I cannot shorten title posts

Hello,

I usually use this function to shorten my titles:

function the_title_shorten($len,$rep='...') {
	$title = the_title('','',false);
	$shortened_title = textLimit($title, $len, $rep);
	print $shortened_title;
}

//shorten without cutting full words (Thank You Serzh 'https://us2.php.net/manual/en/function.substr.php#83585')
function textLimit($string, $length, $replacer) {
	if(strlen($string) > $length)
	return (preg_match('/^(.*)\W.*$/', substr($string, 0, $length+1), $matches) ? $matches[1] : substr($string, 0, $length)) . $replacer;
	return $string;
}

However, I have one plugin which has this line of code:
<a href='" . get_permalink($post->ID) . "' title='". esc_attr($post->post_title) ."'>" . esc_html($post->post_title) ."</a>

How can I shorten the title of esc_html($post->post_title) ?

Thanks for your help !