>> <#=refPropertyName#> { <#=code.SpaceAfter(Accessibility.ForGetter(navProperty))#>get { return ((IEntityWithRelationships)this).RelationshipManager.GetRelatedReference<<#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)#>>("<#=navProperty.RelationshipType.FullName#>", "<#=navProperty.ToEndMember.Name#>"); } <#=code.SpaceAfter(Accessibility.ForSetter(navProperty))#>set { if ((value != null)) { ((IEntityWithRelationships)this).RelationshipManager.InitializeRelatedReference<<#=MultiSchemaEscape(navProperty.ToEndMember.GetEntityType(), code)#>>("<#=navProperty.RelationshipType.FullName#>", "<#=navProperty.ToEndMember.Name#>", value); } } } <# } The point is...it bugs out. I've tried various solutions...none worked. Any ideas -- or is this just a wild goose chase, and time to give it up?

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  • Making swap faster, easier to use and exception-safe

    - by FredOverflow
    I could not sleep last night and started thinking about std::swap. Here is the familiar C++98 version: template <typename T> void swap(T& a, T& b) { T c(a); a = b; b = c; } If a user-defined class Foo uses external ressources, this is inefficient. The common idiom is to provide a method void Foo::swap(Foo& other) and a specialization of std::swap<Foo>. Note that this does not work with class templates since you cannot partially specialize a function template, and overloading names in the std namespace is illegal. The solution is to write a template function in one's own namespace and rely on argument dependent lookup to find it. This depends critically on the client to follow the "using std::swap idiom" instead of calling std::swap directly. Very brittle. In C++0x, if Foo has a user-defined move constructor and a move assignment operator, providing a custom swap method and a std::swap<Foo> specialization has little to no performance benefit, because the C++0x version of std::swap uses efficient moves instead of copies: #include <utility> template <typename T> void swap(T& a, T& b) { T c(std::move(a)); a = std::move(b); b = std::move(c); } Not having to fiddle with swap anymore already takes a lot of burden away from the programmer. Current compilers do not generate move constructors and move assignment operators automatically yet, but as far as I know, this will change. The only problem left then is exception-safety, because in general, move operations are allowed to throw, and this opens up a whole can of worms. The question "What exactly is the state of a moved-from object?" complicates things further. Then I was thinking, what exactly are the semantics of std::swap in C++0x if everything goes fine? What is the state of the objects before and after the swap? Typically, swapping via move operations does not touch external resources, only the "flat" object representations themselves. So why not simply write a swap template that does exactly that: swap the object representations? #include <cstring> template <typename T> void swap(T& a, T& b) { unsigned char c[sizeof(T)]; memcpy( c, &a, sizeof(T)); memcpy(&a, &b, sizeof(T)); memcpy(&b, c, sizeof(T)); } This is as efficient as it gets: it simply blasts through raw memory. It does not require any intervention from the user: no special swap methods or move operations have to be defined. This means that it even works in C++98 (which does not have rvalue references, mind you). But even more importantly, we can now forget about the exception-safety issues, because memcpy never throws. I can see two potential problems with this approach: First, not all objects are meant to be swapped. If a class designer hides the copy constructor or the copy assignment operator, trying to swap objects of the class should fail at compile-time. We can simply introduce some dead code that checks whether copying and assignment are legal on the type: template <typename T> void swap(T& a, T& b) { if (false) // dead code, never executed { T c(a); // copy-constructible? a = b; // assignable? } unsigned char c[sizeof(T)]; std::memcpy( c, &a, sizeof(T)); std::memcpy(&a, &b, sizeof(T)); std::memcpy(&b, c, sizeof(T)); } Any decent compiler can trivially get rid of the dead code. (There are probably better ways to check the "swap conformance", but that is not the point. What matters is that it's possible). Second, some types might perform "unusual" actions in the copy constructor and copy assignment operator. For example, they might notify observers of their change. I deem this a minor issue, because such kinds of objects probably should not have provided copy operations in the first place. Please let me know what you think of this approach to swapping. Would it work in practice? Would you use it? Can you identify library types where this would break? Do you see additional problems? Discuss!

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  • ClassCastException happens when I use maven with tomcat plugin

    - by zjffdu
    Hi all, I try to use maven with tomcat plugin to develop a simple web application. But When I invoke the servlet, ClassCastException happens, this is the error message: java.lang.ClassCastException: "com.snda.dw.moniter.LogQueryServlet cannot be to javax.servlet.Servlet" But I already make com.snda.dw.moniter.LogQueryServlet extends HttpServlet, it should can be cast to avax.servlet.Servlet. The following is my pom.xml http://maven.apache.org/maven-v4_0_0.xsd" 4.0.0 com.snda dw.moniter war 0.0.1-SNAPSHOT dw.moniter Maven Webapp http://maven.apache.org junit junit 3.8.1 test <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.4</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>jsp-api</artifactId> <version>2.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>com.google.guava</groupId> <artifactId>guava</artifactId> <version>r07</version> <type>jar</type> <scope>compile</scope> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>1.6.1</version> <type>jar</type> <scope>compile</scope> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-simple</artifactId> <version>1.6.1</version> <type>jar</type> <scope>compile</scope> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-core</artifactId> <version>0.20.2</version> <type>jar</type> <scope>compile</scope> </dependency> <dependency> <groupId>com.snda</groupId> <artifactId>dw.common</artifactId> <version>1.0-SNAPSHOT</version> <type>jar</type> <scope>compile</scope> </dependency> <dependency> <groupId>net.sf.flexjson</groupId> <artifactId>flexjson</artifactId> <version>2.1</version> <type>jar</type> <scope>compile</scope> </dependency> </dependencies> <build> <finalName>dw.moniter</finalName> <pluginManagement> <plugins> <plugin> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.5</source> <target>1.5</target> </configuration> </plugin> <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>tomcat-maven-plugin</artifactId> <version>1.1</version> </plugin> <plugin> <groupId>org.mortbay.jetty</groupId> <artifactId>jetty-maven-plugin</artifactId> <version>8.0.0.M2</version> </plugin> </plugins> </pluginManagement> </build>

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  • ASP.net MVC 2.0 using the same form for adding and editing.

