str_replace() function and multiple variables?

This is going to be pretty hard to explain, so I'll try to make it as much of a chronological story as possible and end with the question, so that anyone who needs a relatively in-depth idea of what I'm talking about has one :).

I have a theme template with four text containers named primary_headline, primary_subline, secondary_headline and secondary_subtext. The content for each container comes from echo($container_name).

Each container has it's own variable, $container_name, which posts user created content to from a form, contents which sometimes contains the variables $city_name and $ref_name as raw data (i.e. "Hello, I'm from $city_name"), as $city_name and开发者_开发技巧 $ref_name has assigned values, for arguments sake let's just say $city_name= Dallas and $ref_name = Facebook.

Originally, I believed that I only wanted the user to be able to use $city_name and $ref_name within the secondary_subtext container, and I was also going to make the option to use $city_name OR $ref_name the choice of the user in the first place (they'd have to select one, or the other, or none - but couldn't select both.

However, I now want to allow $city_name AND $ref_name across all four container variables ($secondary_subtext for example).

So, my question is, how do I go about doing that in the easiest possible fashion?

Here's my old code for good measure:

if($geo_text == "enable") {
    $geo_init = include("inc/geo_text.php");
    $secondary_headline = str_replace('$city_name', $city_name, $_POST['secondary_headline']); // $_POST data from user
} else($ref_text == "enable") {
    $ref_init = include("inc/ref_text.php");
    $secondary_headline = str_replace('$ref_name', $ref_name, $_POST['secondary_headline']); // $_POST data from user
} else { $secondary_headline = $_POST['secondary_headline']; }

Any comments/answers etc will be very greatly appreciated :)!!

$placeholders = array('city_name','ref_name');
$include_mapper('geo_text' => 'inc/geo_text.php','ref_text'=>'inc/ref_text.php');
$containers = array('first_headline','scondary_headline');

$found = 0;
foreach ($include_mapper as $map => $include){
    if ($$map == "enable"){
        include ($include_mapper[$map]);
        foreach ($container as $container){
            foreach ($placeholders as $placeholder){
                $$container = str_replace('$'.$placeholder, $$placeholder, $_POST[$container];
            }
        }
      $found = 1;
      break;
    }
}
if (!$found){
    foreach ($container as $container){
        $$container = $_POST[$container];
    }
}