How to explode single string IF it’s used in shortcode

I have a shortcode that works to display posts from specific categories, or a single post based on the post slug. I’m having trouble figuring out how to get it to display multiple posts based on their slugs though. I know I need to use explode, but I can’t seem to get it right.

Here’s the current working code:

add_shortcode( 'latest_post', 'latest_post_query_shortcode' ); function latest_post_query_shortcode(  $  atts ) {     ob_start();     $  atts = shortcode_atts( array(             'posts_per_page' => '',             'category' => '',             'offset' => '',             'post' => '',     ), $  atts );      $  args = array(             'post_type'     => 'post',             'post_status'   => 'publish',             'posts_per_page'=> $  atts['posts_per_page'],             'offset'             => $  atts['offset'],         );              // Add category if not empty     if ( ! empty ( $  atts['category'] ) ) {         $  args['tax_query']  = array(                  array(                     'taxonomy'  => 'category',                     'field'     => 'slug',                     'terms' => $  atts['category'],                 ),              );           }          // Add post if not empty     if ( ! empty ( $  atts['post'] ) ) {         $  args['name']  = $  atts['post'];     }         $  string = '';              // The Query     $  query = new WP_Query( $  args );       // The Loop     if ( $  query->have_posts() ) { ?>         <section class="recent-posts clear">         <?php while ( $  query->have_posts() ) : $  query->the_post() ; ?>             <article id="post-<?php the_ID(); ?>" <?php post_class( 'left' ); ?>>                  <?  echo '<a href="' . get_permalink( $  _post->ID ) . '" title="' . esc_attr( $  _post->post_title ) . '">';                     echo get_the_post_thumbnail( $  _post->ID, 'large' );                     echo '</a>';                     echo '<h2><a href="' . get_permalink( $  _post->ID ) . '" title="' . esc_attr( $  _post->post_title ) . '">';                     echo get_the_title( $  _post->ID);                     echo '</a></h2>';                  ?>             </article>         <?php endwhile;          wp_reset_postdata();?>           </section>                   <?php          $  clean = ob_get_clean();         return $  clean;           } } 

I tried adding:

'name' => explode( ', ', $  post), 

inside

$  args = array( 

but that didn’t return anything when I tried specifying two slugs, for example: [latest_post post="almond-cake, coconut-pie"] (If I use either one of those, it works, but not both.)

Additionally once I added the explode, it game me this warning everywhere else the shortcode was used:

Warning: trim() expects parameter 1 to be string, array given…