    - by Chevex
    I would like to use the same view for editing a blog post and adding a blog post. However, I'm having an issue with the ID. When adding a blog post, I have no need for an ID value to be posted. When model binding binds the form values to the BlogPost object in the controller, it will auto-generate the ID in entity framework entity. When I am editing a blog post I DO need a hidden form field to store the ID in so that it accompanies the next form post. Here is the view I have right now. <% using (Html.BeginForm("CommitEditBlogPost", "Admin")) { %> <% if (Model != null) { %> <%: Html.HiddenFor(x => x.Id)%> <% } %> Title:<br /> <%: Html.TextBoxFor(x => x.Title, new { Style = "Width: 90%;" })%> <br /> <br /> Summary:<br /> <%: Html.TextAreaFor(x => x.Summary, new { Style = "Width: 90%; Height: 50px;" }) %> <br /> <br /> Body:<br /> <%: Html.TextAreaFor(x => x.Body, new { Style = "Height: 250px; Width: 90%;" })%> <br /> <br /> <input type="submit" value="Submit" /> <% } %> Right now checking if the model is coming in NULL is a great way to know if I'm editing a blog post or adding one, because when I'm adding one it will be null as it hasn't been created yet. The problem comes in when there is an error and the entity is invalid. When the controller renders the form after an invalid model the Model != null evaluates to false, even though we are editing a post and there is clearly a model. If I render the hidden input field for ID when adding a post, I get an error stating that the ID can't be null. Any help is appreciated. EDIT: I went with OJ's answer for this question, however I discovered something that made me feel silly and I wanted to share it just in case anyone was having a similar issue. The page the adds/edits blogs does not even need a hidden field for id, ever. The reason is because when I go to add a blog I do a GET to this relative URL BlogProject/Admin/AddBlogPost This URL does not contain an ID and the action method just renders the page. The page does a POST to the same URL when adding the blog post. The incoming BlogPost entity has a null Id and is generated by EF during save changes. The same thing happens when I edit blog posts. The URL is BlogProject/Admin/EditBlogPost/{Id} This URL contains the id of the blog post and since the page is posting back to the exact same URL the id goes with the POST to the action method that executes the edit. The only problem I encountered with this is that the action methods cannot have identical signatures. [HttpGet] public ViewResult EditBlogPost(int Id) { } [HttpPost] public ViewResult EditBlogPost(int Id) { } The compiler will yell at you if you try to use these two methods above. It is far too convenient that the Id will be posted back when doing a Html.BeginForm() with no arguments for action or controller. So rather than change the name of the POST method I just modified the arguments to include a FormCollection. Like this: [HttpPost] public ViewResult EditBlogPost(int Id, FormCollection formCollection) { // You can then use formCollection as the IValueProvider for UpdateModel() // and TryUpdateModel() if you wish. I mean, you might as well use the // argument since you're taking it. } The formCollection variable is filled via model binding with the same content that Request.Form would be by default. You don't have to use this collection for UpdateModel() or TryUpdateModel() but I did just so I didn't feel like that collection was pointless since it really was just to make the method signature different from its GET counterpart. Thanks for the help guys!

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  • Will creating a background thread in a WCF service during a call, take up a thread in the ASP .NET t

