delete $log_count{$a--} if it=0;

##</code><code>##

delete $hash{some_destructive_function()} if it==0

##</code><code>##

$code = c{ $a = 1; $b=2; print $a + $b}

##</code><code>##

sub printer {
  my $expr = shift;
  return c{
    sub {
      my $x = shift;
      my $y = shift;
      print $$expr;
    }
  }
}

##</code><code>##

$adder_code = printer( c{ $x + $y } }
$adder_sub = compile($adder_code)
&{$adder_sub}(1, 2)
# prints 3
$pythago_code = printer( c{ sqrt($x**2 + $y**2) } }
$pythago_sub = compile($pythago_code)
&{$pythago_sub}(3, 4)
# prints 5

##</code><code>##

macro printer {
  my $expr = shift;
  return c{
    sub {
      my $x = shift;
      my $y = shift;
      print $$expr;
    }
  }
}

##</code><code>##

# printer is a macro, so $x + $y is not evaluated
$adder_sub = printer( $x + $y }
&{$adder_sub}(1, 2)
# prints 3

##</code><code>##

macro aif {
  my $condition = shift;
  my $body = shift;
  return c{
    {
      my $it = $$condition;
      if ($it) {
        $$body;
      }
    }
  }
}

##</code><code>##

aif(number_of_widgets(),
    {
      print "there are $it widgets\n";
    }
)