Function return as lvalue in C++

assign_to_return.cpp

#include <iostream>

int& foo() {
  static int pointless_static_var = 23;
  return pointless_static_var;
}

int main(int argc, char** argv) {
  std::cout << "foo() = 42: " << (foo() = 42) << std::endl;
}

// Outputs:
//   foo() = 42: 42

A similar argument is applicable in JavaScript-land, where I see many (particularly nodejs) programmers use comma-first variable declaration.

var ruby = "is pretty cool"
  , yoda = "not so pretty think yoda does"

This type of notation will trigger syntax errors when you make a mistake, which is preferable to creating globals accidentally.