29 Nov
2007
29 Nov
'07
8 a.m.
Ok, I have a Person class and a House class. Each of
these has a
class side method called #register: that stores the instance in an
ordered collection of the class side. Person and House both have full
descriptions and are capable of displaying themselves, so the
"manager" class just allows one to make many of these.
Ok, got it.
This is where I need the custom memento (and tell me
if I'm doing this
wrong): If you click save that winds up calling "commit" on the
memento and actually writing the data to the object, but this new
object wont be registered in the class side collection (and therefor
will simply cease to exist when this session expires). So my custom
memento simply lets everything work as normal and then calls "Person
register: self model" to get the new object registered.
Sure that's a possibility, but why not use the return value if you are
using #call: or set an #onAnswer: handler if you are using composition?
So in your manager you have something along:
house := self call: House new asComponent.
house ifNotNil: [ House register: house ].
or (in case of composition):
editor := House new asComponent onAnswer: [ :house |
house ifNotNil: [ House register: house ].
editor := nil ]
The problem happens when "save" returns on
Person and you go back to
the manager page. You see your nice new Person in the report table as
expected, but right below is the same Person again! And if you edit
either one the changes reflect in both. And the really hairy thing
is, even though House is almost exactly the same in every way (I can
find no relevant difference) it doesn't have this behavior.
Looks like your memento method gets called twice? Why not check if the
object is already present? Why not use a Set then?
Cheers,
Lukas
--
Lukas Renggli
http://www.lukas-renggli.ch