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  • java reflection

    - by user622222
    Hi all, System.out.println("Class name : "); BufferedReader reader= new BufferedReader(new InputStreamReader(System.in)); String line = reader.readLine(); Class<?> writeoutClass = Class.forName(line); Method Writeout = null; for (Method mth : writeoutClass.getDeclaredMethods()) { if (mth.getName().startsWith("Writeout")) { Writeout = mth; break; } It's giving error like that; java.lang.ClassNotFoundException: a How can i generate that class?

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  • Zend Framework Handle One to Many

    - by user192344
    I have 2 tables "user", "contact", the relation between two tables is one user has many contact Table member m_id name ------------ Table Contact c_id c_m_id value in zend model class, i do it in this way /* Member.php */ class Default_Model_DbTable_Member extends Zend_Db_Table_Abstract { protected $_name = 'member'; protected $_dependentTables = array('Default_Model_DbTable_Contact'); } /* Contact.php */ class Default_Model_DbTable_Contact extends Zend_Db_Table_Abstract { protected $_name = 'contact'; protected $_referenceMap = array( 'Member' => array( 'columns'=> array('c_id'), 'refTableClass'=> 'Default_Model_DbTable_Member', 'refColumns'=> array('c_m_id') ) ); /* IndexController.php */ class IndexController extends Zend_Controller_Action { public function indexAction() { $m= new Default_Model_DbTable_Member(); $row = $m->find(1); $data = $row->current(); $data = $data->findDependentRowset('Default_Model_DbTable_Contact'); print_r($data->toArray()); } } But i just get Invalid parameter number: no parameters were bound , my goal is to search a member detail record, and it also contains a array which store all contact info (i can use join method to do that, but i just want to try zend feature)

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  • Speed comparison - Template specialization vs. Virtual Function vs. If-Statement

    - by Person
    Just to get it out of the way... Premature optimization is the root of all evil Make use of OOP etc. I understand. Just looking for some advice regarding the speed of certain operations that I can store in my grey matter for future reference. Say you have an Animation class. An animation can be looped (plays over and over) or not looped (plays once), it may have unique frame times or not, etc. Let's say there are 3 of these "either or" attributes. Note that any method of the Animation class will at most check for one of these (i.e. this isn't a case of a giant branch of if-elseif). Here are some options. 1) Give it boolean members for the attributes given above, and use an if statement to check against them when playing the animation to perform the appropriate action. Problem: Conditional checked every single time the animation is played. 2) Make a base animation class, and derive other animations classes such as LoopedAnimation and AnimationUniqueFrames, etc. Problem: Vtable check upon every call to play the animation given that you have something like a vector<Animation>. Also, making a separate class for all of the possible combinations seems code bloaty. 3) Use template specialization, and specialize those functions that depend on those attributes. Like template<bool looped, bool uniqueFrameTimes> class Animation. Problem: The problem with this is that you couldn't just have a vector<Animation> for something's animations. Could also be bloaty. I'm wondering what kind of speed each of these options offer? I'm particularly interested in the 1st and 2nd option because the 3rd doesn't allow one to iterate through a general container of Animations. In short, what is faster - a vtable fetch or a conditional?

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  • in vb.net an error is coming

    - by user275111
    Compiler Error Message: ASPNET: Make sure that the class defined in this code file matches the 'inherits' attribute, and that it extends the correct base class (e.g. Page or UserControl). in vb code-i used namespace and a class.

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  • Using an empty column as a divider in a JTable.

