PHP: WordPress - Custom Excerpt Length Template Part

excerpt.php

<?php
/**
 * Custom Excerpt
 * 
 * Needs $word_count set from the template it's being called from
 *
 * Template Usage:
 *
 * $word_count = 60;
 * get_template_part( 'parts/excerpt' );
 *
 */
global $word_count;

// sets a default word count fallback
if ( empty( $word_count ) ) $word_count = 36;

$text = get_the_content();
$excerpt = get_the_excerpt();

$custom_excerpt = custom_trim_words( $text, $num_words = $word_count, $more = '... ' );

// Echo custom excerpt if the excerpt is empty
if ( ! empty( $post->post_excerpt ) ) {
    echo $excerpt;
} else {
    echo $custom_excerpt;
}