Hi Henrik, > (rel feeds (+List +Ref +Link) NIL (+Feed)) > ... > (put> Usr 'feeds Feed) > ... > (dm addFeed> (F) > (let Feeds (; This feeds) > (push1 'Feeds F) > (put!> This 'feeds Feeds))) > ... > The first example of assignment seems to imply that put> will automatically > take care of adding a new feed to the list, ie. not replacing the whole list
Correct. The 'put>' methods of the relation classes which handle compound structures (+List and +Bag) behave somewhat intelligently if they get (and detect) partial data. The reason was partially for the GUI, I think, where a +Bag maps to a +Chart and must be able to accept incomplete data. So the 'addFeed>' method above is not really necessary. You might even say it is wrong, as it gets the old list with (; This feeds), modifies it, and then calls 'put!>'. Then the whole operation is non-atomic, and another process could modify the list meanwhile. > (dm removeFeed> (F) > (put!> This 'feeds (delete F (; This feeds)))) This situation is similar. Note that you can use 'del!>' here: (del!> This 'feeds F) (However, this is not available for +Bag) Cheers, - Alex -- UNSUBSCRIBE: mailto:picol...@software-lab.de?subject=unsubscribe
