php - How to use an object method as a callback function

Question

I have the below method in a singleton class

private function encode($inp)
{
    if (is_array($inp) {
        return array_map('$this->encode', $inp);
    } else if is_scalar($inp) {
        return str_replace('%7E', rawurlencode($inp));
    } else {
        return '';
    }
}

this works fine as an ordinary function

function encode($inp)
{
    if (is_array($inp) {
        return array_map('encode', $inp);
    } else if is_scalar($inp) {
        return str_replace('%7E', rawurlencode($inp));
    } else {
        return '';
    }
}

when using inside a class i'm getting the below error:

PHP Warning: array_map(): The first argument, '$this->rfc_encode', should be either NULL or a valid callback

Please could anybody help me to fix this.

Answer 1

From PHP Manual on Callbacks:

A method of an instantiated object is passed as an array containing an object at index 0 and the method name at index 1.

So try

return array_map(array($this, 'encode'), $inp);