    - by Nate Pinchot
    The following code is part of a WCF service. Will eventWatcher take up a thread in the ASP .NET thread pool, even if it is set IsBackground = true? /// <summary> /// Provides methods to work with the PhoneSystem web services SDK. /// This is a singleton since we need to keep track of what lines (extensions) are open. /// </summary> public sealed class PhoneSystemWebServiceFactory : IDisposable { // singleton instance reference private static readonly PhoneSystemWebServiceFactory instance = new PhoneSystemWebServiceFactory(); private static readonly object l = new object(); private static volatile Hashtable monitoredExtensions = new Hashtable(); private static readonly PhoneSystemWebServiceClient webServiceClient = CreateWebServiceClient(); private static volatile bool isClientRegistered; private static volatile string clientHandle; private static readonly Thread eventWatcherThread = new Thread(EventPoller) {IsBackground = true}; #region Constructor // these constructors are hacks to make the C# compiler not mark beforefieldinit // more info: http://www.yoda.arachsys.com/csharp/singleton.html static PhoneSystemWebServiceFactory() { } PhoneSystemWebServiceFactory() { } #endregion #region Properties /// <summary> /// Gets a thread safe instance of PhoneSystemWebServiceFactory /// </summary> public static PhoneSystemWebServiceFactory Instance { get { return instance; } } #endregion #region Private methods /// <summary> /// Create and configure a PhoneSystemWebServiceClient with basic http binding and endpoint from app settings. /// </summary> /// <returns>PhoneSystemWebServiceClient</returns> private static PhoneSystemWebServiceClient CreateWebServiceClient() { string url = ConfigurationManager.AppSettings["PhoneSystemWebService_Url"]; if (string.IsNullOrEmpty(url)) { throw new ConfigurationErrorsException( "The AppSetting \"PhoneSystemWebService_Url\" could not be found. Check the application configuration and ensure that the element exists. Example: <appSettings><add key=\"PhoneSystemWebService_Url\" value=\"http://xyz\" /></appSettings>"); } return new PhoneSystemWebServiceClient(new BasicHttpBinding(), new EndpointAddress(url)); } #endregion #region Event poller public static void EventPoller() { while (true) { if (Thread.CurrentThread.ThreadState == ThreadState.Aborted || Thread.CurrentThread.ThreadState == ThreadState.AbortRequested || Thread.CurrentThread.ThreadState == ThreadState.Stopped || Thread.CurrentThread.ThreadState == ThreadState.StopRequested) break; // get events //webServiceClient.GetEvents(clientHandle, 30, 100); } Thread.Sleep(5000); } #endregion #region Client registration methods private static void RegisterClientIfNeeded() { if (isClientRegistered) { return; } lock (l) { // double lock check if (isClientRegistered) { return; } //clientHandle = webServiceClient.RegisterClient("PhoneSystemWebServiceFactoryInternal", null); isClientRegistered = true; } } private static void UnregisterClient() { if (!isClientRegistered) { return; } lock (l) { // double lock check if (!isClientRegistered) { return; } //webServiceClient.UnegisterClient(clientHandle); } } #endregion #region Phone extension methods public bool SubscribeToEventsForExtension(string extension) { if (monitoredExtensions.Contains(extension)) { return false; } lock (monitoredExtensions.SyncRoot) { // double lock check if (monitoredExtensions.Contains(extension)) { return false; } RegisterClientIfNeeded(); // open line so we receive events for extension LineInfo lineInfo; try { //lineInfo = webServiceClient.OpenLine(clientHandle, extension); } catch (FaultException<PhoneSystemWebSDKErrorDetail>) { // TODO: log error return false; } // add extension to list of monitored extensions //monitoredExtensions.Add(extension, lineInfo.lineID); monitoredExtensions.Add(extension, 1); // start event poller thread if not already started if (eventWatcherThread.ThreadState == ThreadState.Stopped || eventWatcherThread.ThreadState == ThreadState.Unstarted) { eventWatcherThread.Start(); } return true; } } public bool UnsubscribeFromEventsForExtension(string extension) { if (!monitoredExtensions.Contains(extension)) { return false; } lock (monitoredExtensions.SyncRoot) { if (!monitoredExtensions.Contains(extension)) { return false; } // close line try { //webServiceClient.CloseLine(clientHandle, (int) monitoredExtensions[extension]); } catch (FaultException<PhoneSystemWebSDKErrorDetail>) { // TODO: log error return false; } // remove extension from list of monitored extensions monitoredExtensions.Remove(extension); // if we are not monitoring anything else, stop the poller and unregister the client if (monitoredExtensions.Count == 0) { eventWatcherThread.Abort(); UnregisterClient(); } return true; } } public bool IsExtensionMonitored(string extension) { lock (monitoredExtensions.SyncRoot) { return monitoredExtensions.Contains(extension); } } #endregion #region Dispose public void Dispose() { lock (l) { // close any open lines var extensions = monitoredExtensions.Keys.Cast<string>().ToList(); while (extensions.Count > 0) { UnsubscribeFromEventsForExtension(extensions[0]); extensions.RemoveAt(0); } if (!isClientRegistered) { return; } // unregister web service client UnregisterClient(); } } #endregion }

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  • Why is .NET faster than C++ in this case?

    - by acidzombie24
    -edit- I LOVE SLaks comment. "The amount of misinformation in these answers is staggering." :D Calm down guys. Pretty much all of you were wrong. I DID make optimizations. It turns out whatever optimizations I made wasn't good enough. I ran the code in GCC using gettimeofday (I'll paste code below) and used g++ -O2 file.cpp and got slightly faster results then C#. Maybe MS didn't create the optimizations needed in this specific case but after downloading and installing mingw I was tested and found the speed to be near identical. Justicle Seems to be right. I could have sworn I use clock on my PC and used that to count and found it was slower but problem solved. C++ speed isn't almost twice as slower in the MS compiler. When my friend informed me of this I couldn't believe it. So I took his code and put some timers onto it. Instead of Boo I used C#. I constantly got faster results in C#. Why? The .NET version was nearly half the time no matter what number I used. C++ version: #include <iostream> #include <stdio.h> #include <intrin.h> #include <windows.h> using namespace std; int fib(int n) { if (n < 2) return n; return fib(n - 1) + fib(n - 2); } int main() { __int64 time = 0xFFFFFFFF; while (1) { int n; //cin >> n; n = 41; if (n < 0) break; __int64 start = __rdtsc(); int res = fib(n); __int64 end = __rdtsc(); cout << res << endl; cout << (float)(end-start)/1000000<<endl; break; } return 0; } C# version: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; using System.ComponentModel; using System.Threading; using System.IO; using System.Diagnostics; namespace fibCSTest { class Program { static int fib(int n) { if (n < 2)return n; return fib(n - 1) + fib(n - 2); } static void Main(string[] args) { //var sw = new Stopwatch(); //var timer = new PAB.HiPerfTimer(); var timer = new Stopwatch(); while (true) { int n; //cin >> n; n = 41; if (n < 0) break; timer.Start(); int res = fib(n); timer.Stop(); Console.WriteLine(res); Console.WriteLine(timer.ElapsedMilliseconds); break; } } } } GCC version: #include <iostream> #include <stdio.h> #include <sys/time.h> using namespace std; int fib(int n) { if (n < 2) return n; return fib(n - 1) + fib(n - 2); } int main() { timeval start, end; while (1) { int n; //cin >> n; n = 41; if (n < 0) break; gettimeofday(&start, 0); int res = fib(n); gettimeofday(&end, 0); int sec = end.tv_sec - start.tv_sec; int usec = end.tv_usec - start.tv_usec; cout << res << endl; cout << sec << " " << usec <<endl; break; } return 0; }

