A function for converting callables to values, or allowing values to simply pass through.

maybeConvertCallable.php

<?php

/**
 * Check if value is a callable, if so, covert the callable to a value.
 * Accepts any number of additional arguments, all of which will be passed to the callable.
 *
 * @param callable|mixed $value
 *
 * @return mixed
 */
protected function maybe_convert_callable( $value ) {

  if ( is_callable( $value ) ) {
    $args = func_get_args();
    array_shift( $args );
    $value = call_user_func_array( $value, $args );
  }

  return $value;
}