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<?php
/**
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
*/
/**
* Construct objects from configuration instructions.
*
* @author Bryan Davis <bd808@wikimedia.org>
* @copyright © 2014 Bryan Davis and Wikimedia Foundation.
*/
class ObjectFactory {
/**
* Instantiate an object based on a specification array.
*
* The specification array must contain a 'class' key with string value
* that specifies the class name to instantiate or a 'factory' key with
* a callable (is_callable() === true). It can optionally contain
* an 'args' key that provides arguments to pass to the
* constructor/callable.
*
* Object construction using a specification having both 'class' and
* 'args' members will call the constructor of the class using
* ReflectionClass::newInstanceArgs. The use of ReflectionClass carries
* a performance penalty and should not be used to create large numbers of
* objects. If this is needed, consider introducing a factory method that
* can be called via call_user_func_array() instead.
*
* Values in the arguments collection which are Closure instances will be
* expanded by invoking them with no arguments before passing the
* resulting value on to the constructor/callable. This can be used to
* pass DatabaseBase instances or other live objects to the
* constructor/callable. This behavior can be suppressed by adding
* closure_expansion => false to the specification.
*
* The specification may also contain a 'calls' key that describes method
* calls to make on the newly created object before returning it. This
* pattern is often known as "setter injection". The value of this key is
* expected to be an associative array with method names as keys and
* argument lists as values. The argument list will be expanded (or not)
* in the same way as the 'args' key for the main object.
*
* @param array $spec Object specification
* @return object
* @throws InvalidArgumentException when object specification does not
* contain 'class' or 'factory' keys
* @throws ReflectionException when 'args' are supplied and 'class'
* constructor is non-public or non-existent
*/
public static function getObjectFromSpec( $spec ) {
$args = isset( $spec['args'] ) ? $spec['args'] : array();
$expandArgs = !isset( $spec['closure_expansion'] ) ||
$spec['closure_expansion'] === true;
if ( $expandArgs ) {
$args = static::expandClosures( $args );
}
if ( isset( $spec['class'] ) ) {
$clazz = $spec['class'];
if ( !$args ) {
$obj = new $clazz();
} else {
$ref = new ReflectionClass( $clazz );
$obj = $ref->newInstanceArgs( $args );
}
} elseif ( isset( $spec['factory'] ) ) {
$obj = call_user_func_array( $spec['factory'], $args );
} else {
throw new InvalidArgumentException(
'Provided specification lacks both factory and class parameters.'
);
}
if ( isset( $spec['calls'] ) && is_array( $spec['calls'] ) ) {
// Call additional methods on the newly created object
foreach ( $spec['calls'] as $method => $margs ) {
if ( $expandArgs ) {
$margs = static::expandClosures( $margs );
}
call_user_func_array( array( $obj, $method ), $margs );
}
}
return $obj;
}
/**
* Iterate a list and call any closures it contains.
*
* @param array $list List of things
* @return array List with any Closures replaced with their output
*/
protected static function expandClosures( $list ) {
return array_map( function ( $value ) {
if ( is_object( $value ) && $value instanceof Closure ) {
// If $value is a Closure, call it.
return $value();
} else {
return $value;
}
}, $list );
}
}
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