The NoDiscard attribute in PHP 8.5 warns when a function or method return value is silently ignored.
The examples below begin with the core behavior, then move to an application-oriented use.
How PHP 8.5 NoDiscard Attribute: Preventing Ignored Return Values Works
The NoDiscard attribute in PHP 8.5 warns when a function or method return value is silently ignored.
Compatibility note: Requires PHP 8.5 or later.
Example 1: Basic Usage
This example uses a small input to make the main behavior visible.
<?php
#[NoDiscard]
function saveDraft(string $text): bool { return $text !== ""; }
$wasSaved = saveDraft("Hello");
var_dump($wasSaved);The NoDiscard attribute in PHP 8.5 warns when a function or method return value is silently ignored.
Example 2: A Different Input
A different set of values shows the same operation in another situation.
<?php
#[NoDiscard]
function parseTicket(string $ticket): ?int { return ctype_digit($ticket) ? (int) $ticket : null; }
$ticketId = parseTicket("42");
var_dump($ticketId);It raises a warning, not a runtime exception; use the returned result or explicitly discard it when intentional.
Practical Example: Applying the Feature
This example shows an application-style use of the feature, with its surrounding setup visible.
<?php
#[NoDiscard]
function updateInventory(int $available): int { return max(0, $available - 1); }
$remaining = updateInventory(10);
echo "Remaining: $remaining";The code is shown for learning. Adjust the class names, inputs and error handling to suit your application.
Important Behavior and Edge Cases
- It raises a warning, not a runtime exception; use the returned result or explicitly discard it when intentional.
- The NoDiscard attribute in PHP 8.5 warns when a function or method return value is silently ignored.
- Observe differences in empty inputs, invalid states and optional extension availability where relevant.
Comparison With Related Approaches
| Approach | Important Difference |
|---|---|
PHP 8.5 NoDiscard Attribute: Preventing Ignored Return Values | The NoDiscard attribute in PHP 8.5 warns when a function or method return value is silently ignored. |
| Alternative approach | Documentation alone cannot enforce the same return-value acknowledgment. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
Ignoring the documented state or precondition of PHP 8.5 NoDiscard Attribute: Preventing Ignored Return Values | It raises a warning, not a runtime exception; use the returned result or explicitly discard it when intentional. |
| Expecting a different type of result | Read the declared return type and distinguish returned values from changes to the source object. |
| Assuming a related API works identically | Documentation alone cannot enforce the same return-value acknowledgment. |
Key Takeaways
- The NoDiscard attribute in PHP 8.5 warns when a function or method return value is silently ignored.
- It raises a warning, not a runtime exception; use the returned result or explicitly discard it when intentional.
- Use the example that matches the values, runtime version and dependencies in your application.
PHP 8.5 NoDiscard Attribute: Preventing Ignored Return Values is useful when its behavior matches the data structure and lifecycle of your PHP application. Choose it with a clear understanding of its preconditions and returned values.