ReflectionClass inspects the definition of a class, rather than running its constructor or calling its methods.
What Is ReflectionClass::isInternal in PHP?
Reports whether the class is supplied by PHP or an installed extension rather than user source code.
ReflectionClass::isInternal()This operation does not accept method arguments.
Example 1: Understanding the Basic Behavior
<?php
$reflectionClass = new ReflectionClass(DateTimeImmutable::class);
var_dump($reflectionClass->isInternal());Output:
bool(true)Explanation: Reports whether the class is supplied by PHP or an installed extension rather than user source code.
Example 2: Testing Another Case
<?php
interface Exportable { public function export(): string; }
trait HasId { public function getId(): int { return 12; } }
class Invoice implements Exportable { use HasId; public string $name = 'Invoice'; public const STATE = 'open'; public function export(): string { return 'invoice'; } }
$reflectionClass = new ReflectionClass(Invoice::class);
$result = $reflectionClass->isInternal();
var_dump($result);Output:
bool(false)Explanation: PHP or extension-provided types report true; ordinary application-defined classes report false.
Practical Example: Applying the Operation
<?php
abstract class BaseJob { protected string $name = 'job'; abstract public function run(): void; }
class CompletedJob extends BaseJob { public function run(): void {} }
$reflectionClass = new ReflectionClass(CompletedJob::class);
$result = $reflectionClass->isInternal();
var_dump($result);Output:
bool(false)Explanation: The returned metadata may be false, null, an array, or a Reflection object depending on the requested property.
Important Behavior and Edge Cases
- PHP or extension-provided types report true; ordinary application-defined classes report false.
- The returned metadata may be false, null, an array, or a Reflection object depending on the requested property.
Comparison With Related Approaches
| Approach | When to Use It |
|---|---|
ReflectionClass::isInternal | Reports whether the class is supplied by PHP or an installed extension rather than user source code. |
ReflectionClass::getExtensionName() | isInternal() reports whether PHP or an extension supplies the class; getExtensionName() identifies the extension if present. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Confusing a class-declaration check by ReflectionClass::isInternal() with an invocation of the class itself. | PHP or extension-provided types report true; ordinary application-defined classes report false. |
| Choosing ReflectionClass::getExtensionName() without checking whether it provides the same result. | isInternal() reports whether PHP or an extension supplies the class; getExtensionName() identifies the extension if present. |
Key Takeaways
- Reports whether the class is supplied by PHP or an installed extension rather than user source code.
- PHP or extension-provided types report true; ordinary application-defined classes report false.
- The returned metadata may be false, null, an array, or a Reflection object depending on the requested property.
The examples demonstrate where ReflectionClass::isInternal fits within reflection and metadata. Verify the relevant preconditions whenever you adapt the code to real data.