    - by Catalina Island
    I'm trying to use an empty column as a divider between pairs of columns in a JTable. Here's a picture and code for what I have so far. I know I can change the look using a custom TableCellRenderer. Before I go down that road, is there a better way to do this? Any ideas appreciated. import javax.swing.*; import javax.swing.table.*; public class TablePanel extends JPanel { public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { JFrame f = new JFrame("TablePanel"); f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); f.add(new TablePanel()); f.pack(); f.setVisible(true); } }); } public TablePanel() { TableModel dataModel = new MyModel(); JTable table = new JTable(dataModel); table.getColumnModel().getColumn(MyModel.DIVIDER).setMaxWidth(0); JScrollPane jsp = new JScrollPane(table); jsp.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); this.add(jsp); } private static class MyModel extends AbstractTableModel { private static final int DIVIDER = 2; private final String[] names = { "A1", "A2", "", "B1", "B2" }; @Override public int getRowCount() { return 32; } @Override public int getColumnCount() { return names.length; } @Override public String getColumnName(int col) { if (col == DIVIDER) return ""; return names[col]; } @Override public Object getValueAt(int row, int col) { if (col == DIVIDER) return ""; return (row + 1) / 10.0; } @Override public Class<?> getColumnClass(int col) { if (col == DIVIDER) return String.class; return Number.class; } } }

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  • How to use JNI, but only when available for current platform?

    - by Mecki
    What is the common way (or best practice) to optionally use JNI? E.g. I have a Java class and this class is 100% pure Java, so it can run on all platforms. However, on some platforms I'd like to speed up some heavy calculations using JNI - which works fine. Unfortunately I cannot support any existing Java platform in the world. So I guess it is fine to initially only support the big three: Linux, Windows, Mac OS X. So what I'd like to do is to use JNI on those three platforms and use the 100% pure Java version on all other platforms. Now I can think of various ways how to do that (loading class dynamically for example and either loading the JNI class or the pure Java one), but thinking that this is a common issue that thousands of projects had to solve in the past for sure, I'm really surprised to not find any documentation or references to the question how to solve this most elegantly or effectively.

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  • Grails Unique Constraint for Groups

    - by WaZ
    Hi there, I have the following requirement I have 3 domains namely: class Product { String productName static constraints = { productName(unique:true,blank:false) } class SubType { String subTypeName static constraints = { subTypeName(unique:true,blank:false) } String toString() { "${subTypeName}" } } class CLType { String TypeName static belongsTo = Car static hasMany = [car:Cars] static constraints = { } String toString() { "${TypeName}" } class CLines implements Serializable { Dealer dealer CLType clType SubType subType Product product static constraints = { dealer(nullable:false,blank:false,unique:['subType','product','clType']) clType(blank:false,nullable:false) subType(nullable:true) product(nullable:true) } } I want to achieve this combination: A user can assign dealer a CLType. But cannot have duplicates. As an example consider this scenario Please let me know what to mention in my unqiue constraint to make this possible? Thanks, Much Appreciated.

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  • Django: How can I add weight/ordering to a many to many relationship?

    - by Klaas van Schelven
    I'm having Pages with TextBlocks on them. Text Blocks may appear on different pages, pages may have several text blocks on them. Every page may have these blocks in an ordering of it's own. This can be solved by using a separate through parameter. Like so: class TextBlock(models.Model): title = models.CharField(max_length=255) text = models.TextField() class Page(models.Model): textblocks = models.ManyToManyField(TextBlock, through=OrderedTextBlock) class OrderedTextBlock(models.Model): text_block = models.ForeignKey(TextBlock) product_page = models.ForeignKey(ProductPage) weight = models.IntegerField() class Meta: ordering = ('weight',) But I'm not very enthousiastic about the violations of DRY for my app. (There's a lot of ordered ManyToMany relations). Is there a recommended way to go about this?

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  • How can I disable a model field in a django form

    - by jammon
    I have a model like this: class MyModel(models.Model): REGULAR = 1 PREMIUM = 2 STATUS_CHOICES = ((REGULAR, "regular"), (PREMIUM, "premium")) name = models.CharField(max_length=30) status = models.IntegerField(choices = STATUS_CHOICES, default = REGULAR) class MyForm(forms.ModelForm): class Meta: model = models.MyModel In a view I initialize one field and try to make it non-editable: myform = MyForm(initial = {'status': requested_status}) myform.fields['status'].editable = False But the user can still change that field. What's the real way to accomplish what I'm after?