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  • C++0x rvalue references - lvalues-rvalue binding

    - by Doug
    This is a follow-on question to http://stackoverflow.com/questions/2748866/c0x-rvalue-references-and-temporaries In the previous question, I asked how this code should work: void f(const std::string &); //less efficient void f(std::string &&); //more efficient void g(const char * arg) { f(arg); } It seems that the move overload should probably be called because of the implicit temporary, and this happens in GCC but not MSVC (or the EDG front-end used in MSVC's Intellisense). What about this code? void f(std::string &&); //NB: No const string & overload supplied void g1(const char * arg) { f(arg); } void g2(const std::string & arg) { f(arg); } It seems that, based on the answers to my previous question that function g1 is legal (and is accepted by GCC 4.3-4.5, but not by MSVC). However, GCC and MSVC both reject g2 because of clause 13.3.3.1.4/3, which prohibits lvalues from binding to rvalue ref arguments. I understand the rationale behind this - it is explained in N2831 "Fixing a safety problem with rvalue references". I also think that GCC is probably implementing this clause as intended by the authors of that paper, because the original patch to GCC was written by one of the authors (Doug Gregor). However, I don't this is quite intuitive. To me, (a) a const string & is conceptually closer to a string && than a const char *, and (b) the compiler could create a temporary string in g2, as if it were written like this: void g2(const std::string & arg) { f(std::string(arg)); } Indeed, sometimes the copy constructor is considered to be an implicit conversion operator. Syntactically, this is suggested by the form of a copy constructor, and the standard even mentions this specifically in clause 13.3.3.1.2/4, where the copy constructor for derived-base conversions is given a higher conversion rank than other implicit conversions: A conversion of an expression of class type to the same class type is given Exact Match rank, and a conversion of an expression of class type to a base class of that type is given Conversion rank, in spite of the fact that a copy/move constructor (i.e., a user-defined conversion function) is called for those cases. (I assume this is used when passing a derived class to a function like void h(Base), which takes a base class by value.) Motivation My motivation for asking this is something like the question asked in http://stackoverflow.com/questions/2696156/how-to-reduce-redundant-code-when-adding-new-c0x-rvalue-reference-operator-over ("How to reduce redundant code when adding new c++0x rvalue reference operator overloads"). If you have a function that accepts a number of potentially-moveable arguments, and would move them if it can (e.g. a factory function/constructor: Object create_object(string, vector<string>, string) or the like), and want to move or copy each argument as appropriate, you quickly start writing a lot of code. If the argument types are movable, then one could just write one version that accepts the arguments by value, as above. But if the arguments are (legacy) non-movable-but-swappable classes a la C++03, and you can't change them, then writing rvalue reference overloads is more efficient. So if lvalues did bind to rvalues via an implicit copy, then you could write just one overload like create_object(legacy_string &&, legacy_vector<legacy_string> &&, legacy_string &&) and it would more or less work like providing all the combinations of rvalue/lvalue reference overloads - actual arguments that were lvalues would get copied and then bound to the arguments, actual arguments that were rvalues would get directly bound. Questions My questions are then: Is this a valid interpretation of the standard? It seems that it's not the conventional or intended one, at any rate. Does it make intuitive sense? Is there a problem with this idea that I"m not seeing? It seems like you could get copies being quietly created when that's not exactly expected, but that's the status quo in places in C++03 anyway. Also, it would make some overloads viable when they're currently not, but I don't see it being a problem in practice. Is this a significant enough improvement that it would be worth making e.g. an experimental patch for GCC?

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  • c++ and c# speed compared

    - by Mack
    I was worried about C#'s speed when it deals with heavy calculations, when you need to use raw CPU power. I always thought that C++ is much faster than C# when it comes to calculations. So I did some quick tests. The first test computes prime numbers < an integer n, the second test computes some pandigital numbers. The idea for second test comes from here: Pandigital Numbers C# prime computation: using System; using System.Diagnostics; class Program { static int primes(int n) { uint i, j; int countprimes = 0; for (i = 1; i <= n; i++) { bool isprime = true; for (j = 2; j <= Math.Sqrt(i); j++) if ((i % j) == 0) { isprime = false; break; } if (isprime) countprimes++; } return countprimes; } static void Main(string[] args) { int n = int.Parse(Console.ReadLine()); Stopwatch sw = new Stopwatch(); sw.Start(); int res = primes(n); sw.Stop(); Console.WriteLine("I found {0} prime numbers between 0 and {1} in {2} msecs.", res, n, sw.ElapsedMilliseconds); Console.ReadKey(); } } C++ variant: #include <iostream> #include <ctime> int primes(unsigned long n) { unsigned long i, j; int countprimes = 0; for(i = 1; i <= n; i++) { int isprime = 1; for(j = 2; j < (i^(1/2)); j++) if(!(i%j)) { isprime = 0; break; } countprimes+= isprime; } return countprimes; } int main() { int n, res; cin>>n; unsigned int start = clock(); res = primes(n); int tprime = clock() - start; cout<<"\nI found "<<res<<" prime numbers between 1 and "<<n<<" in "<<tprime<<" msecs."; return 0; } When I ran the test trying to find primes < than 100,000, C# variant finished in 0.409 seconds and C++ variant in 5.553 seconds. When I ran them for 1,000,000 C# finished in 6.039 seconds and C++ in about 337 seconds. Pandigital test in C#: using System; using System.Diagnostics; class Program { static bool IsPandigital(int n) { int digits = 0; int count = 0; int tmp; for (; n > 0; n /= 10, ++count) { if ((tmp = digits) == (digits |= 1 << (n - ((n / 10) * 10) - 1))) return false; } return digits == (1 << count) - 1; } static void Main() { int pans = 0; Stopwatch sw = new Stopwatch(); sw.Start(); for (int i = 1; i <= 123456789; i++) { if (IsPandigital(i)) { pans++; } } sw.Stop(); Console.WriteLine("{0}pcs, {1}ms", pans, sw.ElapsedMilliseconds); Console.ReadKey(); } } Pandigital test in C++: #include <iostream> #include <ctime> using namespace std; int IsPandigital(int n) { int digits = 0; int count = 0; int tmp; for (; n > 0; n /= 10, ++count) { if ((tmp = digits) == (digits |= 1 << (n - ((n / 10) * 10) - 1))) return 0; } return digits == (1 << count) - 1; } int main() { int pans = 0; unsigned int start = clock(); for (int i = 1; i <= 123456789; i++) { if (IsPandigital(i)) { pans++; } } int ptime = clock() - start; cout<<"\nPans:"<<pans<<" time:"<<ptime; return 0; } C# variant runs in 29.906 seconds and C++ in about 36.298 seconds. I didn't touch any compiler switches and bot C# and C++ programs were compiled with debug options. Before I attempted to run the test I was worried that C# will lag well behind C++, but now it seems that there is a pretty big speed difference in C# favor. Can anybody explain this? C# is jitted and C++ is compiled native so it's normal that a C++ will be faster than a C# variant. Thanks for the answers!

