instantiation

Given a class, I would like to limit the number of objects created from this class to a given number, say 4. Is there a method to achieve this? The basic idea is to count the number of created instances in some static variable. I would implement it like this. Simpler approaches exist, but this one has some advantages. template<class T, int maxInstances> class Counter { protected: Counter() { if( ++noInstances() > maxInstances ) { throw logic_error( "Cannot create another instance" ); } } int& noInstances() { static int noInstances = 0; return noInstances; } /* this can be uncommented to

I am confused about the point of instantiation with the following example: #include <iostream> void f(int){std::cout<<"int"<<std::endl;}//3 template <typename T> void g(T t) { f(t);//4 } void f(double){std::cout<<"double"<<std::endl;} int main() { g<int>(1);//1.point of instantiation for g<int> g<double>(1.1);//2.point of instantiation for g<double>, so f(double) is visible from here? return 0; } I though f is a dependent name and 1. is the point of instantiation for g< int > and 2. is the point of instantiation for g< double >, so f(double) is visible for g(1.1), however the output is int int

I'm working on Java Swing application with Google Guice as an IOC container. Things are working pretty well. There are some UI problems. When a standard L&F is replaced with Pushing pixels Substance L&F application is not running due to Guice's Swing components creation outside of UI thread. Is there a way to tell Guice to create Swing components in the UI thread? Maybe I should create custom providers which will return Swing components after SwingUtilities.invokeAndWait(Runnable) creates them. I don't like the idea of running the whole application in UI thread, but maybe it's just a perfect

I use the following function to create instances of functions in JavaScript from an array of arguments: var instantiate = function (instantiate) { return function (constructor, args, prototype) { "use strict"; if (prototype) { var proto = constructor.prototype; constructor.prototype = prototype; } var instance = instantiate(constructor, args); if (proto) constructor.prototype = proto; return instance; }; }(Function.prototype.apply.bind(function () { var args = Array.prototype.slice.call(arguments); var constructor = Function.prototype.bind.apply(this, [null].concat(args)); return new

I want a way to make functor from function. Now I trying to wrap function call by lambda function and instantiate it later. But compiler says than lambda constructor is deleted. So is there any way to compile this code ? Or maybe another way for that ? #include <iostream> void func() { std::cout << "Hello"; } auto t = []{ func(); }; typedef decltype(t) functor_type; template <class F> void functor_caller() { F f; f(); } int main() { functor_caller<functor_type>(); return 0; } Now I get such compiler error: error: use of deleted function '<lambda()>::<lambda>()' error: a lambda closure type has

I have heard several times that when instantiating objects you should do: "Interface" name = new "Class"(); For example for the class linkedlist that implements List : List<String> name = new LinkedList<String>(); LinkedList implements many interfaces, including queue, deque, etc. What is the difference between the above code and LinkedList<String> name = new LinkedList<String>(); or Queue<String> name = new LinkedList<String>(); Why must the type be specified twice as well; it seems redundant but oracledocs don't seem to mention it. LinkedList<String> name = new LinkedList<String>(); is

Here's a snippet in which I instantiate a new content object in my service: const newContent = new Content( result.obj.name result.obj.user.firstName, result.obj._id, result.obj.user._id, ); The problem is that this way of object instantiation relies on the order of properties in my content model. I was wondering if there's a way to do it by mapping every property to the value I want to set it to, for example: const newContent = new Content( name: result.obj.name, user: result.obj.user. content_id: result.obj._id, user_id: result.obj.user._id, ); const newContent = <Content>({ name: result.obj