Object State

An object can update its own state across method calls.

object_state.php

<?php
class Counter
{
    public int $value = 0;

    public function add(int $amount): int
    {
        $this->value = $this->value + $amount;
        return $this->value;
    }
}

$step = ;
$counter = new Counter();
$first = $counter->add($step);
$second = $counter->add(3);

echo "first=" . $first . "\n";
echo "second=" . $second . "\n";

<?php
class Counter
{
    public int $value = 0;

    public function add(int $amount): int
    {
        $this->value = $this->value + $amount;
        return $this->value;
    }
}

$step = ;
$counter = new Counter();
$first = $counter->add($step);
$second = $counter->add(3);

echo "first=" . $first . "\n";
echo "second=" . $second . "\n";

<?php
class Counter
{
    public int $value = 0;

    public function add(int $amount): int
    {
        $this->value = $this->value + $amount;
        return $this->value;
    }
}

$step = ;
$counter = new Counter();
$first = $counter->add($step);
$second = $counter->add(3);

echo "first=" . $first . "\n";
echo "second=" . $second . "\n";

state changes Method calls can update stored values, then return a scalar result that the page can display.