https://github.com/sof3/php-ext-thisrc
PHP extension to get refcount of $this
https://github.com/sof3/php-ext-thisrc
Last synced: 10 months ago
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PHP extension to get refcount of $this
- Host: GitHub
- URL: https://github.com/sof3/php-ext-thisrc
- Owner: SOF3
- License: apache-2.0
- Created: 2020-05-04T14:10:35.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2020-08-16T08:16:14.000Z (over 5 years ago)
- Last Synced: 2025-01-25T10:41:19.119Z (12 months ago)
- Language: C
- Size: 17.6 KB
- Stars: 5
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# php-ext-thisrc
[](https://github.com/SOF3/serde-iter/actions?query=workflow%3ACI)
PHP extension to get refcount of `$this`.
This extension only adds one new function `thisrc() : int`.
It returns the refcount of `$this` when called from a class.
## Why require `$this` instead of arbitrary argument?
When the parameter is passed to another function,
the refcount increases.
This might cause confusing behaviour.
Calling the function without passing any references is more reliable.
## When is refcount information useful?
Consider an immutable value class with methods that return a modified version:
```php
class Foo {
private $inner;
public function __construct(int $inner) {
$this->inner = $inner;
}
public function plus(int $value) : Foo {
return new Foo($this->inner + $value);
}
public function times(int $value) : Foo {
return new Foo($this->inner - $value);
}
}
$three = new Foo(3);
$sixteen = $three->plus(5)->times(2);
```
This creases an intermediate object `Foo(8)` in the call chain.
If used in hot code,
this allocation could be optimized away:
```php
public function plus(int $value) : Foo {
if(thisrc() === 1) {
$this->inner += $value;
return $this;
} else {
return new Foo($this->inner + $value);
}
}
```
Then only one new `Foo` object is created in the call chain that creates `$sixteen`,
avoiding the allocation for the intermediate `Foo(8)`.