Programmer - What's the best way to conditionally include an element in a list?

Programmer Question

Possible ways:

1. Using push:

   
   
   

   my @list;  
   push @list, 'foo' if $foo;  
   push @list, 'bar' if $bar;  
   




2. Using the conditional operator:

   
   
   

   my @list = (  
       $foo ? 'foo' : (),    
       $bar ? 'bar' : (),              
   );
   




3. Using the x!! Boolean list squash operator:

   
   
   

   my @list = (  
       ('foo') x!! $foo,  
       ('bar') x!! $bar,  
   );  
   

Which one is better and why?