That’s because b += 1.0; is equivalent to b = (int) ((b) + (1.0));. The narrowing primitive conversion (JLS 5.1.3) is hidden in the compound assignment operation. JLS 15.26.2 Compound Assignment Operators (JLS Third Edition): A compound assignment expression of the form E1 op= E2 is equivalent to E1 = (T)((E1) op (E2)), where T … Read more
This is just guesswork on my part, but: 1. It’s hard to implement this in a single-pass compiler Lua’s bytecode compiler is implemented as a single-pass recursive descent parser that immediately generates code. It does not parse to a separate AST structure and then in a second pass convert that to bytecode. This forces some … Read more
Remember that a += x really means a = a + x. The key point to understand is that addition is evaluated from left to right — that is, the a in a + x is evaluated before x. So let’s figure out what b = (a += (a += a)) does. First we use … Read more
From C++11 5.17 Assignment and compound assignment operators: The behavior of an expression of the form E1 op = E2 is equivalent to E1 = E1 op E2 except that E1 is evaluated only once. However, you’re mixing up logical AND which does short-circuit, and the bitwise AND which never does. The text snippet &&=, … Read more
Why did the logical operators get left out? Is there a good technical reason why it is hard? They didn’t. You can do &= or |= or ^= if you want. bool b1 = false; bool b2 = true; b1 |= b2; // means b1 = b1 | b2 The || and && operators do … Read more
An operation like a op= b; is equivalent to a = a op b;. An assignment can be used as statement or as expression, while as expression it yields the assigned value. Your statement … k += c += k += c; … can, since the assignment operator is right-associative, also be written as k … Read more
Reason The operators &&= and ||= are not available on Java because for most of the developers these operators are: error-prone useless Example for &&= If Java allowed &&= operator, then that code: bool isOk = true; //becomes false when at least a function returns false isOK &&= f1(); isOK &&= f2(); //we may expect … Read more
The |= is a compound assignment operator (JLS 15.26.2) for the boolean logical operator | (JLS 15.22.2); not to be confused with the conditional-or || (JLS 15.24). There are also &= and ^= corresponding to the compound assignment version of the boolean logical & and ^ respectively. In other words, for boolean b1, b2, these … Read more
Use: h.className = h.className + (h.className ? ‘ error’ : ‘error’) You want the operator to work for h.className. Better be specific about it. Of course, no harm should come from h.className += ‘ error’, but that’s another matter. Also, note that + has precedence over the ternary operator: JavaScript Operator Precedence
In Python, += is sugar coating for the __iadd__ special method, or __add__ or __radd__ if __iadd__ isn’t present. The __iadd__ method of a class can do anything it wants. The list object implements it and uses it to iterate over an iterable object appending each element to itself in the same way that the … Read more