The feature illustrated below operates on PHP values, objects, or language metadata.
What Is method_exists in PHP?
Checks whether a named method is declared on a class or object, including non-public methods; existence does not guarantee accessibility.
method_exists($object_or_class, string $method) : boolParameters:
$object_or_class— Required. The object_or_class argument used to configure this operation; its accepted values follow the declared PHP type.$method— Required. The method name to inspect or invoke.
Return type: bool. A private or protected method can exist even when external code cannot call it.
Example 1: Understanding the Basic Behavior
<?php
class Document { public function save(): void {} }
var_dump(method_exists(Document::class, 'save'));Output:
bool(true)Explanation: Checks whether a named method is declared on a class or object, including non-public methods; existence does not guarantee accessibility.
Example 2: Testing Another Case
<?php
class User { protected function validate(): bool { return true; } }
var_dump(method_exists(new User(), 'validate'));Output:
bool(true)Explanation: A private or protected method can exist even when external code cannot call it.
Practical Example: Applying the Operation
<?php
class Queue { public function process(): void {} }
var_dump(method_exists(Queue::class, 'missing'));Output:
bool(false)Explanation: is_callable() answers a different question about whether a value is callable.
Important Behavior and Edge Cases
- A private or protected method can exist even when external code cannot call it.
- is_callable() answers a different question about whether a value is callable.
Comparison With Related Approaches
| Approach | When to Use It |
|---|---|
method_exists | Checks whether a named method is declared on a class or object, including non-public methods; existence does not guarantee accessibility. |
is_callable() | method_exists() sees methods independent of whether caller can invoke them; is_callable() tests invocability. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Calling a private method from outside the class just because method_exists() returned true. | A private or protected method can exist even when external code cannot call it. |
| Choosing is_callable() without checking whether it provides the same result. | method_exists() sees methods independent of whether caller can invoke them; is_callable() tests invocability. |
Key Takeaways
- Checks whether a named method is declared on a class or object, including non-public methods; existence does not guarantee accessibility.
- A private or protected method can exist even when external code cannot call it.
- is_callable() answers a different question about whether a value is callable.
The examples demonstrate where method_exists fits within php programming. Verify the relevant preconditions whenever you adapt the code to real data.