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  • Getting list of fields back from 'use fields' pragma?

    - by makenai
    So I'm familiar with the use fields pragma in Perl that can be used to restrict the fields that are stored in a class: package Fruit; use fields qw( color shape taste ); sub new { my ( $class, $params ) = @_; my $self = fields::new( $class ) unless ref $class; foreach my $name ( keys %$params ) { $self->{ $name } = $params->{ $name }; } return $self; } My question is.. once I've declared the fields at the top, how I can get the list back.. say because I want to generate accessors dynamically? Is keys %FIELDS the only way? Secondarily, is there a more efficient way to pre-populate the fields in the constructor than looping through and assigning each parameter as I am above? Thanks!

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  • Is there an efficient way to write this PHP if / else statement?

    - by nvoyageur
    I've written a simple issue tracker for my web app. I have some comments that I want to keep private (only a role of 'root' can see them). Is there a better way to write the following so I do not need the empty else section? $role will be 'root' or some other values $is_private will be true if the comment is private <?php // Don't show private comments to non-root users if ($is_private && 'root' != $role): // NON Root cannot see private else: ?> <div class="comment <?= $is_private ? 'private' : '' ; ?>"> <div class="comment-meta toolbar"> <?= $is_private ? 'PRIVATE - ': ''; ?> <span class="datestamp"><?= $created_at; ?></span> - <span class="fullname"><?= $fname . ' ' . $lname; ?></span></div> <p class="content"><?= nl2br($body); ?></p> </div> <?php endif; ?>

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  • PHP5: restrict access to function to certain classes

    - by Tim
    Is there a way in PHP5 to only allow a certain class or set of classes to call a particular function? For example, let's say I have three classes ("Foo", "Bar", and "Baz"), all with similarly-named methods, and I want Bar to be able to call Foo::foo() but deny Baz the ability to make that call: class Foo { static function foo() { print "foo"; } } class Bar { static function bar() { Foo::foo(); print "bar"; } // Should work } class Baz { static function baz() { Foo::foo; print "baz"; } // Should fail } Foo::foo(); // Should also fail There's not necessarily inheritance between Foo, Bar, and Baz, so the use of protected or similar modifiers won't help; however, the methods aren't necessarily static (I made them so here for the simplicity of the example).

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  • Find the right value in recursive array

    - by fire
    I have an array with multiple sub-arrays like this: Array ( [0] => Array ( [Page_ID] => 1 [Page_Parent_ID] => 0 [Page_Title] => Overview [Page_URL] => overview [Page_Type] => content [Page_Order] => 1 ) [1] => Array ( [0] => Array ( [Page_ID] => 2 [Page_Parent_ID] => 1 [Page_Title] => Team [Page_URL] => overview/team [Page_Type] => content [Page_Order] => 1 ) ) [2] => Array ( [Page_ID] => 3 [Page_Parent_ID] => 0 [Page_Title] => Funds [Page_URL] => funds [Page_Type] => content [Page_Order] => 2 ) [3] => Array ( [0] => Array ( [Page_ID] => 4 [Page_Parent_ID] => 3 [Page_Title] => Strategy [Page_URL] => funds/strategy [Page_Type] => content [Page_Order] => 1 ) [1] => Array ( [0] => Array ( [Page_ID] => 7 [Page_Parent_ID] => 4 [Page_Title] => A Class Fund [Page_URL] => funds/strategy/a-class-fund [Page_Type] => content [Page_Order] => 1 ) [1] => Array ( [0] => Array ( [Page_ID] => 10 [Page_Parent_ID] => 7 [Page_Title] => Information [Page_URL] => funds/strategy/a-class-fund/information [Page_Type] => content [Page_Order] => 1 ) [1] => Array ( [Page_ID] => 11 [Page_Parent_ID] => 7 [Page_Title] => Fund Data [Page_URL] => funds/strategy/a-class-fund/fund-data [Page_Type] => content [Page_Order] => 2 ) ) [2] => Array ( [Page_ID] => 8 [Page_Parent_ID] => 4 [Page_Title] => B Class Fund [Page_URL] => funds/strategy/b-class-fund [Page_Type] => content [Page_Order] => 2 ) I need a function to find the right Page_URL so if you know the $url is "funds/strategy/a-class-fund" I need to pass that to a function that returns a single array result (which would be the Page_ID = 7 array in this example). Having a bit of a stupid day, any help would be appreciated!