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  • C++ Sentinel/Count Controlled Loop beginning programming

    - by Bryan Hendricks
    Hello all this is my first post. I'm working on a homework assignment with the following parameters. Piecework Workers are paid by the piece. Often worker who produce a greater quantity of output are paid at a higher rate. 1 - 199 pieces completed $0.50 each 200 - 399 $0.55 each (for all pieces) 400 - 599 $0.60 each 600 or more $0.65 each Input: For each worker, input the name and number of pieces completed. Name Pieces Johnny Begood 265 Sally Great 650 Sam Klutz 177 Pete Precise 400 Fannie Fantastic 399 Morrie Mellow 200 Output: Print an appropriate title and column headings. There should be one detail line for each worker, which shows the name, number of pieces, and the amount earned. Compute and print totals of the number of pieces and the dollar amount earned. Processing: For each person, compute the pay earned by multiplying the number of pieces by the appropriate price. Accumulate the total number of pieces and the total dollar amount paid. Sample Program Output: Piecework Weekly Report Name Pieces Pay Johnny Begood 265 145.75 Sally Great 650 422.50 Sam Klutz 177 88.5 Pete Precise 400 240.00 Fannie Fantastic 399 219.45 Morrie Mellow 200 110.00 Totals 2091 1226.20 You are required to code, compile, link, and run a sentinel-controlled loop program that transforms the input to the output specifications as shown in the above attachment. The input items should be entered into a text file named piecework1.dat and the ouput file stored in piecework1.out . The program filename is piecework1.cpp. Copies of these three files should be e-mailed to me in their original form. Read the name using a single variable as opposed to two different variables. To accomplish this, you must use the getline(stream, variable) function as discussed in class, except that you will replace the cin with your textfile stream variable name. Do not forget to code the compiler directive #include < string at the top of your program to acknowledge the utilization of the string variable, name . Your nested if-else statement, accumulators, count-controlled loop, should be properly designed to process the data correctly. The code below will run, but does not produce any output. I think it needs something around line 57 like a count control to stop the loop. something like (and this is just an example....which is why it is not in the code.) count = 1; while (count <=4) Can someone review the code and tell me what kind of count I need to introduce, and if there are any other changes that need to be made. Thanks. [code] //COS 502-90 //November 2, 2012 //This program uses a sentinel-controlled loop that transforms input to output. #include <iostream> #include <fstream> #include <iomanip> //output formatting #include <string> //string variables using namespace std; int main() { double pieces; //number of pieces made double rate; //amout paid per amount produced double pay; //amount earned string name; //name of worker ifstream inFile; ofstream outFile; //***********input statements**************************** inFile.open("Piecework1.txt"); //opens the input text file outFile.open("piecework1.out"); //opens the output text file outFile << setprecision(2) << showpoint; outFile << name << setw(6) << "Pieces" << setw(12) << "Pay" << endl; outFile << "_____" << setw(6) << "_____" << setw(12) << "_____" << endl; getline(inFile, name, '*'); //priming read inFile >> pieces >> pay >> rate; // ,, while (name != "End of File") //while condition test { //begining of loop pay = pieces * rate; getline(inFile, name, '*'); //get next name inFile >> pieces; //get next pieces } //end of loop inFile.close(); outFile.close(); return 0; }[/code]

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  • Odd optimization problem under MSVC

