[WordPress] Using Custom Filters with Shortcodes

00-a-simple-example.php

<?php

namespace Acme;

add_shortcode('a_simple_example', __NAMESPACE__ . '\\aSimpleExample');
/**
 * Replaces [a_simple_example] short code with the text "This is the result of an example shortcode."
 * whenever the shortcode is placed in a post or page.
 */
function aSimpleExample()
{
  return 'This is the result of an example shortcode.';
}

01-a-simple-filter.php

<?php

namespace Acme;

add_filter('custom_shortcode_example', __NAMESPACE__ . '\\aSimpleShortcodeFilter');
/**
 * Replaces [a simple example] short code with the text "This is the result of an example shortcode."
 * whenever the shortcode is placed in a post or page.
 *
 * @param string $input the input to filter.
 *
 * @return string       the result of the filter running on the input
 */
function aSimpleShortcodeFilter(string $input): string
{
  return str_ireplace(
    'an example shortcode.',
    'a filtered shortcode',
    $input
  );
}

02-a-filtered-shortcode.php

<?php

namespace Acme;

add_shortcode('a_simple_example', __NAMESPACE__ . '\\aSimpleExample');
/**
 * Replaces [a_simple_example] short code with the text "This is the result of an example shortcode."
 * whenever the shortcode is placed in a post or page.
 */
function aSimpleExample()
{
  return apply_filters('custom_shortcode_example', 'This is the result of an example shortcode.');
}