There's a point where I have problems, thought

sub foo
{ ## start of visible scope

  ## $x a lexical var only accessable in the *visible* scope
     my $x = "a lexical var";

  ## $y changed for the *length* of the scope
  local $y = "a dynamic var";

  print "foo(\$x):  $x\n";
  print "foo(\$y):  $y\n";

  bar($y);

} ## end of visible scope

sub bar {
  ## $x is undefined as it is being referenced outside the
  ## *visible* scope of foo()

  ## $y is still changed as the scope of foo() has not
  ## *exitted* yet

  print "bar(\$x):  $x\n";
  print "bar(\$y):  $y\n";
}

$y = "a global var";

foo();

## now foo() has exitted $y reverts to it's original value
print "main(\$y): $y\n";

__output__

foo($x):  a lexical var
foo($y):  a dynamic var
bar($x):  
bar($y):  a dynamic var
main($y): a global var
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_________
broquaint