Joel VanderWerf
2/1/2005 4:04:00 PM
Hugh Sasse Staff Elec Eng wrote:
> I suspect that I won't be able to use Observable because both sides
> observe and are observed by the controller, creating a loop.
If you're considering obervable attributes (the poorly named
"observable" on raa), then loops are fine. There's even an example with
cycles:
module CycleExample
class Gossip
attr_accessor :friends
observable :news
def initialize
@friends = []
@news = "No news."
when_news CHANGES do |new_value|
@friends.each {|friend| friend.news = new_value}
end
end
end
g = (0..8).collect {Gossip.new}
# make a complex network with cycles
g[0].friends = [g[1], g[2]]
g[1].friends = [g[3], g[4]]
g[2].friends = [g[4], g[5]]
g[3].friends = [g[0]]
g[4].friends = [g[2]]
g[5].friends = [g[3], g[6]]
g[6].friends = [] # doesn't tell anyone (not strongly connected)
g[7].friends = [] # nobody tells g[7] (not connected at all)
g[8].friends = [g[0]] # nobody tells g[8], but g[8] would tell g[0]
g[0].news = "I've got a girl and Ruby is her name."
puts (0..g.size-1).map {|i| "g[#{i}].news = #{g[i].news.inspect}"}
# Output:
# g[0].news = "I've got a girl and Ruby is her name."
# g[1].news = "I've got a girl and Ruby is her name."
# g[2].news = "I've got a girl and Ruby is her name."
# g[3].news = "I've got a girl and Ruby is her name."
# g[4].news = "I've got a girl and Ruby is her name."
# g[5].news = "I've got a girl and Ruby is her name."
# g[6].news = "I've got a girl and Ruby is her name."
# g[7].news = "No news."
# g[8].news = "No news."
end