Binding closures to objects in PHP - Time & Space Complexity

Time Complexity: Binding closures to objects

O(n)

Understanding Time Complexity

We want to understand how the time it takes to run code changes when we bind closures to objects in PHP.

Specifically, how does the number of operations grow as the number of bindings increases?

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

class MyClass {
    public $value;
}

$closure = function() {
    return $this->value;
};

$objects = [];
for ($i = 0; $i < $n; $i++) {
    $obj = new MyClass();
    $obj->value = $i;
    $boundClosure = $closure->bindTo($obj, MyClass::class);
    $objects[] = $boundClosure();
}
    

This code creates $n objects, binds the same closure to each object, and calls it to get a value.

Identify Repeating Operations

Identify the loops, recursion, array traversals that repeat.

• Primary operation: The for-loop that creates objects, binds the closure, and calls it.
• How many times: Exactly n times, once for each object.

How Execution Grows With Input

Each iteration does a fixed amount of work: creating an object, binding the closure, and calling it.

Input Size (n)	Approx. Operations
10	About 10 times the fixed work
100	About 100 times the fixed work
1000	About 1000 times the fixed work

Pattern observation: The total work grows directly in proportion to n.

Final Time Complexity

Time Complexity: O(n)

This means the time to run the code grows linearly as the number of objects increases.

Common Mistake

[X] Wrong: "Binding a closure to an object is instant and does not add to the time cost."

[OK] Correct: Binding actually creates a new closure context each time, so doing it repeatedly adds time proportional to how many times you do it.

Interview Connect

Understanding how binding closures affects performance helps you write efficient PHP code and shows you can think about how code scales with input size.

Self-Check

"What if we bind the closure once outside the loop and reuse it for all objects? How would the time complexity change?"