Lazy Property
This small library aims at providing a very simple and efficient loading of lazy properties, (*1)
, (*2)
Abandoned
Starting with PHP 8.3, dynamic properties are no longer allowed "out of the box".
While it is still possible to have dynamic properties via explicit declaration (the #[\AllowDynamicProperties] attribute), the approach
of this package is no longer to be considered safe nor efficient long-term., (*3)
Based on that, this package is deprecated and abandoned: please use traditional PHP arrays instead., (*4)
Installation
The suggested installation method is via composer:, (*5)
composer require ocramius/lazy-property
Use case
In many cases where lazy-initialization of private/protected properties is necessary,
many people write classes that look like following:, (*6)
class SomeService
{
protected $dependency;
public function doWork()
{
$this->getDependency()->delegateWork();
}
protected function getDependency()
{
return $this->dependency ?: $this->dependency = get_dependency_somehow();
}
}
This is problematic because implementors and people subclassing SomeService will eventually
write:, (*7)
class SomethingElse extends SomeService
{
public function doOtherWork()
{
$this->dependency->doMoreWork();
}
}
This can work only if SomeService#getDependency() was called at least once upfront (which
may well be under certain circumstances), and therefore is a cause of bugs/headaches/suicides/etc., (*8)
In order to avoid this problem, the implementor of SomeService that is also exposing
its protected $dependency property may just use LazyProperty\LazyPropertiesTrait to fix the problem:, (*9)
#[\AllowDynamicProperties]
class SomeService
{
use \LazyProperty\LazyPropertiesTrait;
protected MyDependency $dependency;
public function __construct()
{
$this->initLazyProperties(['dependency']);
}
public function doWork()
{
// look ma! no getter!
$this->dependency->delegateWork();
}
protected function getDependency()
{
return $this->dependency ?: $this->dependency = get_dependency_somehow();
}
}
With this, any access to SomeService#$dependency will cause a call to
SomeService#getDependency() if the property was not already initialized., (*10)
class SomethingElse extends SomeService
{
public function doOtherWork()
{
// always works
$this->dependency->doMoreWork();
}
}
Please note that a getter is required in order for the property to be lazy., (*11)
Using LazyProperty\LazyPropertiesTrait allows to speed up applications where a massive
amount of getter calls is going on in private/protected scope.
There is some minor overhead in calling SomeService#initLazyProperties(), as well as in
the first property access, but it should be negligible., (*12)
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