no dash in the instance name

[zetoun17]

juste a tip :never use the dash '-' in the instance name !
it will be saved a and underscore '_' .

eg :
$attachments = new Attachments( 'my-att' );
// will be saved as 'my_att' in the post meta

[jchristopher]

Yes you are correct, this is a result of the name eventually making it's way to being an object property, and the syntax for retrieving that isn't familiar to everyone. I'm going to leave this Issue open for the time being, however, because I think this can be thought out a bit more...