One of the primary goal when overloading operator() is to create a functor. A functor acts just like a function, but it has the advantages that it is stateful, meaning it can keep data reflecting its state between calls. Here is a simple functor example : struct Accumulator { int counter = 0; int operator()(int … Read more
You need to use the __getitem__ method. class MyClass: def __getitem__(self, key): return key * 2 myobj = MyClass() myobj[3] #Output: 6 And if you’re going to be setting values you’ll need to implement the __setitem__ method too, otherwise this will happen: >>> myobj[5] = 1 Traceback (most recent call last): File “<stdin>”, line 1, … Read more
The assignment operator is not required to be made virtual. The discussion below is about operator=, but it also applies to any operator overloading that takes in the type in question, and any function that takes in the type in question. The below discussion shows that the virtual keyword does not know about a parameter’s … Read more
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.
According to the specification, TypeScript does support method overloading, but it’s quite awkward and includes a lot of manual work checking types of parameters. I think it’s mostly because the closest you can get to method overloading in plain JavaScript includes that checking too and TypeScript tries to not modify actual method bodies to avoid … Read more
A much neater way to get ‘alternate constructors’ is to use classmethods. For instance: >>> class MyData: … def __init__(self, data): … “Initialize MyData from a sequence” … self.data = data … … @classmethod … def fromfilename(cls, filename): … “Initialize MyData from a file” … data = open(filename).readlines() … return cls(data) … … @classmethod … … Read more
-> This is the only really tricky one. It must be a nonstatic member function, and it takes no arguments. The return value is used to perform the member lookup. If the return value is another object of class type, not a pointer, then the subsequent member lookup is also handled by an operator-> function. … Read more
Use ReferenceEquals: Foo foo1 = null; Foo foo2 = new Foo(); Assert.IsFalse(foo1 == foo2); public static bool operator ==(Foo foo1, Foo foo2) { if (object.ReferenceEquals(null, foo1)) return object.ReferenceEquals(null, foo2); return foo1.Equals(foo2); }
There is no immediate answer; operators are static, and cannot be expressed in constraints – and the existing primatives don’t implement any specific interface (contrast to IComparable[<T>] which can be used to emulate greater-than / less-than). However; if you just want it to work, then in .NET 3.5 there are some options… I have put … Read more
you can find how to do it here. In short it is: public object this[int i] { get { return InnerList[i]; } set { InnerList[i] = value; } } If you only need a getter the syntax in answer below can be used as well (starting from C# 6).