Return to Answer

First thing that pops in the eye is the unindented code, most [IDE][1]s do this automatically for us. That's fundamental for everyone's sanity, yours and whomever reads your code.

And you are missing two things from [add_meta_box()][2] parameters that will make the code reusable:

• $metaboxes is the reusable source, just add another item and a new metabox is created.
• save_post receives 2 arguments, $post_id and $post_object.
• I prefer to put all hook declarations at the beginning, as it gives a general panorama of all functions below.
• Use of [printf()][3] to build complex HTML blocks.

Suggestion:
Instead of one Meta Box for each piece of information, I think it's better UX to have a single box for your plugin/feature and add the form fields there. [1]: https://stackoverflow.com/tags/ide/info [2]: https://codex.wordpress.org/Function_Reference/add_meta_box [3]: http://php.net/manual/en/function.printf.php

First thing that pops in the eye is the unindented code, most IDE s do this automatically for us. That's fundamental for everyone's sanity, yours and whomever reads your code.

And you are missing two things from add_meta_box() parameters that will make the code reusable:

• $metaboxes is the reusable source, just add another item and a new metabox is created.
• save_post receives 2 arguments, $post_id and $post_object.
• I prefer to put all hook declarations at the beginning, as it gives a general panorama of all functions below.
• Use of printf() to build complex HTML blocks.

Suggestion:
Instead of one Meta Box for each piece of information, I think it's better UX to have a single box for your plugin/feature and add the form fields there.

Suggestion:
Instead of one Meta Box for each piece of information, I think it's better UX to have a single box for your plugin/feature and add the form fields there. [1]: http://stackoverflow.com/tags/ide/info [2]: https://codex.wordpress.org/Function_Reference/add_meta_box [3]: http://php.net/manual/en/function.printf.php

Suggestion:
Instead of one Meta Box for each piece of information, I think it's better UX to have a single box for your plugin/feature and add the form fields there. [1]: https://stackoverflow.com/tags/ide/info [2]: https://codex.wordpress.org/Function_Reference/add_meta_box [3]: http://php.net/manual/en/function.printf.php

First thing that pops in the eye is the unindented code, most IDE s do this automatically for us. That's fundamental for everyone's sanity, yours and whomever reads your code.

And you are missing two things from add_meta_box() parameters that will make the code reusable:

• $metaboxes is the reusable source, just add another item and a new metabox is created.
• save_post receives 2 arguments, $post_id and $post_object.
• I prefer to put all hook declarations at the beginning, as it gives a general panorama of all functions below.
• Use of printf() to build complex HTML blocks.

add_action( 'add_meta_boxes', 'wp_cat_map_add_meta_box' );
add_action( 'save_post', 'wp_cat_map_data', 10, 2 );
function wp_cat_map_add_meta_box() {
 $screens = array( 'post', 'page' );
 $metaboxes = array(
 'map_lat' => array(
 'label' => 'wp_cat_map_lat',
 'title' => __( 'Add Latitude', 'wp_cat_map' ),
 'description' => __( 'Latitude', 'wp_cat_map' ),
 'name' => 'wp_cat_map_lat',
 'post_meta' => '_wp_cat_map_lat'
 ),
 'map_long' => array(
 'label' => 'wp_cat_map_long',
 'title' => __( 'Add Longitude', 'wp_cat_map' ),
 'description' => __( 'Longitude', 'wp_cat_map' ),
 'name' => 'wp_cat_map_long' ,
 'post_meta' => '_wp_cat_map_long' 
 )
 );
 foreach ( $metaboxes as $meta_id => $meta_cont ) {
 add_meta_box( 
 $meta_id, 
 $meta_cont['title'], 
 'wp_cat_map_callback', 
 $screens, 
 'advanced', 
 'default', 
 $meta_cont 
 );
 }
}
function wp_cat_map_callback( $post, $post_object ) {
 /* Inspect the object */
 // printf( '<pre><code>%s</code></pre>', print_r( $post_object, true ) );
 wp_nonce_field( 'wp_cat_map_data', 'wp_cat_map_nonce' );
 $value = get_post_meta( $post->ID, $post_object['args']['post_meta'], true );
 printf( 
 '<label for="%s">',
 $post_object['args']['label']
 );
  echo $post_object['args']['description'];
 echo '</label> ';
 printf(
 '<input type="text" id="%s" name="%s" value="%s"/>',
 $post_object['args']['label'],
 $post_object['args']['post_meta'],
 esc_attr( $value )
 );
}
function wp_cat_map_data( $post_id, $post_object ) { /* code */ }

