Description:
------------
Many languages such as Perl, Java, C++ support lexically scoped variables. Lexical scope allows a variable to exist only within its containing closure. Using lexically scoped (and therefore also declared) variables prevents a whole lot of accidental bugs, memory waste, and poor code design.

Perl has the "my" declaration to achieve this:
http://www.developer.com/lang/perl/article.phpr/3323421

There will have to be some kind of pragma to turn on this feature only in functions or files where it's wanted.

Reproduce code:
---------------
my $person = new Person("Joe");

if ($person->isHomeless()) {
  my $house = new House();
  while (!$house->isComplete()) {
    $house->addBricks();
  }
  $person->assignHome($house);
}

// $house no longer exists here.

if ($person->isHungry()) {
  my $food = array('bannanas', 'chocolate');
  $person->eat($food);
}

// $food no longer exists here.