/
properties.rb
40 lines (34 loc) · 911 Bytes
/
properties.rb
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# From: http://www.infoq.com/articles/properties-metaprogramming
module Properties
def self.extended(base)
base.class_eval %{
def fire_event_for(sym, arg)
return if !@listener[sym]
@listener[sym].each {|l| l.call(arg) }
end
}
end
# def property(sym, &predicate)
def property(sym, predicate=nil)
define_method(sym) do
instance_variable_get("@#{sym}")
end
define_method("#{sym}=") do |arg|
return if !predicate.call(arg) if predicate
instance_variable_set("@#{sym}", arg)
fire_event_for(sym, arg)
end
define_method("add_#{sym}_listener") do |x|
@listener ||= {}
@listener[sym] ||= []
@listener[sym] << x
end
define_method("remove_#{sym}_listener") do |x|
return if !@listener[sym]
@listener[sym].delete_at(x)
end
end
def is(test)
lambda {|val| test === val }
end
end