Strictly speaking, the result of a copy assignment operator doesn’t need to return a reference, though to mimic the default behavior the C++ compiler uses, it should return a non-const reference to the object that is assigned to (an implicitly generated copy assignment operator will return a non-const reference – C++03: 12.8/10). I’ve seen a … Read more
Yes, but you don’t provide it with a parameter: class Vector { … Vector operator-() { // your code here } }; Note that you should not return *this. The unary – operator needs to create a brand new Vector value, not change the thing it is applied to, so your code may want to … Read more
I have used the comma operator in order to index maps with multiple indices. enum Place {new_york, washington, …}; pair<Place, Place> operator , (Place p1, Place p2) { return make_pair(p1, p2); } map< pair<Place, Place>, double> distance; distance[new_york, washington] = 100;
First of all I’d like to note that you cannot even rely on the fact that (-1) % 8 == -1. the only thing you can rely on is that (x / y) * y + ( x % y) == x. However whether or not the remainder is negative is implementation-defined. Reference: C++03 paragraph … Read more
The problem here is that the + operator has (at least) two different meanings in Python: for numeric types, it means “add the numbers together”: >>> 1 + 2 3 >>> 3.4 + 5.6 9.0 … and for sequence types, it means “concatenate the sequences”: >>> [1, 2, 3] + [4, 5, 6] [1, 2, … Read more
As Selman22 said, you are overriding the default object.Equals method, which accepts an object obj and not a safe compile time type. In order for that to happen, make your type implement IEquatable<Box>: public class Box : IEquatable<Box> { double height, length, breadth; public static bool operator ==(Box obj1, Box obj2) { if (ReferenceEquals(obj1, obj2)) … Read more
You can overload operator[] to return an object on which you can use operator[] again to get a result. class ArrayOfArrays { public: ArrayOfArrays() { _arrayofarrays = new int*[10]; for(int i = 0; i < 10; ++i) _arrayofarrays[i] = new int[10]; } class Proxy { public: Proxy(int* _array) : _array(_array) { } int operator[](int index) … Read more
The problem is that you define it inside the class, which a) means the second argument is implicit (this) and b) it will not do what you want it do, namely extend std::ostream. You have to define it as a free function: class A { /* … */ }; std::ostream& operator<<(std::ostream&, const A& a);
You can do this with ES6 Proxy (available in all modern browsers) var handler = { get: function(target, name) { return “Hello, ” + name; } }; var proxy = new Proxy({}, handler); console.log(proxy.world); // output: Hello, world console.log(proxy[123]); // output: Hello, 123 Check details on MDN.
Yep, it’s easy to implement everything in terms of e.g. __lt__ with a mixin class (or a metaclass, or a class decorator if your taste runs that way). For example: class ComparableMixin: def __eq__(self, other): return not self<other and not other<self def __ne__(self, other): return self<other or other<self def __gt__(self, other): return other<self def __ge__(self, … Read more