Customize group_title with callback

Alright, I’ve hacked it up myself.

I changed the
In CMB2_Field.php, I changed the replace_hash function to be:

public function replace_hash($value)
{
    if (!$this->options('group_title_callback')) {

        // Replace hash with 1 based count

        return str_ireplace('{#}', ($this->count() + 1) , $value);
    }
    else {
        $fields = array();
        foreach(array_values($this->args('fields')) as $field_args) {
            $field = new CMB2_Field(array(
                'field_args' => $field_args,
                'group_field' => $this,
            ));
            $fields[$field_args['id']] = $field->value;
        }

        return call_user_func($this->options('group_title_callback') , $fields);
    }
}

Then in my metabox setup, I set:

'group_title' => 'New Widget',
'group_title_callback' => array($this, 'format_group_title'),

and finally my formatting callback that sets the title based off the field values:

public function format_group_title($fields) {
        return $fields['time'] . ' ' . $fields['name'];
}

This results in new items having the title “New Widget”, and existing groups getting an informative title based off two fields.

It’s a bit of a hack, is there a way to do this without editing CMB2? I’d rather not break automatic updates and maintain my own fork.

Edit: improved slightly