Static Properties and Methods

Static members belong to a class rather than a particular object instance.

The examples focus on the operation itself, including the important distinction: Instance members use $this, while static members use self:: or ClassName::.

What It Does

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

Before You Start

Read the input requirements before applying this pattern to production data.

Example 1: Basic Use

A static property is shared among instances in the same PHP request, not a durable database counter.

<?php
class VisitCounter {
    public static int $count = 0;
    public static function record(): int { return ++self::$count; }
}
for ($n = 0; $n < 2; $n++) { VisitCounter::record(); }
echo VisitCounter::$count;

Output from a successful local PHP 8.4 run:

2

Example 2: Checking Behavior

A static property is shared among instances in the same PHP request, not a durable database counter.

<?php
class VisitCounter {
    public static int $count = 0;
    public static function record(): int { return ++self::$count; }
}
for ($n = 0; $n < 3; $n++) { VisitCounter::record(); }
echo VisitCounter::$count;

Output from a successful local PHP 8.4 run:

3

Example 3: Practical Example

A static property is shared among instances in the same PHP request, not a durable database counter.

<?php
class VisitCounter {
    public static int $count = 0;
    public static function record(): int { return ++self::$count; }
}
for ($n = 0; $n < 4; $n++) { VisitCounter::record(); }
echo VisitCounter::$count;

Output from a successful local PHP 8.4 run:

4

Important Behavior and Edge Cases

Static mutable state can leak between calls and make tests order-dependent; prefer injected services for shared dependencies.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Static members belong to a class rather than a particular object instance.
• Static mutable state can leak between calls and make tests order-dependent; prefer injected services for shared dependencies.
• Instance members use $this, while static members use self:: or ClassName::.

Use Static Properties and Methods when its documented behavior matches the problem. Test the relevant edge cases in your own runtime before deploying it.