An interface for objects that expose type-safe getter methods.

Throughout PHP.GT repositories, wherever an object represents enclosed data, a consistent interface is used to expose the data in a type-safe manner.

---

This package defines:

• GT\TypeSafeGetter\TypeSafeGetter
• GT\TypeSafeGetter\NullableTypeSafeGetter
• GT\TypeSafeGetter\CallbackTypeSafeGetter

The usual pattern is to implement get() yourself and use the NullableTypeSafeGetter trait for the common typed methods.

use DateTimeImmutable;
use DateTimeInterface;
use GT\TypeSafeGetter\NullableTypeSafeGetter;
use GT\TypeSafeGetter\TypeSafeGetter;

class DataStore implements TypeSafeGetter {
	use NullableTypeSafeGetter;

	public function __construct(
		private readonly array $data = [],
	) {}

	public function get(string $name):mixed {
		return $this->data[$name] ?? null;
	}
}

$store = new DataStore([
	"id" => "42",
	"active" => 1,
	"created" => "2024-05-01 09:15:00",
]);

echo $store->getInt("id");
var_dump($store->getBool("active"));
echo $store->getDateTime("created")?->format("Y-m-d");

getInstance() returns an existing object after checking its type:

$store = new DataStore([
	"date" => new DateTimeImmutable("2024-05-01"),
]);

$date = $store->getInstance("date", DateTimeInterface::class);

getDateTime() accepts:

• DateTimeInterface instances
• Unix timestamps
• date/time strings supported by DateTimeImmutable

The following methods are defined by this interface:

• get(string $name):mixed - A non-type-safe getter, used for getting keys that are not of an inbuilt type
• getString(string $name):?string
• getInt(string $name):?int
• getFloat(string $name):?float
• getBool(string $name):?bool
• getDateTime(string $name):?DateTimeInterface
• getInstance(string $name, class-string<T> $className):?T

Common areas you will see this interface used:

• Database rows
• User input (from the query string or posted form data)
• Session and cookie storage
• HTTP header collections
• Configuration objects
• PHP.GT's DataObject repository.

NullableTypeSafeGetter trait

A lot of repositories within PHP.GT that utilise this class were repeating the same getter code, so this trait was introduced to remove the repetition. All getter functions of the interface are implemented, introducing a protected helper function getNullableType which removes the repetition of checking null values before casting them. The getNullableType function also allows a callback to be passed as the type parameter, allowing more complex nullable types to be constructed.

CallbackTypeSafeGetter interface

This interface is for callback-driven lookups where a value may need to be fetched or computed as part of the read operation, such as cache APIs.

Unlike NullableTypeSafeGetter, there is no trait implementation in this package for the callback interface. Implementing classes define their own callback behaviour.

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