README

PHP provide scalar type hinting since PHP 7.0, but no native function is able to protect us against value lost on cast.

For that reason, if we want to be sure about scalar type, a scalar converter and optionally a type-checking class are the only chance.

Warning: The converter and so the wrapper class does not cast null - it remains null.

<?php
namespace Granam\Scalar;

$scalar = new Scalar('foo');

// foo
echo $scalar;

$nullScalar = new Scalar(null);
// false
echo is_scalar($nullScalar->getValue());
// true
echo is_null($nullScalar->getValue());

// NULL
var_dump(ToScalar::toScalar(null);

try {
  Tools\ToScalar(null, true /* explicitly strict */);
} catch (Tools\Exceptions\WrongParameterType $scalarException) {
  // Something get wrong: Expected scalar or object with __toString method on strict mode, got NULL.
  die('Something get wrong: ' . $scalarException->getMessage());
}

Why the NULL remains NULL by default? Because it is the lesser evil, to do not force a type to an unknown value (which NULL is - the "unknown"). If you want to be sure about scalar type, use StrictScalar instead. But still, the NULL to scalar cast have to be done by you.