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  • Purpose of singletons in programming

    - by thecoshman
    This is admittedly a rather loose question. My current understanding of singletons is that they are a class that you set up in such a way that only one instance is ever created. This sounds a lot like a static class to me. The main differnce being that with a static class you don't / can't instance it, you just use it such as Math.pi(). With a singletong class, you would still need to do something like singleton mySingleton = new singleton(); mysingleton.set_name("foo"); singleton otherSingleton = new singleton(); // correct me if i am wrong, but mysingleton == othersingleton right now, yes? // this the following should happen? otherSingleston.set_name("bar"); mysingleton.report_name(); // will output "bar" won't it? Please note, I am asking this language independently, more about the concept. So I am not so worried about actually how to coed such a class, but more why you would wan't to and what thing you would need to consider.

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  • Dynamic, reflective SignalHandler in Java

    - by pilcrow
    How do I install signal handling logic iff sun.misc.Signal is available? Background First generation of my code looked something like this: class MyApp { public static void main(String[] args) { ... Signal.handle(term_sig, new SignalHandler() { public void handle(Signal sig) { ... } }); ... } } I believe I understand how to reflectively test for and use signal handlers -- Class.forName("sun.misc.Signal"), reflectively call Signal.handle, and so forth. My impulse was simply to instantiate another anonymous inner class with the dynamically obtained SignalHandler class, but I think that's just wishful syntax.

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  • How do I differentiate between different descendents with the same name?

    - by zotty
    I've got some XML I'm trying to import with c#, which looks something like this: <run> <name = "bob"/> <date = "1958"/> </run> <run> <name = "alice"/> <date = "1969"/> </run> I load my xml using XElement xDoc=XElement.Load(filename); What I want to do is have a class for "run", under which I can store names and dates: public class RunDetails { public RunDetails(XElement xDoc, XNamespace xmlns) { var query = from c in xDoc.Descendants(xmlns + "run").Descendants(xmlns + "name") select c; int i=0; foreach (XElement a in query) { this.name= new NameStr(a, xmlns); // a class for names Name.Add(this.name); //Name is a List<NameStr> i++; } // Here, i=2, but what I want is a new instance of the RunDetails class for each <run> } } How can I set up my code to create a new instance of the RunDetails class for every < run, and to only select the < name and < date inside a given < run?

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  • How do I set up Array/List dependencies in code with Castle Windsor?

    - by SharePoint Newbie
    Hi, I have the following classes: class Repository : IRepository class ReadOnlyRepository : Repository abstract class Command abstract CommandImpl : Command { public CommandImpl(Repository repository){} } class Service { public Service (Command[] commands){} } I register them in code as follows: var container = new Container("WindsorCOntainer.config"); var container = new WindsorContainer(new XmlInterpreter("WindsorConfig.xml")); container.Kernel.Resolver.AddSubResolver(new ArrayResolver(container.Kernel)); container.AddComponent("repository", typeof(RentServiceRepository)); container.Resolve<RentServiceRepository>(); container.AddComponent("command", typeof(COmmandImpl)); container.AddComponent("rentService", typeof (RentService)); container.Resolve<RentService>(); // Fails here I get the message that "RentService is waiting for dependency commands" What am I doing wrong? Thanks,

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  • jQuery show/hide for FAQ using the next() function

    - by jon_brockman
    Maybe it's because it's Friday but I'm stuck on a simple problem. I'm building a FAQ page where a user clicks on a question, revealing the answer beneath it. I'm trying to get the next() function to just grab the next instance of an "answer" div but, despite not getting any JS errors, the hidden div isn't showing. Here's the code: .answer { display:none; } $("a.question").click(function(){ $(this).next(".answer").toggle(); }); <a href="#" class="question">Queston 1</a> <div class="answer">Answer 1</div> <a href="#" class="question">Queston 2</a> <div class="answer">Answer 2</div>

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  • How do I avoid a race condition in my Rails app?