Class Code_Review_111019 {
 private $screens;
 private $metaboxes;
 
 public function __construct( $screens, $metaboxes ) {
 $this->screens = $screens;
 $this->metaboxes = $metaboxes;
 /* Start everything at a safer point */
 add_action( 'plugins_loaded', array( $this, 'start_up' ) );
 }
 
 public function start_up() {
 add_action( 'add_meta_boxes', array( $this, 'add_meta_box' ) );
 add_action( 'save_post', array( $this, 'save_post' ), 10, 2 ); 
 }
 
 public function add_meta_box() {
 foreach ( $this->metaboxes as $meta_id => $meta_cont ) {
 add_meta_box( 
 $meta_id, 
 $meta_cont['title'], 
 array( $this, 'build_metabox' ), 
 $this->screens, 
 'advanced', 
 'default', 
 $meta_cont 
 );
 }
 }
 public function build_metabox( $post, $post_object ) {
 wp_nonce_field( 'wp_cat_map_data', 'wp_cat_map_nonce' );
 $value = get_post_meta( $post->ID, $post_object['args']['post_meta'], true );
 printf( 
 '<label for="%s">',
 $post_object['args']['label']
 );
  echo $post_object['args']['description'];
 echo '</label> ';
 printf(
 '<input type="text" id="%s" name="%s" value="%s"/>',
 $post_object['args']['label'],
 $post_object['args']['post_meta'],
 esc_attr( $value )
 );
 }
 /* FOR DEBUGGING PURPOSES ONLY */
 public function save_post( $post_id, $post_object ) { 
 printf( '<pre><code>%s</code></pre>', print_r( $post_object, true ) );
 printf( '<pre><code>%s</code></pre>', print_r( $this->metaboxes, true ) );
 printf( '<pre><code>%s</code></pre>', print_r( $_POST, true ) );
 die();
 }
}
$Code_Review_111019 = new Code_Review_111019(
 /* Screens */
 array( 'post', 'page', 'panorama' ),
 /* Metaboxes */
 array(
 'map_lat' => array(
 'label' => 'wp_cat_map_lat',
 'title' => __( 'Add Latitude', 'wp_cat_map' ),
 'description' => __( 'Latitude', 'wp_cat_map' ),
 'name' => 'wp_cat_map_lat',
 'post_meta' => '_wp_cat_map_lat'
 ),
 'map_long' => array(
 'label' => 'wp_cat_map_long',
 'title' => __( 'Add Longitude', 'wp_cat_map' ),
 'description' => __( 'Longitude', 'wp_cat_map' ),
 'name' => 'wp_cat_map_long' ,
 'post_meta' => '_wp_cat_map_long' 
 ),
 'map_zoom' => array(
 'label' => 'wp_cat_map_zoom',
 'title' => __( 'Add Zoom', 'wp_cat_map' ),
 'description' => __( 'Zoom', 'wp_cat_map' ),
 'name' => 'wp_cat_map_zoom' ,
 'post_meta' => '_wp_cat_map_zoom' 
 ) 
 )
);

First thing that pops in the eye is the unindented code, most [IDE][1]s do this automatically for us. That's fundamental for everyone's sanity, yours and whomever reads your code.

And you are missing two things from [add_meta_box()][2] parameters that will make the code reusable:

• $metaboxes is the reusable source, just add another item and a new metabox is created.
• save_post receives 2 arguments, $post_id and $post_object.
• I prefer to put all hook declarations at the beginning, as it gives a general panorama of all functions below.
• Use of [printf()][3] to build complex HTML blocks.

add_action( 'add_meta_boxes', 'wp_cat_map_add_meta_box' );
add_action( 'save_post', 'wp_cat_map_data', 10, 2 );
function wp_cat_map_add_meta_box() {
 /* Our configuration vars */
 $screens = array( 'post', 'page' );
 $metaboxes = array(
 'map_lat' => array(
 'label' => 'wp_cat_map_lat',
 'title' => __( 'Add Latitude', 'wp_cat_map' ),
 'description' => __( 'Latitude', 'wp_cat_map' ),
 'name' => 'wp_cat_map_lat',
 'post_meta' => '_wp_cat_map_lat'
 ),
 'map_long' => array(
 'label' => 'wp_cat_map_long',
 'title' => __( 'Add Longitude', 'wp_cat_map' ),
 'description' => __( 'Longitude', 'wp_cat_map' ),
 'name' => 'wp_cat_map_long' ,
 'post_meta' => '_wp_cat_map_long' 
 )
 );
 foreach ( $metaboxes as $meta_id => $meta_cont ) {
 add_meta_box( 
 $meta_id, 
 $meta_cont['title'], 
 'wp_cat_map_callback', 
 $screens, 
 'advanced', 
 'default', 
 $meta_cont 
 );
 }
}
function wp_cat_map_callback( $post, $post_object ) {
 /* Inspect the object */
 // printf( '<pre><code>%s</code></pre>', print_r( $post_object, true ) );
 wp_nonce_field( 'wp_cat_map_data', 'wp_cat_map_nonce' );
 $value = get_post_meta( $post->ID, $post_object['args']['post_meta'], true );
 printf( 
 '<label for="%s">%s</label>',
 $post_object['args']['label'],
 $post_object['args']['description'];
 );
 printf(
 '<input type="text" id="%s" name="%s" value="%s"/>',
 $post_object['args']['label'],
 $post_object['args']['post_meta'],
 esc_attr( $value )
 );
}
function wp_cat_map_data( $post_id, $post_object ) { /* code */ }

