title: push in array with auto-create in ruby
body: <p>i want to know if it's possible to push in array with auto-creation of array if doesn't exist already, like in PHP:</p>
  
  <pre><code>$toto[] = 'titi';
  </code></pre>
  
  <p>if $toto is not already defined, it will create array and push 'titi' into. If already exist, it will just push.</p>
  
  <p>in Ruby i have to do:</p>
  
  <pre><code>toto ||= []
  toto.push('titi')
  </code></pre>
  
  <p>It's possible to do this in one line?</p>
  
  <p>Because if i have an loop, it will test "||=" for nothing except the first time:</p>
  
  <pre><code>Person.all.each do |person|    
     toto ||= [] #with 1 billion of person, this line is useless 999 999 999 times...
     toto.push(person.name)
  </code></pre>
  
  <p>have you a better solution?</p>
  
  <p>thx.</p>