Question

I am trying to make a class that can process strings with un defined variables. Is this possible? or is there a better way?

For instance, if I have the following and would like this class Looper to take $str_1 and output it with the variables $fname and $lname filled out … then somewhere else i can reuse Looper class and process $str_2 since they both need $fname and $lname.

class Looper {
    public function processLoop($str){
        $s='';
        $i=0;
        while ($i < 4){
            $fname = 'f' . $i;
            $lname = 'l' . $i;

            $s .= $str . '<br />';
            $i++;
        }
        return $s;
    }
}

$str_1 = "First Name: $fname, Last Name: $lname";
$rl = new Looper;
print $rl->processLoop($str_1);

$str_2 = "Lorem Ipsum $fname $lname is simply dummy text of the printing and typesetting industry";
print $rl->processLoop($str_2);

Answer 1

Why not just use strtr:

$str_1 = "First Name: %fname%, Last Name: %lname%";
echo strtr($str_1, array('%fname%' => $fname, '%lname%' => $lname));

So in the context if your class:

public function processLoop($str){
    $s='';
    $i=0;
    while ($i < 4){
        $tokens = array('%fname%' => 'f' . $i, '%lname%' => 'l' . $i);
        $s .= strtr($str, $tokens) . '<br />';
        $i++;
    }
    return $s;
}

Likewise if you dont want to be dependent on named placeholders you could use positional placeholders via sprintf:

public function processLoop($str){
    $s='';
    $i=0;
    while ($i < 4){
        $s .= sprintf($str, 'f' . $i, l' . $i) . '<br />';
        $i++;
    }
    return $s;
}

In that case your $str argument would look like "First Name: %s, Last Name: %s"

So over all usage:

// with strtr

$str_1 = "First Name: %fname%, Last Name: %lname%";
$rl = new Looper;
print $rl->processLoop($str_1);


// with sprintf

$str_1 = "First Name: %s, Last Name: %s";
$rl = new Looper;
print $rl->processLoop($str_1);