Question

How can I make a string act as a code?

For instance, I want this string to be parsed as an array,

$config = '
    "allowable_tags" => "<p>",
    "span_regex" => null, 
    "allow_nbsp" => true, 
    "allow_class" => false
';

so,

function tidy($config = null){

    $default = array(
        "allowable_tags" => null,
        "span_regex" => null, 
        "allow_nbsp" => true, 
        "allow_class" => false
    );

    $config = array($config);

    # Loop the array.
    foreach($default as $key => $value)
    {
        # Set the variable.
        $$key = set_variable($config,$key)? set_variable($config,$key):$value;
    }

    return $allowable_tags;
}


var_dump(tidy($config));

Then I will get this as the result,

<p>

Is it feasible?

the dependant function,

function set_variable($array = array(),$key,$params = array())
{
    # If $params is not an array, let's make it array with one value of former $params.
    if(!is_array($params)) $params = array($params);
    if(!is_array($array)) parse_str($array, $array);

    # When you want a variable to return a boolean, this will return true or false.
    if(in_array('boolean', $params)) return isset($array[$key]) && $array[$key] === true ? true : false;

    # This will regard '0' as a string.
    # Return value or 0 as a string.
    elseif(in_array('zero_to_string', $params)) return isset($array[$key]) && ($array[$key] == '0') ? trim($array[$key]) : null;

    # Return null as string if 'null_to_string' is set.
    elseif(in_array('null_to_string', $params)) return isset($array[$key]) && !empty($array[$key]) ? trim($array[$key]) : 'null';

    # Check if the key is an array.
    elseif(isset($array[$key]) && !empty($array[$key]) && is_array($array[$key])) return isset($array[$key]) && !empty($array[$key]) ? $array[$key] : null;

    # This will regard '0', empty space as falsey.
    # Return value or null.
    else return isset($array[$key]) && !empty($array[$key]) ? trim($array[$key]) : null;
}

Answer 1

instead of making a custom function to parse the string representation of config vars to an array, why not just use an existing format such as JSON? then you can simply call json_decode() and get an array back. Also if this is for user submitted/entered config values, JSON is widely known, easy to learn and somewhat safe because no code is executed.