Warning: Use of undefined constant list_all – assumed ‘list_all’ (this will throw an Error in a future version of PHP)

There is a bug in this code:

    add_menu_page('Simple Table Manager - List', 'Simple Table Manager', 'manage_options', $this->slug['list'], array($this, list_all ));

The part array($this, list_all ) is a function callback, but there should be name of a function passed as string as second item in the array. So it should be:

array($this, 'list_all' )

PS. It should have been a problem with earlier versions of PHP too…