Introduction to WordPress Filters

gistfile1.php

<?php

// Define our Custom Post Type
function dwwp_register_post_type() {
	//Add a filter to our $singular variable.
	$singular = apply_filters( 'dwwp_label_single', 'Book' );
	//Add a filter to our $plural variable.
	$plural = apply_filters( 'dwwp_label_plural', 'Books' );

	$labels = array(
		'name' 			=> $plural,
		'singular_name' 	=> $singular,
		'add_new' 		=> 'Add New',
		'add_new_item'  	=> 'Add New ' . $singular,
		'edit'		        => 'Edit',
		'edit_item'	        => 'Edit ' . $singular,
		'new_item'	        => 'New ' . $singular,
		'view' 			=> 'View ' . $singular,
		'view_item' 		=> 'View ' . $singular,
		'search_term'   	=> 'Search ' . $plural,
		'parent' 		=> 'Parent ' . $singular,
		'not_found' 		=> 'No ' . $plural .' found',
		'not_found_in_trash' 	=> 'No ' . $plural .' in Trash'
	);
	//Add a filter to our cpt's $args variable.
	$args = apply_filters( 'dwwp_post_type_args',array(
		'labels'             => $labels,
	        'public'             => true,
	        'publicly_queryable' => true,
	        'show_ui'            => true,
	        'show_in_menu'       => true,
	        'menu_icon'          => 'dashicons-businessman',
	        'query_var'          => true,
	        'rewrite'            => array( 'slug' => $plural ),
	        'capability_type'    => 'post',
	        'has_archive'        => true,
	        'hierarchical'       => false,
	        'menu_position'      => 10,
	        'supports'           => array( 'title', 'editor', 'author', 'custom-fields' )
	) );
	register_post_type( $singular, $args );
}

add_action( 'init', 'dwwp_register_post_type' );

//Code to be placed on the theme's functions.php file. This code will modify the CPT icon.
function dwwp_alter_books_icon( $args ) {

	$args['menu_icon'] = 'dashicons-book-alt';
	return $args;

}
add_filter( 'dwwp_post_type_args', 'dwwp_alter_books_icon' );

//Code to be placed on the theme's functions.php file. This code will modify the CPT's plural name.
function dwwp_cpt_plural( $plural ) {
	$plural = 'Bookz';
	return $plural;
}
add_filter ( 'dwwp_label_plural', 'dwwp_cpt_plural' );

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