PHP SplObjectStorage::removeAllExcept() Method: Usage and Examples

Retains only objects that also appear in the supplied storage.

The examples focus on the operation itself, including the important distinction: removeAll removes the matching entries instead.

What It Does

Use the examples below to observe the behavior on a small dataset before extending it to application code.

Syntax and Return Value

SplObjectStorage::removeAllExcept(SplObjectStorage $storage)

The displayed signature describes the API or identifies any correction or optional dependency. When a parameter is optional, supply it only when the task requires it.

Parameters

• storage: required.

Example 1: Basic Use

SplObjectStorage retains object identity and can associate independent information with each object; it is not keyed by the label property.

<?php
$one = (object) ["label" => 'alpha'];
$two = (object) ["label" => 'beta'];
$three = (object) ["label" => 'gamma'];
$store = new SplObjectStorage();
$store[$one] = "pending";
$store[$two] = "approved";
$other = new SplObjectStorage();
$other[$two] = "from-other";
$other[$three] = "new";
$store->removeAllExcept($other);
echo json_encode([count($store), $store->contains($two)]);

Output from a successful local PHP 8.4 run:

[1,true]

Example 2: Checking Behavior

SplObjectStorage retains object identity and can associate independent information with each object; it is not keyed by the label property.

<?php
$one = (object) ["label" => 'red'];
$two = (object) ["label" => 'green'];
$three = (object) ["label" => 'blue'];
$store = new SplObjectStorage();
$store[$one] = "pending";
$store[$two] = "approved";
$other = new SplObjectStorage();
$other[$two] = "from-other";
$other[$three] = "new";
$store->removeAllExcept($other);
echo json_encode([count($store), $store->contains($two)]);

Output from a successful local PHP 8.4 run:

[1,true]

Example 3: Practical Example

SplObjectStorage retains object identity and can associate independent information with each object; it is not keyed by the label property.

<?php
$one = (object) ["label" => 'first'];
$two = (object) ["label" => 'second'];
$three = (object) ["label" => 'third'];
$store = new SplObjectStorage();
$store[$one] = "pending";
$store[$two] = "approved";
$other = new SplObjectStorage();
$other[$two] = "from-other";
$other[$three] = "new";
$store->removeAllExcept($other);
echo json_encode([count($store), $store->contains($two)]);

Output from a successful local PHP 8.4 run:

[1,true]

Important Behavior and Edge Cases

This is a filter by object identity, not a filter on attached metadata.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Retains only objects that also appear in the supplied storage.
• This is a filter by object identity, not a filter on attached metadata.
• removeAll removes the matching entries instead.

Use SplObjectStorage::removeAllExcept when its documented behavior matches the problem. Test the relevant edge cases in your own runtime before deploying it.