Portland WP Meetup - Hooks and Filters - Jan 08 2018 - Sample Hooks Plugin Code

plugin.php

<?php
/*
Plugin Name: Sample Plugin
Plugin URI: 
Description: Sample code for the Portland WordPress MeetUp Hooks and Filters Talk
Version: 1.0.0
Author: adamplabarge
Author URI: https://github.com/adamplabarge
Text Domain: sample-plugin
License: GPLv2
*/

add_action('genesis_before_header', 'demonstrate_call_user_func', 10);
function demonstrate_call_user_func() {
    load_pretend_hooks();
    load_sample_loop_and_filters();
}

function load_pretend_hooks() {
    $hooks = [
        'sample_header_hooks' => [
            'simple_print_func_a', 
            'simple_print_func_b'
        ]
    ];

    foreach($hooks['sample_header_hooks'] as $func) {
        echo "<p>" . call_user_func($func) . "</p>";
    }
}

function simple_print_func_a() {
    return "I\"m printing the letter A.";
}

function simple_print_func_b() {
    return "I\"m printing the letter B.";
}

function load_sample_loop_and_filters() {
    $args = [
        'post_type' => 'post',
    ];
    $q = new WP_Query($args);

    add_filter('the_permalink', 'alter_permalink');

    if ($q->have_posts()) :
        while ($q->have_posts()) : $q->the_post(); 
            echo '<p>' . the_permalink() . '</p>';
        endwhile;
    endif;

    remove_filter('the_permalink', 'alter_permalink');

    if ($q->have_posts()) :
        while ($q->have_posts()) : $q->the_post(); 
        echo '<p>' . the_permalink() . '</p>';
        endwhile;
    endif;
}

function alter_permalink($url) {
    return 'This is just a messages.';
    return 'http://allyourpermalink.com/are/belong/to/us';
}

//add_action('genesis_before_header', 'demonstrate_custom_actions', 15);
function demonstrate_custom_actions() {
    $name = 'bob';
    do_action('our_custom_action_hook', $name);

    $names = ['bob', 'jane', 'abigail', 'booker'];

    foreach($names as $name) {
        do_action('our_custom_action_hook', $name);
    }
}

add_action('our_custom_action_hook', 'our_custom_action_function');
function our_custom_action_function($_name) {
    echo ((strpos($_name, 'b') !== false) 
        ? apply_filters('our_data_filter', $_name) 
        : $_name) 
        . ' ';
}

add_filter('our_data_filter', 'our_capitalize_filter');
function our_capitalize_filter($_name) {
    return ucfirst($_name);
}

/**
 * Development Helpers
 */
//add_action('genesis_header','show_me_hook_info');
function show_me_hook_info() {
	$hook_name = 'genesis_header';
	global $wp_filter;
	dump($wp_filter[$hook_name]);
}

function dump( $var, $txt='' ) {
    print "<pre><b>$txt</b> = ";
    print_r( $var );
    print "</pre>";
}