WordPress: Handling default data with option arrays

<?php

/*
    Mini guide to setting/handling defaults when using arrays with WordPress options
    Covers restoring defaults, safely adding new data, and wiping data.

    Template usage for array options: <?php $options = get_option('muffin_options'); echo $options['logo_text']; ?>
*/

add_action( 'admin_init', 'muffin_options_init' );

function muffin_options_init() {
    register_setting( 'muffin_options', 'muffin_options' );
    muffin_options_defaults();
}

function muffin_options_defaults() {

    // Get the options
    $muffin_options = get_option('muffin_options');

    // If there are no options, create an empty array to assist with the default options array handling below
    if(empty($muffin_options)) $muffin_options = [];

    $muffin_options_default['logo_text'] = 'Hello World';
    $muffin_options_default['post_style'] = 'excerpts';
    $muffin_options_default['default_featuredimage'] = get_template_directory_uri().'/images/posts/featuredimage-default.png';
    $muffin_options_default['nav_style'] = 'right';
    $muffin_options_default['blog_title'] = 'Latest News';

    /*
        Comment or uncomment the code below. The currently uncommented is generally the only code you'll
        need to use. The other available choices can be very helpful too though.
    */

    # [1] Create 'muffin_options', using the defaults (the data listed above)
    # [?] Basically useless to us - use [4] to set up your data instead
    // add_option('muffin_options', $muffin_options_default);

    # [2] Add any new default data, but don't overwrite anything.
    # [?] Use to add new data while preserving user changes
    $muffin_options = array_merge($muffin_options_default,$muffin_options);
    update_option('muffin_options', $muffin_options);

    # [3] Restore defaults, but KEEP all other data
    # [?] Use to both add new data, and overwrite user changes to default data. Good with a 'Restore Defaults' button
    // $muffin_options = array_merge($muffin_options,$muffin_options_default);
    // update_option('muffin_options', $muffin_options);

    # [4] Restore defaults, and WIPE all other data
    # [?] Use to both replace all option data with defaults, and clear all user data. Use for/to emulate fresh installs
    // update_option('muffin_options', $muffin_options_default);

    # [5] Delete the option entirely
    # [?] Use to remove the option from the  database entirely- good for resets, testing and cleanup
    // delete_option('muffin_options');
}




//  BONUS! This tiny function is a huge help when using options.

function issetor(&$var, $default=false) {
    return isset($var) ? $var : $default;
}

/*
    It's a shortcut to saying "if this variable has a value set, echo that value, otherwise, return false".

        Usage: <?php echo issetor($options['name']); ?>

    You can pass a second argument too. This will be returned if the variable doesn't have a value set.

        Usage: <?php echo issetor($options['name'], 'Joe Bloggs'); ?>

    The function helps prevent errors, and makes your code shorter. Here's how to use it with radio buttons:

        <label>
            <input type='radio' name='muffin_options[post_style]' <?php checked( issetor($options['post_style']),'excerpts' ); ?> value='excerpts'>
            Show Excerpts
        </label> <br />
        <label>
            <input type='radio' name='muffin_options[post_style]' <?php checked( issetor($options['post_style']),'fullposts' ); ?> value='fullposts'>
            Show Full Posts
        </label>

*/

?>