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Contents
module Xcake
# This namespace provides all of methods for
# implementing the Vistor in the Visitor pattern.
#
# This implementation has a slight twist where
# a visitor knows when it has "left" an object
# it is visiting.
#
# Classes implementing these methods should
# add methods `visit_<visitable classname>`
# and `leave_<visitable classname>` for each
# visitable they intend to use that class with.
#
# @example Implementing Visitor Pattern
#
# class Writer
#
# include Visitor
#
# def visit_page
# #Write Page
# end
#
# def leave_page
# #Append Footer
# end
# end
#
module Visitor
# This is called when a visitor is visiting a
# visitable item.
#
# By default this method calls the method
# `visit_<visitable classname>` so make sure
# you've created a method for each visitable you
# intend to visit.
#
# @param [Visitable] visitable
# the visitable item the visitor is visiting
#
def visit(item)
item_name = item_name(item)
method = "visit_#{item_name}"
send(method, item) if respond_to? method
end
# This is called when a visitor is leaving a
# visitable item.
#
# By default this method calls the method
# `leave_<visitable classname>` so make sure
# you've created a method for each visitable you
# intend to visit.
#
# @param [Visitable] visitable
# the visitable item the visitor has left
#
def leave(item)
item_name = item_name(item)
method = "leave_#{item_name}"
send(method, item) if respond_to? method
end
private
def item_name(item)
class_name = item.class.to_s
class_name.gsub!('Xcake::', '')
class_name.gsub!('::', '_')
class_name.downcase!
end
end
end
Version data entries
16 entries across 16 versions & 1 rubygems