How to use initializer-list loops for modifying elements?

Question

I can easily simulate a for .. in loop using initializer lists for read access

std::list<int> foo, bar, baz;

int main() 
{
  foo.push_back(3);
  foo.push_back(2);
  bar.push_back(1);
  for (auto &x : {foo, bar, baz}) {
    // x.push_back(42);
    std::cout << x.size() << std::endl;
  }
  return 0;
}

This prints:

2
1
0

What should I do so that I can modify the actual objects, just as in the commented line:

// x.push_back(42);

Answer 1

A pointer-based trick that we know from C might be applied as follows

  for (auto x : { &foo, &bar, &baz }) {
    x->push_back(42);
    std::cout << x->size() << std::endl;
  }

However, this assumes that you actually want to work with the original objects, as opposed to their copies. (The code you posted originally actually works with copies.)