First of all, make sure you don't need just a simple built-in bool validation .
Internally behaves same way as (bool)$value, but
- non-scalar values (arrays, resources, objects without __toString etc.) raises exception
- objects with __toString magic method are converted to string by that, then to bool
- null can be rejected by raise of an exception, if desired
<?php
use Granam\Boolean\Boolean;
$booleanFromInteger = new Boolean(12345);
// bool(true)
var_dump($booleanFromInteger->getValue());
$booleanFromString = new Boolean('124578');
// bool(true)
var_dump($booleanFromString->getValue());
$booleanFromFloatString = new Boolean('987.654');
// bool(true)
var_dump($booleanFromFloatString->getValue());
$booleanFromZero = new Boolean(0);
// bool(false)
var_dump($booleanFromZero->getValue());
$booleanFromNull = new Boolean(null, false /* not strict */);
// bool(false)
var_dump($booleanFromNull->getValue());
// ...
// exception is raised (\Granam\Boolean\Tools\Exceptions\WrongParameterType)
new Boolean(null); // implicitly strict - NULL is "unknown" state and therefore forbidden