title: Check constant is defined but empty?
body: <pre><code>&lt;?php
      define ('foo','');
  if (defined('foo')){
      if (empty(foo)){
          echo "Notice: Foo Is Defined, But Does Not Carry A Value. Please Set It";
      }
  }
  </code></pre>
  
  <p>If have this current script, I am running a set of checks on defined constants which the user needs to define in the configuration page.. The problem is, the config gets shipped out with nothing defined: </p>
  
  <pre><code>define ('foo','');
  </code></pre>
  
  <p>and when running the script, I first check that the necessary constants are correctly defined and do carry a value.</p>
  
  <p>The problem is, that I can get if the value is defined, but I cannot correctly check if it's empty. </p>
  
  <p>I know with empty expects a variable passed, if i pass my defined constants into a variable, doesn't it kinda defeat the point? </p>
  
  <pre><code>&lt;?php
   define ('Foo','');
   $Foo = Foo;
   if (empty($Foo)){
    echo "Foo Is Empty"; 
  }
  ?&gt;
  </code></pre>
  
  <p>Whereas I might aswell setup: </p>
  
  <pre><code>$Foo = 'Value';
  $OtherConstant = 'Another';
  </code></pre>
  
  <p>so how can I check whether my constant is carrying a value when that is defined? </p>