This library implements the Specification Pattern for use in any project.
Create composable logic by encapsulating decisions in a class that adheres to the SpecificationInterface.
$ composer require emarref/specGiven the following specifications:
<?php
use Emarref\Spec\SpecificationInterface;
use Emarref\Spec\LogicalSpecificationTrait;
class MorningSpecification implements SpecificationInterface
{
use LogicalSpecificationTrait;
public function isSatisfiedBy($subject): bool
{
if (!$subject instanceof \DateTimeInterface) {
throw new \InvalidArgumentException('Subject must be a date time object.');
}
$hour = (int) $subject->format('G');
return $hour < 12;
}
}
class AfternoonSpecification implements SpecificationInterface
{
use LogicalSpecificationTrait;
public function isSatisfiedBy($subject): bool
{
if (!$subject instanceof \DateTimeInterface) {
throw new \InvalidArgumentException('Subject must be a date time object.');
}
$hour = (int) $subject->format('G');
return $hour > 12 && $hour < 18;
}
}
class NightSpecification implements SpecificationInterface
{
use LogicalSpecificationTrait;
public function isSatisfiedBy($subject): bool
{
if (!$subject instanceof \DateTimeInterface) {
throw new \InvalidArgumentException('Subject must be a date time object.');
}
$hour = (int) $subject->format('G');
return $hour > 17;
}
}We can test if a date is in the morning:
<?php
$morning = new \DateTime('8am');
$isMorning = new MorningSpecification();
$isMorning->isSatisfiedBy($morning); // trueor afternoon:
<?php
$isAfternoon = new AfternoonSpecification();
$isAfternoon->isSatisfiedBy($morning); // falseWe can chain specs together:
<?php
$night = new \DateTime('11pm');
$isMorning->or($isAfternoon)->isSatisfiedBy($morning); // true
$isMorning->or($isAfternoon)->isSatisfiedBy($night); // falseChaining can be deep:
<?php
$isMorning->or($isAfternoon->andNot($isNight))->isSatisfiedBy($morning); // trueBusiness logic can be encapsulated by custom specs. Create a class that
implements the Emarref\Spec\SpecificationInterface. Use the Emarref\Spec\LogicalSpecificationTrait
to implement most of the boilerplate.
<?php
class StoreIsOpen implements SpecificationInterface
{
use LogicalSpecificationTrait;
public function isSatisfiedBy($subject): bool
{
if (!$subject instanceof \DateTimeInterface) {
throw new \InvalidArgumentException('Subject must be a date time object.');
}
$isMorning = new MorningSpec();
$isAfternoon = new AfternoonSpec();
return $isMorning->or($isAfternoon)->isSatisfiedBy($subject);
}
}
$storeIsOpen = new StoreIsOpen();
$storeIsOpen->isSatisfiedBy(new DateTime('10am')); // true
$storeIsOpen->isSatisfiedBy(new DateTime('11pm')); // false
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