    - by Goz
    I've seen this blog: http://igoro.com/archive/gallery-of-processor-cache-effects/ The "weirdness" in part 7 is what caught my interest. My first thought was "Thats just C# being weird". Its not I wrote the following C++ code. volatile int* p = (volatile int*)_aligned_malloc( sizeof( int ) * 8, 64 ); memset( (void*)p, 0, sizeof( int ) * 8 ); double dStart = t.GetTime(); for (int i = 0; i < 200000000; i++) { //p[0]++;p[1]++;p[2]++;p[3]++; // Option 1 //p[0]++;p[2]++;p[4]++;p[6]++; // Option 2 p[0]++;p[2]++; // Option 3 } double dTime = t.GetTime() - dStart; The timing I get on my 2.4 Ghz Core 2 Quad go as follows: Option 1 = ~8 cycles per loop. Option 2 = ~4 cycles per loop. Option 3 = ~6 cycles per loop. Now This is confusing. My reasoning behind the difference comes down to the cache write latency (3 cycles) on my chip and an assumption that the cache has a 128-bit write port (This is pure guess work on my part). On that basis in Option 1: It will increment p[0] (1 cycle) then increment p[2] (1 cycle) then it has to wait 1 cycle (for cache) then p[1] (1 cycle) then wait 1 cycle (for cache) then p[3] (1 cycle). Finally 2 cycles for increment and jump (Though its usually implemented as decrement and jump). This gives a total of 8 cycles. In Option 2: It can increment p[0] and p[4] in one cycle then increment p[2] and p[6] in another cycle. Then 2 cycles for subtract and jump. No waits needed on cache. Total 4 cycles. In option 3: It can increment p[0] then has to wait 2 cycles then increment p[2] then subtract and jump. The problem is if you set case 3 to increment p[0] and p[4] it STILL takes 6 cycles (which kinda blows my 128-bit read/write port out of the water). So ... can anyone tell me what the hell is going on here? Why DOES case 3 take longer? Also I'd love to know what I've got wrong in my thinking above, as i obviously have something wrong! Any ideas would be much appreciated! :) It'd also be interesting to see how GCC or any other compiler copes with it as well! Edit: Jerry Coffin's idea gave me some thoughts. I've done some more tests (on a different machine so forgive the change in timings) with and without nops and with different counts of nops case 2 - 0.46 00401ABD jne (401AB0h) 0 nops - 0.68 00401AB7 jne (401AB0h) 1 nop - 0.61 00401AB8 jne (401AB0h) 2 nops - 0.636 00401AB9 jne (401AB0h) 3 nops - 0.632 00401ABA jne (401AB0h) 4 nops - 0.66 00401ABB jne (401AB0h) 5 nops - 0.52 00401ABC jne (401AB0h) 6 nops - 0.46 00401ABD jne (401AB0h) 7 nops - 0.46 00401ABE jne (401AB0h) 8 nops - 0.46 00401ABF jne (401AB0h) 9 nops - 0.55 00401AC0 jne (401AB0h) I've included the jump statetements so you can see that the source and destination are in one cache line. You can also see that we start to get a difference when we are 13 bytes or more apart. Until we hit 16 ... then it all goes wrong. So Jerry isn't right (though his suggestion DOES help a bit), however something IS going on. I'm more and more intrigued to try and figure out what it is now. It does appear to be more some sort of memory alignment oddity rather than some sort of instruction throughput oddity. Anyone want to explain this for an inquisitive mind? :D Edit 3: Interjay has a point on the unrolling that blows the previous edit out of the water. With an unrolled loop the performance does not improve. You need to add a nop in to make the gap between jump source and destination the same as for my good nop count above. Performance still sucks. Its interesting that I need 6 nops to improve performance though. I wonder how many nops the processor can issue per cycle? If its 3 then that account for the cache write latency ... But, if thats it, why is the latency occurring? Curiouser and curiouser ...

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  • How to make negate_unary work with any type?

    - by Chan
    Hi, Following this question: How to negate a predicate function using operator ! in C++? I want to create an operator ! can work with any functor that inherited from unary_function. I tried: template<typename T> inline std::unary_negate<T> operator !( const T& pred ) { return std::not1( pred ); } The compiler complained: Error 5 error C2955: 'std::unary_function' : use of class template requires template argument list c:\program files\microsoft visual studio 10.0\vc\include\xfunctional 223 1 Graphic Error 7 error C2451: conditional expression of type 'std::unary_negate<_Fn1>' is illegal c:\program files\microsoft visual studio 10.0\vc\include\ostream 529 1 Graphic Error 3 error C2146: syntax error : missing ',' before identifier 'argument_type' c:\program files\microsoft visual studio 10.0\vc\include\xfunctional 222 1 Graphic Error 4 error C2065: 'argument_type' : undeclared identifier c:\program files\microsoft visual studio 10.0\vc\include\xfunctional 222 1 Graphic Error 2 error C2039: 'argument_type' : is not a member of 'std::basic_ostream<_Elem,_Traits>::sentry' c:\program files\microsoft visual studio 10.0\vc\include\xfunctional 222 1 Graphic Error 6 error C2039: 'argument_type' : is not a member of 'std::basic_ostream<_Elem,_Traits>::sentry' c:\program files\microsoft visual studio 10.0\vc\include\xfunctional 230 1 Graphic Any idea? Update Follow "templatetypedef" solution, I got new error: Error 3 error C2831: 'operator !' cannot have default parameters c:\visual studio 2010 projects\graphic\graphic\main.cpp 39 1 Graphic Error 2 error C2808: unary 'operator !' has too many formal parameters c:\visual studio 2010 projects\graphic\graphic\main.cpp 39 1 Graphic Error 4 error C2675: unary '!' : 'is_prime' does not define this operator or a conversion to a type acceptable to the predefined operator c:\visual studio 2010 projects\graphic\graphic\main.cpp 52 1 Graphic Update 1 Complete code: #include <iostream> #include <functional> #include <utility> #include <cmath> #include <algorithm> #include <iterator> #include <string> #include <boost/assign.hpp> #include <boost/assign/std/vector.hpp> #include <boost/assign/std/map.hpp> #include <boost/assign/std/set.hpp> #include <boost/assign/std/list.hpp> #include <boost/assign/std/stack.hpp> #include <boost/assign/std/deque.hpp> struct is_prime : std::unary_function<int, bool> { bool operator()( int n ) const { if( n < 2 ) return 0; if( n == 2 || n == 3 ) return 1; if( n % 2 == 0 || n % 3 == 0 ) return 0; int upper_bound = std::sqrt( static_cast<double>( n ) ); for( int pf = 5, step = 2; pf <= upper_bound; ) { if( n % pf == 0 ) return 0; pf += step; step = 6 - step; } return 1; } }; /* template<typename T> inline std::unary_negate<T> operator !( const T& pred, typename T::argument_type* dummy = 0 ) { return std::not1<T>( pred ); } */ inline std::unary_negate<is_prime> operator !( const is_prime& pred ) { return std::not1( pred ); } template<typename T> inline void print_con( const T& con, const std::string& ms = "", const std::string& sep = ", " ) { std::cout << ms << '\n'; std::copy( con.begin(), con.end(), std::ostream_iterator<typename T::value_type>( std::cout, sep.c_str() ) ); std::cout << "\n\n"; } int main() { using namespace boost::assign; std::vector<int> nums; nums += 1, 3, 5, 7, 9; nums.erase( remove_if( nums.begin(), nums.end(), !is_prime() ), nums.end() ); print_con( nums, "After remove all primes" ); } Thanks, Chan Nguyen

