Calling virtual functions from a constructor or destructor is dangerous and should be avoided whenever possible. All C++ implementations should call the version of the function defined at the level of the hierarchy in the current constructor and no further. The C++ FAQ Lite covers this in section 23.7 in pretty good detail. I suggest … Read more
To use the class, first create an instance, like so: p = Pump() p.getPumps() A full example: >>> class TestClass: … def __init__(self): … print(“init”) … def testFunc(self): … print(“Test Func”) … >>> testInstance = TestClass() init >>> testInstance.testFunc() Test Func
In C++ the only difference between a class and a struct is that members and base classes are private by default in classes, whereas they are public by default in structs. So structs can have constructors, and the syntax is the same as for classes.
You can add a defaulted type argument to the template: template <int otherN, typename = typename std::enable_if<otherN >= N>::type> explicit A(A<otherN> const &);
While the other answers are true, there is a new technique in C++11 for expressing that : deleted default constructor It allows forbidding a function without depending on any other trick. It also clearly express your intention in the code. class X { public: X(int) {} X() = delete; // will never be generated }; … Read more
When you instantiate an object in C++, the code in the constructor is the last thing executed. All other initialization, including superclass initialization, superclass constructor execution, and memory allocation happens beforehand. The code in the constructor is really just to perform additional initialization once the object is constructed. So it is perfectly valid to use … Read more
I think there are multiple aspects that should be taken into consideration: A constructor should initialize an object in a way that it’s in a usable state. A constructor should only initialize an object, not perform heavy work. A constructor should not directly or indirectly call virtual members or external code. So in most cases … Read more
You could do this. There is probably also a jquery way… function Box(obj) { for (var fld in obj) { this[fld] = obj[fld]; } } You can include a test for hasOwnProperty if you’ve (I think foolishly) extended object function Box(obj) { for (var fld in obj) { if (obj.hasOwnProperty(fld)) { this[fld] = obj[fld]; } … Read more
In general, if something is documented as being a constructor, use new with it. But in this case, RegExp has a defined “factory” behavior for the situation where you’ve called it as a function instead. See Section 15.10.3 of the ECMAScript (JavaScript) specification (that links to the outgoing spec; the section number is the same … Read more
Try this: Lazy<myClass> myLazy = new Lazy<myClass>(() => new myClass(InstanceName)); Remember that the expression is evaluated lazily, so if you change the value of the variable InstanceName before the constructor is called it might not do what you expect.