Integrate HTML-Code from other classes to own WP plugin - php

Question

I want to write a new Plugin in wordpress. My classes:
the plugin PHP-file:
<?php
/*
plugin-header (working)
*/
// Exit if accessed directly
defined('ABSPATH' || exit());
// Include classes
include('foo.php');
include('boo.php');
//add Init Hook
add_action('admin_menu','bohoo_admin');
function bohoo_admin() {
add_options_page('bohoo', 'someTitle', 'manage_options', __FILE__, 'createView');
}
function createView() {
$foo = new foo();
$boo = new boo();
return $foo->createFooDiv() . $boo->createBooDiv();
}
?>
My foo.php:
<?php
class foo {
public function __construct() {
}
public function createFooDiv() {
return '<div><h2>Hi</h2></div>';
}
}
?>
My boo.php:
<?php
class boo {
public function __construct() {
}
public function createBooDiv() {
return '<div> test </div>';
}
}
?>
Now what I basically tried is: The HTML-code should be in two different files and these should be concatenated and displayed (of course).
The way I understood integrating plugins in WP:
With the add_options_page-method you specify where your plugin is shown and what code is displayed. For the code you use the last argument (in this case the createView-method. This works so far if my createView() in my plugin PHP-file looks like this:
function createView() {
//include HTML-Code directly
?>
<h1>Hello World</h1>
<?php
}
?>
What happens when I include the boo.php and foo.php files instead of including the HTML-Code directly is nothing (So nothing is displayed and there is on error aswell). I am not sure what I am doing wrong, I also tried playing around with the HTML-Code in the return-statements of BOO and FOO, but that did not help either. What am I doing wrong? Or is it simply not possible to do it that way?

Answer 1

You need to print/echo your html content. Change createView to this:
function createView() {
$foo = new foo();
$boo = new boo();
echo $foo->createFooDiv() . $boo->createBooDiv();
}
That's how it's done in the add_options docs page.
And basically when you use php closing and opening tags:
?>
<h1>Some html</h1>
<?php
It's equivalent to printing the content in between:
echo '<h1>Some html</h1>';