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  • Designing an API with compile-time option to remove first parameter to most functions and use a glob

    - by tomlogic
    I'm trying to design a portable API in ANSI C89/ISO C90 to access a wireless networking device on a serial interface. The library will have multiple network layers, and various versions need to run on embedded devices as small as an 8-bit micro with 32K of code and 2K of data, on up to embedded devices with a megabyte or more of code and data. In most cases, the target processor will have a single network interface and I'll want to use a single global structure with all state information for that device. I don't want to pass a pointer to that structure through the network layers. In a few cases (e.g., device with more resources that needs to live on two networks) I will interface to multiple devices, each with their own global state, and will need to pass a pointer to that state (or an index to a state array) through the layers. I came up with two possible solutions, but neither one is particularly pretty. Keep in mind that the full driver will potentially be 20,000 lines or more, cover multiple files, and contain hundreds of functions. The first solution requires a macro that discards the first parameter for every function that needs to access the global state: // network.h typedef struct dev_t { int var; long othervar; char name[20]; } dev_t; #ifdef IF_MULTI #define foo_function( x, a, b, c) _foo_function( x, a, b, c) #define bar_function( x) _bar_function( x) #else extern dev_t DEV; #define IFACE (&DEV) #define foo_function( x, a, b, c) _foo_function( a, b, c) #define bar_function( x) _bar_function( ) #endif int bar_function( dev_t *IFACE); int foo_function( dev_t *IFACE, int a, long b, char *c); // network.c #ifndef IF_MULTI dev_t DEV; #endif int bar_function( dev_t *IFACE) { memset( IFACE, 0, sizeof *IFACE); return 0; } int foo_function( dev_t *IFACE, int a, long b, char *c) { bar_function( IFACE); IFACE->var = a; IFACE->othervar = b; strcpy( IFACE->name, c); return 0; } The second solution defines macros to use in the function declarations: // network.h typedef struct dev_t { int var; long othervar; char name[20]; } dev_t; #ifdef IF_MULTI #define DEV_PARAM_ONLY dev_t *IFACE #define DEV_PARAM DEV_PARAM_ONLY, #else extern dev_t DEV; #define IFACE (&DEV) #define DEV_PARAM_ONLY void #define DEV_PARAM #endif int bar_function( DEV_PARAM_ONLY); // I don't like the missing comma between DEV_PARAM and arg2... int foo_function( DEV_PARAM int a, long b, char *c); // network.c #ifndef IF_MULTI dev_t DEV; #endif int bar_function( DEV_PARAM_ONLY) { memset( IFACE, 0, sizeof *IFACE); return 0; } int foo_function( DEV_PARAM int a, long b, char *c) { bar_function( IFACE); IFACE->var = a; IFACE->othervar = b; strcpy( IFACE->name, c); return 0; } The C code to access either method remains the same: // multi.c - example of multiple interfaces #define IF_MULTI #include "network.h" dev_t if0, if1; int main() { foo_function( &if0, -1, 3.1415926, "public"); foo_function( &if1, 42, 3.1415926, "private"); return 0; } // single.c - example of a single interface #include "network.h" int main() { foo_function( 11, 1.0, "network"); return 0; } Is there a cleaner method that I haven't figured out? I lean toward the second since it should be easier to maintain, and it's clearer that there's some macro magic in the parameters to the function. Also, the first method requires prefixing the function names with "_" when I want to use them as function pointers. I really do want to remove the parameter in the "single interface" case to eliminate unnecessary code to push the parameter onto the stack, and to allow the function to access the first "real" parameter in a register instead of loading it from the stack. And, if at all possible, I don't want to have to maintain two separate codebases. Thoughts? Ideas? Examples of something similar in existing code? (Note that using C++ isn't an option, since some of the planned targets don't have a C++ compiler available.)

