ListCheck

Description

ListCheck is an interface. It's the interface for true / false inspections of a list of data.

Public Interface

ListCheck has the following public interface:

// ListCheck lives in this namespace
namespace GanbaroDigital\Defensive\V1\Interfaces;

interface ListCheck
{
    /**
     * does a value pass inspection?
     *
     * @param  mixed $fieldOrVar
     *         the data to be examined
     * @return bool
     *         TRUE if the inspection passes
     *         FALSE otherwise
     */
    public function inspect($fieldOrVar);

    /**
     * does a list of values pass inspection?
     *
     * @param  mixed $list
     *         the data to be examined
     * @return bool
     *         TRUE if the inspection passes
     *         FALSE otherwise
     */
    public function inspectList($list);
}

ListCheck also has the following informal interface:

interface ListCheck
{
    /**
     * does a value pass inspection?
     *
     * @param  mixed $fieldOrVar
     *         the data to be examined
     * @return bool
     *         TRUE if the inspection passes
     *         FALSE otherwise
     */
    public static function check($fieldOrVar, <additional params>);

    /**
     * does a list of values pass inspection?
     *
     * @param  mixed $list
     *         the data to be examined
     * @return bool
     *         TRUE if the inspection passes
     *         FALSE otherwise
     */
    public static function checkList($list, <additional params>);
}

Informal interfaces contain methods that you must implement. However, due to PHP limitations, we can't add these methods to the interface at this time.

How To Use

Every ListCheck can be used in two ways:

• a static call to ::checkList() for convenience,
• as an object, calling the ->inspectList() method

Scaffolding

Most ListCheck classes also implement the Check interface too. See the Check interface to get started.

Every ListCheck needs a bit of boilerplate code:

• add use GanbaroDigital\Defensive\V1\Interfaces\ListCheck to your PHP file
• add implements ListCheck to your class

The Check Pattern

Every ListCheck implements the ListCheck::checkList() pattern:

• add a public static function checkList() method to your class. This method inspects each element in $list. If you're happy with $list, return true. If you're not happy with $list, return false.
• if your check needs additional input parameters, pass these in as additional parameters to the checkList() method.

Making It Usable As An Object

Every ListCheck can be used as an object:

• add a public function __construct() if your check needs additional input parameters
• add a public function inspectList() which calls your ::inspect() method

We've provided a ListableCheck trait that will add inspectList() to your class.

Putting It All Together

Here's a simple min / max check. It supports all the different ways that a ListCheck can be used.

use GanbaroDigital\Defensive\V1\Checks\ListableCheck;
use GanbaroDigital\Defensive\V1\Interfaces\Check;
use GanbaroDigital\Defensive\V1\Interfaces\ListCheck;

class IsInRange implements Check, ListCheck
{
    // saves us having to implement inspectList() ourselves
    use ListableCheck;

    /**
     * minimum acceptable value in our range
     */
    private $min;

    /**
     * maximum acceptable value in our range
     */
    private $max;

    /**
     * constructor. used to create a customised check
     *
     * @param  int $min
     *         minimum value for allowed range
     * @param  int $max
     *         maximum value for allowed range
     */
    public function __construct($min, $max)
    {
        $this->min = $min;
        $this->max = $max;
    }

    /**
     * is $data within the require range?
     *
     * @param  int $data
     *         the value to check
     * @return bool
     *         TRUE if the data is in range
     *         FALSE otherwise
     */
    public function inspect($data)
    {
        return static::check($data, $this->min, $this->max);
    }

    /**
     * is $data within the required range?
     *
     * @param  int $data
     *         the value to check
     * @param  int $min
     *         minimum value for allowed range
     * @param  int $max
     *         maximum value for allowed range
     * @return bool
     *         TRUE if the data is in range
     *         FALSE otherwise
     */
    public static function check($data, $min, $max)
    {
        if ($data < $this->min) {
            return false;
        }
        if ($data > $this->max) {
            return false;
        }

        return true;
    }

    /**
     * are the values in $list within the required range?
     *
     * @param  mixed $list
     *         the list of values to check
     * @param  int $min
     *         minimum value for allowed range
     * @param  int $max
     *         maximum value for allowed range
     * @return bool
     *         TRUE if the data is in range
     *         FALSE otherwise
     */
    public static function checkList($list, $min, $max)
    {
        $check = new static($min, $max);
        return $check->inspectList($list);
    }
}

To use this example check, you can do:

// a static call is often the most convenient
var_dump(IsInRange::checkList($list, 10,20));

// as an object
$callable = new IsInRange(10, 20);
var_dump($rangeCheck->inspect($data));
var_dump($rangeCheck->inspectList($list));