If you do not declare copy-assignment operator in a class, the compiler will declare one for you implicitly. The implicitly declared copy-assignment operator will hide any inherited assignment operators (read about “name hiding” in C++), meaning that any inherited assignment operators will become “invisible” to the unqualified name lookup process (which is what happens when … Read more
Just add the following to the class definition and you should be good to go: __rmul__ = __mul__
and simply returns either the first or the second operand, based on their truth value. If the first operand is considered false, it is returned, otherwise the other operand is returned. Lists are considered true when not empty, so both lists are considered true. Their contents don’t play a role here. Because both lists are … Read more
&& is new in C++11. int&& a means “a” is an r-value reference. && is normally only used to declare a parameter of a function. And it only takes a r-value expression. If you don’t know what an r-value is, the simple explanation is that it doesn’t have a memory address. E.g. the number 6, … Read more
Integers are cached for values between -128 and 127 so Integer i = 127 will always return the same reference. Integer j = 128 will not necessarily do so. You will then need to use equals to test for equality of the underlying int. This is part of the Java Language Specification: If the value … Read more
First, you need to understand the difference between __add__ and __iadd__. An object’s __add__ method is regular addition: it takes two parameters, returns their sum, and doesn’t modify either parameter. An object’s __iadd__ method also takes two parameters, but makes the change in-place, modifying the contents of the first parameter. Because this requires object mutation, … Read more
Python Boolean operators return the last value evaluated, not True/False. The docs have a good explanation of this: The expression x and y first evaluates x; if x is false, its value is returned; otherwise, y is evaluated and the resulting value is returned.
Prior to C++23, you could not overload operator[] to accept multiple arguments. As a workaround, you instead can overload operator(). (See How do I create a subscript operator for a Matrix class? from the C++ FAQ.) From C++23, as mentioned in a (deleted) answer by cigien, multiple subscript arguments can be passed to operator[] directly. … Read more
The key to the answer is called object interning. Java interns small numbers (less than 128), so all instances of Integer(n) with n in the interned range are the same. Numbers greater than or equal to 128 are not interned, hence Integer(1000) objects are not equal to each other.
Not out of the box. However, it’s easy to build by hand in many languages including JS. var operators = { ‘+’: function(a, b) { return a + b }, ‘<‘: function(a, b) { return a < b }, // … }; var op = ‘+’; alert(operators[op](10, 20)); You can use ascii-based names like plus, … Read more