overloading

In Python 2.6 (and earlier) the hex() and oct() built-in functions can be overloaded in a class by defining __hex__ and __oct__ special functions. However there is not a __bin__ special function for overloading the behaviour of Python 2.6's new bin() built-in function. I want to know if there is any way of flexibly overloading bin() , and if not I was wondering why the inconsistent interface? I do know that the __index__ special function can be used, but this isn't flexible as it can only return an integer. My particular use case is from the bitstring module, where leading zero bits are

I'm having some trouble using multiple constructors in java. what I want to do is something like this: public class MyClass { // first constructor public MyClass(arg1, arg2, arg3) { // do some construction } // second constructor public MyClass(arg1) { // do some stuff to calculate arg2 and arg3 this(arg1, arg2, arg3); } } but I can't, since the second constructor cannot call another constructor, unless it is the first line. What is the common solution for such situation? I can't calculate arg2 and arg3 "in line". I thought maybe creating a construction helper method, that will do the actual

I have a C background. I was just wondering why was function overloading added to C++? C doesn't have function overloading but C++ does, what was the need for it? What went across the mind of the language designer at that time? It increases maintainability. If you have a type T and you call a function with it, then you need to change T, if the function has been overloaded for the new T then you can recompile instantly. In C you would have to go back and dig through all the call sites and change the function called. Take sqrt(). If you want to sqrt() a float, then you have to change to sqrtf().

Just by experiment I discovered that Java non static methods overrides all same named methods in scope even at static context. Even without allowing parameter overloading. Like import java.util.Arrays; import static java.util.Arrays.toString; public class A { public static void bar(Object... args) { Arrays.toString(args); toString(args); //toString() in java.lang.Object cannot be applied to (java.lang.Object[]) } } I can't find anything about this in spec. Is this a bug? If it isn't, are there any reasons to implement language like that? UPD: Java 6 do not compile this example. The question is

#include <iostream> using namespace std; template<typename T> void f(T&&) { cout << "f(T&&)" << endl; } template<typename T> void f(const T&&) { cout << "f(const T&&)" << endl; } struct A {}; const A g1() { return {}; } const int g2() { return {}; } int main() { f(g1()); // outputs "f(const T&&)" as expected. f(g2()); // outputs "f(T&&)" not as expected. } The issue description is embedded in the code. My compiler is clang 5.0 . I just wonder: Why does C++ treat built-in types and custom types differently in such a case? I don't have a quote from the standard, but cppreference confirms my

Possible Duplicate: defining “boolness” of a class in python I thought this should print "False", why is it printing "True"? >>> class Foo(object): ... def __bool__(self): ... return False ... >>> f = Foo() >>> if f: ... print "True" ... else: ... print "False" ... True >>> You should define __nonzero__() in Python 2.x. It was only renamed to __bool__() in Python 3.x. (The name __nonzero__() actually predates the introduction of the bool type by many years.) 来源： https://stackoverflow.com/questions/8909932/how-to-overload-pythons-bool-method