| Class | Jabber::CallbackList |
| In: |
lib/xmpp4r/callbacks.rb
|
| Parent: | Object |
This class manages a list of callbacks.
Callbacks are managed by the class CallbackList. When they are added, a priority (just a number or anything Comparable with other priorities) is specified. The biggest the priority is, the earliest the callback will be considered.
Callbacks are processed for a given set of objects as long as they return false. If you want to stop processing, you must return true. Example :
cbl = CallbackList.new
c1 = false
c2 = false
c3 = false
cbl.add(10) { c1 = true; 1 }
cbl.add(5) { c2 = true; true }
cbl.add(0) { c3 = true }
cbl.process('aa')
puts "#{c1} #{c2} #{c3}"
This example would display "true true false" as callbacks processing was stopped after the second callback returned true.
In XMPP4R, callbacks’ priorities are quite normalized since we want to be able to "cascade" callbacks in a clean way. Here are values your code should take into account :
| >= 200: | logging & debugging callbacks. Those callbacks should not consume elements. |
| 100-199: | Where Helpers register their callbacks. The normal value is 100, and Helpers shouldn‘t register something else unless there‘s a very good reason to. |
| < 100: | all those numbers are normally available for your application. That‘s enough, don‘t you think ? |
Add a callback to the list
List will be sorted afterwards
| prio: | [Integer] the callback‘s priority, the higher, the sooner. |
| ref: | [String] the callback‘s reference |
| block: | [Block] a block to execute |
| return: | [Jabber::CallbackList] The list, for chaining |
# File lib/xmpp4r/callbacks.rb, line 57
57: def add(prio = 0, ref = nil, proc = nil, &block)
58: block = proc if proc
59: @list.push(Callback.new(prio, ref, block))
60: @list.sort! { |a, b| b.priority <=> a.priority }
61: self
62: end
Number of elements in the list
| return: | [Integer] The number of elements |
# File lib/xmpp4r/callbacks.rb, line 76
76: def length
77: @list.length
78: end
Process an element through all my callbacks. returns e.consumed?
| e: | [Object] The elements to pass to the callback. You can pass |
several, but of course, you block must know how to handle them.
| return: | [Boolean] true if the element has been consumed |
# File lib/xmpp4r/callbacks.rb, line 85
85: def process(*e)
86: # If somebody adds a new callback the list will get modified
87: # and sorted(!) while still iterating through it. So we use a
88: # local copy of @list. Any freshly added callback will receive
89: # the next stanzas, not the current.
90: list = @list.dup
91:
92: # process through callbacks
93: list.each do |item|
94: return true if item.block.call(*e) == true
95: end
96: false
97: end