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## signal-system.rb --- simple intra-process signal system
# Copyright (C) 2005 Daniel Brockman
# This program is free software; you can redistribute it
# and/or modify it under the terms of the GNU General Public
# License as published by the Free Software Foundation;
# either version 2 of the License, or (at your option) any
# later version.
# This file is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty
# of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the GNU General Public License for more details.
# You should have received a copy of the GNU General Public
# License along with this program; if not, write to the Free
# Software Foundation, 51 Franklin Street, Fifth Floor,
# Boston, MA 02110-1301, USA.
require "puppet/external/event-loop/better-definers"
module SignalEmitterModule
def self.extended (object)
if object.kind_of? Module and not object < SignalEmitter
if object.respond_to? :fcall
# This is the way to call private methods
# in Ruby 1.9 as of November 16.
object.fcall :include, SignalEmitter
else
object.__send__ :include, SignalEmitter
end
end
end
def define_signal (name, slot=:before, &body)
# Can't use `define_method' and take a block pre-1.9.
class_eval %{ def on_#{name} &block
add_signal_handler(:#{name}, &block) end }
define_signal_handler(name, :before, &lambda {|*a|})
define_signal_handler(name, :after, &lambda {|*a|})
define_signal_handler(name, slot, &body) if block_given?
end
def define_signals (*names, &body)
names.each { |x| define_signal(x, &body) }
end
def define_signal_handler (name, slot=:before, &body)
case slot
when :before
define_protected_method "handle_#{name}", &body
when :after
define_protected_method "after_handle_#{name}", &body
else
raise ArgumentError, "invalid slot `#{slot.inspect}'; " +
"should be `:before' or `:after'", caller(1)
end
end
end
# This is an old name for the same thing.
SignalEmitterClass = SignalEmitterModule
module SignalEmitter
def self.included (includer)
if not includer.kind_of? SignalEmitterClass
includer.extend SignalEmitterClass
end
end
def __maybe_initialize_signal_emitter
@signal_handlers ||= Hash.new { |h, k| h[k] = Array.new }
@allow_dynamic_signals ||= false
end
define_accessors :allow_dynamic_signals?
def add_signal_handler (name, &handler)
__maybe_initialize_signal_emitter
@signal_handlers[name] << handler
return handler
end
define_soft_aliases [:on, :on_signal] => :add_signal_handler
def remove_signal_handler (name, handler)
__maybe_initialize_signal_emitter
@signal_handlers[name].delete(handler)
end
def __signal__ (name, *args, &block)
__maybe_initialize_signal_emitter
respond_to? "on_#{name}" or allow_dynamic_signals? or
fail "undefined signal `#{name}' for #{self}:#{self.class}"
__send__("handle_#{name}", *args, &block) if
respond_to? "handle_#{name}"
@signal_handlers[name].each { |x| x.call(*args, &block) }
__send__("after_handle_#{name}", *args, &block) if
respond_to? "after_handle_#{name}"
end
define_soft_alias :signal => :__signal__
end
# This module is indended to be a convenience mixin to be used by
# classes whose objects need to observe foreign signals. That is,
# if you want to observe some signals coming from an object, *you*
# should mix in this module.
#
# You cannot use this module at two different places of the same
# inheritance chain to observe signals coming from the same object.
#
# XXX: This has not seen much use, and I'd like to provide a
# better solution for the problem in the future.
module SignalObserver
def __maybe_initialize_signal_observer
@observed_signals ||= Hash.new do |signals, object|
signals[object] = Hash.new do |handlers, name|
handlers[name] = Array.new
end
end
end
def observe_signal (subject, name, &handler)
__maybe_initialize_signal_observer
@observed_signals[subject][name] << handler
subject.add_signal_handler(name, &handler)
end
def map_signals (source, pairs={})
pairs.each do |src_name, dst_name|
observe_signal(source, src_name) do |*args|
__signal__(dst_name, *args)
end
end
end
def absorb_signals (subject, *names)
names.each do |name|
observe_signal(subject, name) do |*args|
__signal__(name, *args)
end
end
end
define_soft_aliases \
:map_signal => :map_signals,
:absorb_signal => :absorb_signals
def ignore_signal (subject, name)
__maybe_initialize_signal_observer
__ignore_signal_1(subject, name)
@observed_signals.delete(subject) if
@observed_signals[subject].empty?
end
def ignore_signals (subject, *names)
__maybe_initialize_signal_observer
names = @observed_signals[subject] if names.empty?
names.each { |x| __ignore_signal_1(subject, x) }
end
private
def __ignore_signal_1(subject, name)
@observed_signals[subject][name].each do |handler|
subject.remove_signal_handler(name, handler) end
@observed_signals[subject].delete(name)
end
end
if __FILE__ == $0
require "test/unit"
class SignalEmitterTest < Test::Unit::TestCase
class X
include SignalEmitter
define_signal :foo
end
def setup
@x = X.new
end
def test_on_signal
moomin = 0
@x.on_signal(:foo) { moomin = 1 }
@x.signal :foo
assert moomin == 1
end
def test_on_foo
moomin = 0
@x.on_foo { moomin = 1 }
@x.signal :foo
assert moomin == 1
end
def test_multiple_on_signal
moomin = 0
@x.on_signal(:foo) { moomin += 1 }
@x.on_signal(:foo) { moomin += 2 }
@x.on_signal(:foo) { moomin += 4 }
@x.on_signal(:foo) { moomin += 8 }
@x.signal :foo
assert moomin == 15
end
def test_multiple_on_foo
moomin = 0
@x.on_foo { moomin += 1 }
@x.on_foo { moomin += 2 }
@x.on_foo { moomin += 4 }
@x.on_foo { moomin += 8 }
@x.signal :foo
assert moomin == 15
end
end
end
## application-signals.rb ends here.
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