    - by Cathal
    Hi, I have a really simple Rails application that allows users to register their attendance on a set of courses. The ActiveRecord models are as follows: class Course < ActiveRecord::Base has_many :scheduled_runs ... end class ScheduledRun < ActiveRecord::Base belongs_to :course has_many :attendances has_many :attendees, :through => :attendances ... end class Attendance < ActiveRecord::Base belongs_to :user belongs_to :scheduled_run, :counter_cache => true ... end class User < ActiveRecord::Base has_many :attendances has_many :registered_courses, :through => :attendances, :source => :scheduled_run end A ScheduledRun instance has a finite number of places available, and once the limit is reached, no more attendances can be accepted. def full? attendances_count == capacity end attendances_count is a counter cache column holding the number of attendance associations created for a particular ScheduledRun record. My problem is that I don't fully know the correct way to ensure that a race condition doesn't occur when 1 or more people attempt to register for the last available place on a course at the same time. My Attendance controller looks like this: class AttendancesController < ApplicationController before_filter :load_scheduled_run before_filter :load_user, :only => :create def new @user = User.new end def create unless @user.valid? render :action => 'new' end @attendance = @user.attendances.build(:scheduled_run_id => params[:scheduled_run_id]) if @attendance.save flash[:notice] = "Successfully created attendance." redirect_to root_url else render :action => 'new' end end protected def load_scheduled_run @run = ScheduledRun.find(params[:scheduled_run_id]) end def load_user @user = User.create_new_or_load_existing(params[:user]) end end As you can see, it doesn't take into account where the ScheduledRun instance has already reached capacity. Any help on this would be greatly appreciated.

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  • how does serializable work in java?

    - by Karl Trumstedt
    If I have an instance of a class that I store in a session I need to make it serializable. This class has a static variable, will this be serialized in every instance stored? The static variable is a reference to a cache containing a lot of data in the background. Will all of this data be serialized? If so, it seems preferable to make this variable transient and re-fetch the cache instance each time the instance is restored. Maybe not store the cache instance at all in the class. Will the constructor execute when a class is restored from a serialized state? if not is there any other method I can use to re-instate a transient variable?

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  • help me to choose between two designs

    - by alex
    // stupid title, but I could not think anything smarter I have a code (see below, sorry for long code but it's very-very simple): namespace Option1 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public AuxClass1 AuxClass { get { return _auxClass; } set { _auxClass = value; } } public MainClass() { _auxClass = new AuxClass1(); } } } namespace Option2 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public string Field1 { get { return _auxClass.Field1; } set { _auxClass.Field1 = value; } } public void Method1() { _auxClass.Method1(); } public void Method2() { _auxClass.Method2(); } public MainClass() { _auxClass = new AuxClass1(); } } } class Program { static void Main(string[] args) { // Option1 Option1.MainClass mainClass1 = new Option1.MainClass(); mainClass1.AuxClass.Field1 = "string1"; mainClass1.AuxClass.Method1(); mainClass1.AuxClass.Method2(); // Option2 Option2.MainClass mainClass2 = new Option2.MainClass(); mainClass2.Field1 = "string2"; mainClass2.Method1(); mainClass2.Method2(); Console.ReadKey(); } } What option (option1 or option2) do you prefer ? In which cases should I use option1 or option2 ? Is there any special name for option1 or option2 (composition, aggregation) ?

