#!/usr/bin/perl -l

$a = sub {return @_[0]};
$b = sub {return @_[0]+1};

if (0) {
   $i = $a;
} else {
   $i = $b;
}  

$number = 10;
print &lala ($i);

sub lala{
   my $i = $_[0];
   $res = &{$i}($number) ;
   #have also tried $res = $i->($number) with the same result
}  
__END__
11