InvokeableAssurance

Since v1.2016062801

Description

InvokeableAssurance is a trait. It implements the __invoke() and inspect() methods of the Assurance interface for you.

Public Interface

InvokeableAssurance has the following public interface:

// InvokeableAssurance lives in this namespace
namespace GanbaroDigital\Defensive\V1\Assurances;

trait InvokeableAssurance
{
    /**
     * throws exceptions if any of our assurances are not met
     *
     * @param  mixed $data
     *         the data to be examined by each assurance in turn
     * @param  string $fieldOrVarName
     *         what is the name of $data in the calling code?
     * @return void
     */
    public function __invoke($data, $fieldOrVarName = "value");

    /**
     * throws exceptions if any of our assurances are not met
     *
     * this is an alias of to() for readability purposes
     *
     * @param  mixed $data
     *         the data to be examined by each assurance in turn
     * @param  string $fieldOrVarName
     *         what is the name of $data in the calling code?
     * @return void
     */
    public function inspect($data, $fieldOrVarName = "value");
}

How To Use

For Convenience

Use InvokeableAssurance in your own classes to save on typing and code duplication.

use GanbaroDigital\Defensive\V1\Interfaces\Assurances;
use GanbaroDigital\Defensive\V1\Assurances\InvokeableAssurance;

class EnsureInRange implements Assurance
{
    // save us having to declare __invoke() and inspect() ourselves
    use InvokeableAssurance;

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

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

    /**
     * constructor. used to create a customised assurance
     *
     * @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;
    }

    /**
     * generates an Assurance
     *
     * @param  int $min
     *         minimum value for allowed range
     * @param  int $max
     *         maximum value for allowed range
     * @return Assurance
     *         returns a requirement to use
     */
    public static function apply($min, $max)
    {
        return new static($min, $max);
    }

    /**
     * make sure that $data is within the specified range
     * throws an exception if it is not
     *
     * @param  int $data
     *         the value to check
     * @param  string $fieldOrVarName
     *         the name of $data in the caller's code
     * @return void
     */
    public function to($data, $fieldOrVarName = 'value')
    {
        if ($data < $this->min) {
            throw new RuntimeException(
                $fieldOrVarName . ' cannot be less than ' . $this->min
            );
        }
        if ($data > $this->max) {
            throw new RuntimeException(
                $fieldOrVarName . ' cannot be more than ' . $this->max
            );
        }
    }
}

Trait Contract

Here is the contract for this trait:

GanbaroDigital\Defensive\V1\Assurances\InvokeableAssurance
 [x] Can instantiate class that uses trait
 [x] is part of Assurance interface
 [x] calls enclosing classes to method
 [x] passes data to enclosing classes to method
 [x] passes fieldOrVarName to enclosing classes to method
 [x] inspect is an alias for to

Trait contracts are built from this trait's unit tests.

Future releases of this trait will not break this contract.

Future releases of this trait may add to this contract. New additions may include:

  • clarifying existing behaviour (e.g. stricter contract around input or return types)
  • add new behaviours (e.g. extra trait methods)

When you use this trait, you can only rely on the behaviours documented by this contract.

If you:

  • find other ways to use this trait,
  • or depend on behaviours that are not covered by a unit test,
  • or depend on undocumented internal states of this trait,

... your code may not work in the future.

Notes

None at this time.

Changelog

v1.2016081301

See Also