Assert is a PHP library that provides an alternative to PHP's assert() that allows for a simple and reliable way to check preconditions and postconditions in PHP code. It was proposed as a MediaWiki RFC, but is completely generic and can be used by any PHP program or library.

Usage

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The Assert class provides several static methods for checking various kinds of assertions. The most common kind is to check the type of a parameter, typically in a constructor or a setter method:

use Wikimedia\Assert\Assert;

function setFoo( $foo ) {
    Assert::parameterType( 'integer', $foo, 'foo' );
    Assert::parameter( $foo > 0, 'foo', 'must be greater than 0' );
}

function __construct( $bar, array $bazz ) {
    Assert::parameterType( 'Me\MyApp\SomeClass', $bar );
    Assert::parameterElementType( 'int', $bazz );
}

Checking parameters, or other assertions such as pre- or postconditions, is not recommended for performance critical regions of the code, since evaluating expressions and calling the assertion functions costs time.

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