Class Code_Review_111019 {
 /* Class properties, available to all methods */
 private $screens;
 private $metaboxes;
 
 public function __construct( $screens, $metaboxes ) {
 /* Set properties when instantiating */
 $this->screens = $screens;
 $this->metaboxes = $metaboxes;
 /* Start our hooks at a safer point */
 add_action( 'plugins_loaded', array( $this, 'start_up' ) );
 }
 
 public function start_up() {
 /* Inside classes we don't need unique prefixes or names for the callbacks, better yet, they can be literal */
 add_action( 'add_meta_boxes', array( $this, 'add_meta_boxes' ) );
 add_action( 'save_post', array( $this, 'save_post' ), 10, 2 ); 
 }
 
 public function add_meta_boxes() {
 foreach ( $this->metaboxes as $meta_id => $meta_cont ) {
 add_meta_box( 
 $meta_id, 
 $meta_cont['title'], 
 array( $this, 'build_metabox' ), 
 $this->screens, 
 'advanced', 
 'default', 
 $meta_cont 
 );
 }
 }
 public function build_metabox( $post, $post_object ) {
 wp_nonce_field( 'wp_cat_map_data', 'wp_cat_map_nonce' );
 $value = get_post_meta( $post->ID, $post_object['args']['post_meta'], true );
 printf( 
 '<label for="%s">%s</label>',
 $post_object['args']['label'],
 $post_object['args']['description']
 );
 printf(
 '<input type="text" id="%s" name="%s" value="%s"/>',
 $post_object['args']['label'],
 $post_object['args']['post_meta'],
 esc_attr( $value )
 );
 }
 /* NO CHECKS OR SECURITY WHATSOEVER, FOR DEBUGGING PURPOSES ONLY */
 public function save_post( $post_id, $post_object ) { 
 foreach( $this->metaboxes as $mbox ){
  if( isset( $_POST[ $mbox['post_meta'] ] ) ) {
  update_post_meta( $post_id, $mbox['post_meta'], $_POST[ $mbox['post_meta'] ] );
  }
 }
 }
}
$Code_Review_111019 = new Code_Review_111019(
 /* Screens */
 array( 'post', 'page', 'portfolio' ),
 /* Metaboxes */
 array(
 'map_lat' => array(
 'label' => 'wp_cat_map_lat',
 'title' => __( 'Add Latitude', 'wp_cat_map' ),
 'description' => __( 'Latitude', 'wp_cat_map' ),
 'name' => 'wp_cat_map_lat',
 'post_meta' => '_wp_cat_map_lat'
 ),
 'map_long' => array(
 'label' => 'wp_cat_map_long',
 'title' => __( 'Add Longitude', 'wp_cat_map' ),
 'description' => __( 'Longitude', 'wp_cat_map' ),
 'name' => 'wp_cat_map_long' ,
 'post_meta' => '_wp_cat_map_long' 
 ),
 'map_zoom' => array(
 'label' => 'wp_cat_map_zoom',
 'title' => __( 'Add Zoom', 'wp_cat_map' ),
 'description' => __( 'Zoom', 'wp_cat_map' ),
 'name' => 'wp_cat_map_zoom' ,
 'post_meta' => '_wp_cat_map_zoom' 
 ) 
 )
);

Suggestion:
Instead of one Meta Box for each piece of information, I think it's better UX to have a single box for your plugin/feature and add the form fields there. [1]: http://stackoverflow.com/tags/ide/info [2]: https://codex.wordpress.org/Function_Reference/add_meta_box [3]: http://php.net/manual/en/function.printf.php