// We say that: // - The name of the input is "Path". // - The input is mandatory. // - The input can not be null. // - The input has a validator. $pathSpecification = new Specification("Path", true, false, $pathValidator); // You can also use mutators to specify an input. // The input named "token" is not mandatory and its value can be null. // It does not have any specific validator. $tokenSpecification = new Specification("Token"); $tokenSpecification->setMandatory(false)->setCanBeNull(); // Create a set of specifications. $set = new SpecificationsSet(); $set->addInputSpecification($pathSpecification)->addInputSpecification($tokenSpecification); // Print a summary. foreach ($set->inputsSummary() as $_name => $_summary) { echo "{$_name} => {$_summary}\n"; } // Note: you may specify a final validator. // If the file exists, and if a token is specified, then make sure that the token is found in the file. // If everything is OK, the validator must return an empty array. // Otherwise, it must return a list of errors' identifiers (you are free to return any kind of values...). // Note: here we return a list of error messages $finalValidator = function ($inInputs) { $data = file_get_contents($inInputs['Path']); if (array_key_exists('Token', $inInputs) && !is_null($inInputs['Token'])) { if (false === strstr($data, $inInputs['Token'])) { return ["The file " . $inInputs['Path'] . " exists, but it does not contain the token <" . $inInputs['Token'] . "> !"]; } else { return []; }