title: Expression in backticks with Perl `'cmd'.join ...`
body: <p>I would like to send the remaining <code>@ARGV</code> to <code>foo</code>. I currently do this: </p>
  
  <pre><code>my $cmd = 'foo '.join ' ', @ARGV;
  my $out = `$cmd`;
  </code></pre>
  
  <p>Is there possible to do it in one line? For instance with a non-existent <code>e</code> option:</p>
  
  <pre><code>my $out = qx/'foo'.join ' ', @ARGV/e;
  </code></pre>
  
  <p>In a more general case I might want to do this:</p>
  
  <pre><code>my $out = qx/'foo?.join(' ', keys %hash)/e;
  </code></pre>