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  • Linked lists in Java - Help with writing methods

    - by user368241
    Representation of a string in linked lists In every intersection in the list there will be 3 fields : The letter itself. The number of times it appears consecutively. A pointer to the next intersection in the list. The following class CharNode represents a intersection in the list : public class CharNode { private char _data; private int _value; private charNode _next; public CharNode (char c, int val, charNode n) { _data = c; _value = val; _next = n; } public charNode getNext() { return _next; } public void setNext (charNode node) { _next = node; } public int getValue() { return _value; } public void setValue (int v) { value = v; } public char getData() { return _data; } public void setData (char c) { _data = c; } } The class StringList represents the whole list : public class StringList { private charNode _head; public StringList() { _head = null; } public StringList (CharNode node) { _head = node; } } Add methods to the class StringList according to the details : (I will add methods gradually according to my specific questions) (Pay attention, these are methods from the class String and we want to fulfill them by the representation of a string by a list as explained above) Pay attention to all the possible error cases. Write what is the time complexity and space complexity of every method that you wrote. Make sure the methods you wrote are effective. It is NOT allowed to use ready classes of Java. It is NOT allowed to move to string and use string operations. 1) public int indexOf (int ch) - returns the index in the string it is operated on of the first appeareance of the char "ch". If the char "ch" doesn't appear in the string, returns -1. If the value of fromIndex isn't in the range, returns -1. Here is my try : public int indexOf (int ch) { int count = 0; charNode pos = _head; if (pos == null ) { return -1; } for (pos = _head; pos!=null && pos.getData()!=ch; pos = pos.getNext()) { count = count + pos.getValue(); } if (pos==null) return -1; return count; } Time complexity = O(N) Space complexity = O(1) EDIT : I have a problem. I tested it in BlueJ and if the char ch doesn't appear it returns -1 but if it does, it always returns 0 and I don't understand why... I am confused. How can the compiler know that the value is the number of times the letter appears consecutively? Can I assume this because its given on the question or what? If it's true and I can assume this, then my code should be correct right? Ok I just spoke with my instructor and she said it isn't required to write it in the exercise but in order for me to test that it indeed works, I need to open a new class and write a code for making a list so that the the value of every node is the number of times the letter appears consecutively. Can someone please assist me? So I will copy+paste to BlueJ and this way I will be able to test all the methods. Meanwhile I am moving on to the next methods. 2) public int indexOf (int ch, int fromIndex) - returns the index in the string it is operated on of the first appeareance of the char "ch", as the search begins in the index "fromIndex". If the char "ch" doesn't appear in the string, returns -1. If the value of fromIndex doesn't appear in the range, returns -1. Here is my try: public int indexOf (int ch, int fromIndex) { int count = 0, len=0, i; charNode pos = _head; CharNode cur = _head; for (pos = _head; pos!=null; pos = pos.getNext()) { len = len+1; } if (fromIndex<0 || fromIndex>=len) return -1; for (i=0; i<fromIndex; i++) { cur = cur.getNext(); } if (cur == null ) { return -1; } for (cur = _head; cur!=null && cur.getData()!=ch; cur = cur.getNext()) { count = count + cur.getValue(); } if (cur==null) return -1; return count; } Time complexity = O(N) ? Space complexity = O(1) 3) public StringList concat (String str) - returns a string that consists of the string that it is operated on and in its end the string "str" is concatenated. Here is my try : public StringList concat (String str) { String str = ""; charNode pos = _head; if (str == null) return -1; for (pos = _head; pos!=null; pos = pos.getNext()) { str = str + pos.getData(); } str = str + "str"; return str; } Time complexity = O(N) Space complexity = O(1)

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  • what is mistakes/errors in this code c++ tell me the correction ??

    - by jeje
    hello all here in this code the compiler print error : 132 C:.... `createlist' undeclared (first use this function) (Each undeclared identifier is reported only once for each function it appears in.) and repeat it again in all calls in main function :( what's the problem ?? plzzzz help me #include<iostream> #include<string> using namespace std; template <typename T> struct Node { T num; struct Node<T> *next; // to craet list nodes void createlist(Node<T> *p) { T data; for( ; ; ) // its containue until user want to stop { cout<<"enter data number or '#' to stop\n"; cin>>data; if(data == '#') { p->next =NULL; break; } else { p->num= data; p->next = new Node<T>; p=p->next; } } } //count list to use it in sort function int countlist (Node<T> *p) { int count=0; while(p->next != NULL) { count++; p=p->next; } return count; } // sort list void sort( Node<T> *p) { Node<T> *p1, *p2; //element 1 & 2 to compare between them int i, j , n; T temp; n= countlist(p); for( i=1; i<n ; i++) { // here every loop time we put the first element in list in p1 and the second in p2 p1=p; p2=p->next; for(j=1; j<=(n-i) ; j++) { if( p1->num > p2->num) { temp=p2->num; p2->num=p1->num; p1->num=temp; } } p1= p1->next; p2= p2->next; } } //add new number in any location the user choose void insertatloc(Node<T> *p) { T n; //read new num int loc; //read the choosen location Node<T> *locadd, *newnum, *temp; cout <<" enter location you want ..! \n"; cin>>loc; locadd=NULL; //make it null to checked if there is location after read it from user ot not while(p->next !=NULL) { if( p->next==loc) { locadd=p; break; } p=p->next; } if (locadd==NULL) {cout<<" cannot find the location\n";} else //if location is right {cout<<" enter new number\n"; // new number to creat also new location for it cin>>n; newnum= new Node/*<T>*/; newnum->num=n; temp= locadd->next; locadd->next=newnum; newnum->next=temp; } locadd->num=sort(locadd); // call sort function } // display all list nodes void displaylist (Node<T> *p) { while (p->next != NULL) { cout<<" the list contain:\n"; cout<<p->num<<endl; p=p->next; } } };//end streuct int main() { cout<<"*** Welcome in Linked List Sheet 2****\n"; // defined pointer for structer Node // that value is the address of first node struct Node<int>*mynodes= new struct Node<int>; // create nodes in mynodes list cout<<"\nCreate nodes in list"; createlist(mynodes); // insert node in location insertatloc(mynodes); /* count the number of all nodes nodescount = countlist(mynodes); cout<<"\nThe number of nodes in list is: "<<nodescount;*/ // sort nodes in list sort(mynodes); // Display nodes cout<<"\nDisplay all nodes in list:\n"; displaylist(mynodes); system("pause"); return 0; }

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