Where to Fork Recent Posts Widget? - wordpress

Question

I am trying to create a custom recent posts widget by forking the default WordPress widget. I understand you shouldn;t hack core code, but rather fork the original widget and then register it in the functions file.
The only thing is, I don't know where to fork. I've found the default widget and I know that I'd register the widget in my theme's functions.php file, I just don't know where to save the code I'm forking. For example, do I save it as a plugin in the plugins folder, etc.?
Here's the default WordPress code:
/**
* Recent_Posts widget class
*
* #since 2.8.0
*/
class WP_Widget_Recent_Posts extends WP_Widget {
function __construct() {
$widget_ops = array('classname' => 'widget_recent_entries', 'description' => __( "Your site’s most recent Posts.") );
parent::__construct('recent-posts', __('Recent Posts'), $widget_ops);
$this->alt_option_name = 'widget_recent_entries';
add_action( 'save_post', array($this, 'flush_widget_cache') );
add_action( 'deleted_post', array($this, 'flush_widget_cache') );
add_action( 'switch_theme', array($this, 'flush_widget_cache') );
}
function widget($args, $instance) {
$cache = array();
if ( ! $this->is_preview() ) {
$cache = wp_cache_get( 'widget_recent_posts', 'widget' );
}
if ( ! is_array( $cache ) ) {
$cache = array();
}
if ( ! isset( $args['widget_id'] ) ) {
$args['widget_id'] = $this->id;
}
if ( isset( $cache[ $args['widget_id'] ] ) ) {
echo $cache[ $args['widget_id'] ];
return;
}
ob_start();
extract($args);
$title = ( ! empty( $instance['title'] ) ) ? $instance['title'] : __( 'Recent Posts' );
/** This filter is documented in wp-includes/default-widgets.php */
$title = apply_filters( 'widget_title', $title, $instance, $this->id_base );
$number = ( ! empty( $instance['number'] ) ) ? absint( $instance['number'] ) : 5;
if ( ! $number )
$number = 5;
$show_date = isset( $instance['show_date'] ) ? $instance['show_date'] : false;
/**
* Filter the arguments for the Recent Posts widget.
*
* #since 3.4.0
*
* #see WP_Query::get_posts()
*
* #param array $args An array of arguments used to retrieve the recent posts.
*/
$r = new WP_Query( apply_filters( 'widget_posts_args', array(
'posts_per_page' => $number,
'no_found_rows' => true,
'post_status' => 'publish',
'ignore_sticky_posts' => true
) ) );
if ($r->have_posts()) :
?>
<?php echo $before_widget; ?>
<?php if ( $title ) echo $before_title . $title . $after_title; ?>
<ul>
<?php while ( $r->have_posts() ) : $r->the_post(); ?>
<li>
<?php get_the_title() ? the_title() : the_ID(); ?>
<?php if ( $show_date ) : ?>
<span class="post-date"><?php echo get_the_date(); ?></span>
<?php endif; ?>
</li>
<?php endwhile; ?>
</ul>
<?php echo $after_widget; ?>
<?php
// Reset the global $the_post as this query will have stomped on it
wp_reset_postdata();
endif;
if ( ! $this->is_preview() ) {
$cache[ $args['widget_id'] ] = ob_get_flush();
wp_cache_set( 'widget_recent_posts', $cache, 'widget' );
} else {
ob_end_flush();
}
}
function update( $new_instance, $old_instance ) {
$instance = $old_instance;
$instance['title'] = strip_tags($new_instance['title']);
$instance['number'] = (int) $new_instance['number'];
$instance['show_date'] = isset( $new_instance['show_date'] ) ? (bool) $new_instance['show_date'] : false;
$this->flush_widget_cache();
$alloptions = wp_cache_get( 'alloptions', 'options' );
if ( isset($alloptions['widget_recent_entries']) )
delete_option('widget_recent_entries');
return $instance;
}
function flush_widget_cache() {
wp_cache_delete('widget_recent_posts', 'widget');
}
function form( $instance ) {
$title = isset( $instance['title'] ) ? esc_attr( $instance['title'] ) : '';
$number = isset( $instance['number'] ) ? absint( $instance['number'] ) : 5;
$show_date = isset( $instance['show_date'] ) ? (bool) $instance['show_date'] : false;
?>
<p><label for="<?php echo $this->get_field_id( 'title' ); ?>"><?php _e( 'Title:' ); ?></label>
<input class="widefat" id="<?php echo $this->get_field_id( 'title' ); ?>" name="<?php echo $this->get_field_name( 'title' ); ?>" type="text" value="<?php echo $title; ?>" /></p>
<p><label for="<?php echo $this->get_field_id( 'number' ); ?>"><?php _e( 'Number of posts to show:' ); ?></label>
<input id="<?php echo $this->get_field_id( 'number' ); ?>" name="<?php echo $this->get_field_name( 'number' ); ?>" type="text" value="<?php echo $number; ?>" size="3" /></p>
<p><input class="checkbox" type="checkbox" <?php checked( $show_date ); ?> id="<?php echo $this->get_field_id( 'show_date' ); ?>" name="<?php echo $this->get_field_name( 'show_date' ); ?>" />
<label for="<?php echo $this->get_field_id( 'show_date' ); ?>"><?php _e( 'Display post date?' ); ?></label></p>
<?php
}
}

Answer 1

Create a folder in Plugins and save it in there.
You don't have to create a new folder, but I would advise it just to keep the project clean.
More info here : http://codex.wordpress.org/Writing_a_Plugin