woocommerce_product_loop_start │ filter-hook │ WC 1.0

Usage

add_filter( 'woocommerce_product_loop_start', 'wp_kama_woocommerce_product_loop_start_filter' );

/**
 * Function for `woocommerce_product_loop_start` filter-hook.
 * 
 * @param  $ob_get_clean 
 *
 * @return 
 */
function wp_kama_woocommerce_product_loop_start_filter( $ob_get_clean ){

	// filter...
	return $ob_get_clean;
}

$ob_get_clean

-

Where the hook is called

$loop_start = apply_filters( 'woocommerce_product_loop_start', ob_get_clean() );

Where the hook is used in WooCommerce

add_filter( 'woocommerce_product_loop_start', 'woocommerce_maybe_show_product_subcategories' );