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controller.rb
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controller.rb
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# Copyright, 2016, by Samuel G. D. Williams. <http://www.codeotaku.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
module Synco
# Basic event handling and delegation.
class Controller
def self.build(*arguments, **options, &block)
controller = self.new(*arguments, **options)
if block_given?
yield(controller)
end
controller.freeze
return controller
end
def initialize
@events = Hash.new{|hash,key| hash[key] = Array.new}
@aborted = false
end
def freeze
@events.freeze
super
end
attr :events
# Register an event handler which may be triggered when an event is fired.
def on(event, &block)
@events[event] << block
end
# Fire an event which calls all registered event handlers in the order they were defined.
# The first argument is used to #instance_eval any handlers.
def fire(event, *args)
return false unless @events.key?(event)
handled = false
scope = args.shift
@events[event].each do |handler|
handled = true
if scope
scope.instance_exec(*args, &handler)
else
handler.call
end
end
return handled
end
# Try executing a given block of code and fire appropriate events.
#
# The sequence of events (registered via #on) are as follows:
# [+:prepare+] Fired before the block is executed. May call #abort! to cancel execution.
# [+:success+] Fired after the block of code has executed without raising an exception.
# [+:failure+] Fired if an exception is thrown during normal execution.
# [+:finish+] Fired at the end of execution regardless of failure.
#
# If #abort! has been called in the past, this function returns immediately.
def try(*arguments)
return if @aborted
begin
catch(abort_name) do
fire(:prepare, *arguments)
yield
fire(:success, *arguments)
end
rescue Exception => exception
# Propagage the exception unless it was handled in some specific way.
raise unless fire(:failure, *arguments, exception)
ensure
fire(:finish, *arguments)
end
end
# Abort the current event handler. Aborting an event handler persistently implies that in
# the future it will still be aborted; thus calling #try will have no effect.
def abort!(persistent = false)
@aborted = true if persistent
throw abort_name
end
private
# The name used for throwing abortions.
def abort_name
("abort_" + self.class.name).downcase.to_sym
end
end
end