that the method accepts multiple arguments

message quote fix

We have to use Observer#update rather than Observer#send since the enabled state is checked in #update before forwarding the method call on.

Now that we propagate the enabling/disabling to descendants, we no longer have to check the disabled_observer Set on each superclass of the model class.  This was causing a bug when disabling all observers at a superclass level and then enabling an individual observer at a subclass level.

Plus the logic is simpler now :).

Fix dev env memory leaks by using AS::DescendantsTracker rather than keeping track of subclasses manually.

There's also no need to keep track of all ObserverArray instances in a hash, as this is likely to leak memory, too.

This reverts commit 2a25c581.

I'm going to add another commit that keeps the same behavior of fixes
the problems of leaking memory in development.

This reverts commit ad62f192 because the current
subclasses implementation leaks memory in development.

Instead of keeping an array of subclasses, the better solution is to
ask the parent if an observer is being disabled or not.

Last call wins.

This is useful in situations like model unit tests and the occasional rake task to backfill old data.

ActiveModel::Observer and ActiveRecord::Observer have similar
documentation, but a Rails user looking at the ActiveModel version
might not realize that a change to config/application.rb is
required to activate the observer. This change adds a note to
that effect, pointing to the AR version from the AM version.

Signed-off-by: NJosé Valim <jose.valim@gmail.com>

Signed-off-by: NJosé Valim <jose.valim@gmail.com>

This removes ActiveModel dependency on TZInfo.

[#4979 state:committed]
Signed-off-by: NJosé Valim <jose.valim@gmail.com>

`Observable#notify_observers` from Ruby always returns false (which halts ActiveRecord
callback chains) and has extra features (like `changed`) that were never used.
Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>