PHP CallbackFilterIterator::accept() Method: Usage and Examples

The PHP CallbackFilterIterator::accept API performs a focused operation on an object or value. The examples below show its effect on actual data.

Decides whether the current entry passes a filter and should be exposed during iteration.

What Is CallbackFilterIterator::accept in PHP?

Decides whether the current entry passes a filter and should be exposed during iteration.

Syntax:

CallbackFilterIterator::accept()

This operation has no parameters.

Return type declared by PHP: mixed / not explicitly declared. The value or side effect is demonstrated in the examples below.

Example 1: Basic Usage

This example uses a small input to make the main behavior visible.

<?php

$filterIterator = new CallbackFilterIterator(new ArrayIterator([3, 10, 12, 15]), fn(int $number): bool => $number > 9);
foreach ($filterIterator as $number) { echo $number . "\n"; }

Output:

10
12
15

Decides whether the current entry passes a filter and should be exposed during iteration.

Example 2: A Different Input

A different set of values shows the same operation in another situation.

<?php

$filterIterator = new CallbackFilterIterator(new ArrayIterator([1, 5, 11, 18]), fn(int $number): bool => $number > 4);
foreach ($filterIterator as $number) { echo $number . "\n"; }

Output:

5
11
18

Only items for which the callback returns true are exposed by iteration.

Practical Example: Applying the Feature

This example shows an application-style use of the feature, with its surrounding setup visible.

<?php

$filterIterator = new CallbackFilterIterator(new ArrayIterator([0, 20, 30, 40]), fn(int $number): bool => $number > 25);
foreach ($filterIterator as $number) { echo $number . "\n"; }

Output:

30
40

The code is shown for learning. Adjust the class names, inputs and error handling to suit your application.

Important Behavior and Edge Cases

• Only items for which the callback returns true are exposed by iteration.
• Decides whether the current entry passes a filter and should be exposed during iteration.
• Observe differences in empty inputs, invalid states and optional extension availability where relevant.

Comparison With Related Approaches

Common Beginner Mistakes

Key Takeaways

• Decides whether the current entry passes a filter and should be exposed during iteration.
• Only items for which the callback returns true are exposed by iteration.
• Use the example that matches the values, runtime version and dependencies in your application.

CallbackFilterIterator::accept 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.