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  • C++: inheritance problem

    - by Helltone
    It's quite hard to explain what I'm trying to do, I'll try: Imagine a base class A which contains some variables, and a set of classes deriving from A which all implement some method bool test() that operates on the variables inherited from A. class A { protected: int somevar; // ... }; class B : public A { public: bool test() { return (somevar == 42); } }; class C : public A { public: bool test() { return (somevar > 23); } }; // ... more classes deriving from A Now I have an instance of class A and I have set the value of somevar. int main(int, char* []) { A a; a.somevar = 42; Now, I need some kind of container that allows me to iterate over the elements i of this container, calling i::test() in the context of a... that is: std::vector<...> vec; // push B and C into vec, this is pseudo-code vec.push_back(&B); vec.push_back(&C); bool ret = true; for(i = vec.begin(); i != vec.end(); ++i) { // call B::test(), C::test(), setting *this to a ret &= ( a .* (&(*i)::test) )(); } return ret; } How can I do this? I've tried two methods: forcing a cast from B::* to A::*, adapting a pointer to call a method of a type on an object of a different type (works, but seems to be bad); using std::bind + the solution above, ugly hack; changing the signature of bool test() so that it takes an argument of type const A& instead of inheriting from A, I don't really like this solution because somevar must be public.

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  • What would be a better implementation of shared variable among subclass

    - by Churk
    So currently I have a spring unit testing application. And it requires me to get a session cookie from a foreign authentication source. Problem what that is, this authentication process is fairly expensive and time consuming, and I am trying to create a structure where I am authenticate once, by any subclass, and any subsequent subclass is created, it will reuse this session cookie without hitting the authentication process again. My problem right now is, the static cookie is null each time another subclass is created. And I been reading that using static as a global variable is a bad idea, but I couldn't think of another way to do this because of Spring framework setting things during run time and how I would set the cookie so that all other classes can use it. Another piece of information. The variable is being use, but is change able during run time. It is not a single user being signed in and used across the board. But more like a Sub1 would call login, and we have a cookie. Then multiple test will be using that login until SubX will come in and say, I am using different credential, so I need to login as something else. And repeats. Here is a outline of my code: public class Parent implements InitializingBean { protected static String BASE_URL; public static Cookie cookie; ... All default InitializingBean methods ... afterPropertiesSet() { cookie = // login process returns a cookie } } public class Sub1 extends Parent { @resource public String baseURL; @PostConstruct public void init() { // set parents with my baseURL; BASE_URL = baseURL; } public void doSomething() { // Do something with cookie, because it should have been set by parent class } } public class Sub2 extends Parent { @resource public String baseURL; @PostConstruct public void init() { // set parents with my baseURL; BASE_URL = baseURL; } public void doSomethingElse() { // Do something with cookie, because it should have been set by parent class } }

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  • Java: Reflection against casting when you know superclass

    - by Ema
    I don't know exactly how to define my doubt so please be patient if the question has already been asked. Let's say I have to dinamically instantiate an object. This object will surely be instance of a subclass of a known, immutable class A. I can obtain dinamically the specific implementation class. Would it be better to use reflection exactly as if I didn't know anything about the target class, or would it be preferrable/possible to do something like: A obj = (Class.forName("com.package.Sub-A")) new A(); where Sub-A extends A ? The purpose would be to avoid reflection overhead times... Thank you in advance.

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  • Undefined behaviour with non-virtual destructors - is it a real-world issue?

    - by Roddy
    Consider the following code: class A { public: A() {} ~A() {} }; class B: public A { B() {} ~B() {} }; A* b = new B; delete b; // undefined behaviour My understanding is that the C++ standard says that deleting b is undefined behaviour - ie, anything could happen. But, in the real world, my experience is that ~A() is always invoked, and the memory is correctly freed. if B introduces any class members with their own destructors, they won't get invoked, but I'm only interested in the simple kind of case above, where inheritance is used maybe to fix a bug in one class method for which source code is unavailable. Obviously this isn't going to be what you want in non-trivial cases, but it is at least consistent. Are you aware of any C++ implementation where the above does NOT happen, for the code shown?

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