59 lines
1.7 KiB
Ruby
59 lines
1.7 KiB
Ruby
class Module
|
|
# Encapsulates the common pattern of:
|
|
#
|
|
# alias_method :foo_without_feature, :foo
|
|
# alias_method :foo, :foo_with_feature
|
|
#
|
|
# With this, you simply do:
|
|
#
|
|
# alias_method_chain :foo, :feature
|
|
#
|
|
# And both aliases are set up for you.
|
|
#
|
|
# Query and bang methods (foo?, foo!) keep the same punctuation:
|
|
#
|
|
# alias_method_chain :foo?, :feature
|
|
#
|
|
# is equivalent to
|
|
#
|
|
# alias_method :foo_without_feature?, :foo?
|
|
# alias_method :foo?, :foo_with_feature?
|
|
#
|
|
# so you can safely chain foo, foo?, and foo! with the same feature.
|
|
def alias_method_chain(target, feature)
|
|
# Strip out punctuation on predicates or bang methods since
|
|
# e.g. target?_without_feature is not a valid method name.
|
|
aliased_target, punctuation = target.to_s.sub(/([?!=])$/, ''), $1
|
|
yield(aliased_target, punctuation) if block_given?
|
|
alias_method "#{aliased_target}_without_#{feature}#{punctuation}", target
|
|
alias_method target, "#{aliased_target}_with_#{feature}#{punctuation}"
|
|
end
|
|
|
|
# Allows you to make aliases for attributes, which includes
|
|
# getter, setter, and query methods.
|
|
#
|
|
# Example:
|
|
#
|
|
# class Content < ActiveRecord::Base
|
|
# # has a title attribute
|
|
# end
|
|
#
|
|
# class Email < ActiveRecord::Base
|
|
# alias_attribute :subject, :title
|
|
# end
|
|
#
|
|
# e = Email.find(1)
|
|
# e.title # => "Superstars"
|
|
# e.subject # => "Superstars"
|
|
# e.subject? # => true
|
|
# e.subject = "Megastars"
|
|
# e.title # => "Megastars"
|
|
def alias_attribute(new_name, old_name)
|
|
module_eval <<-STR, __FILE__, __LINE__+1
|
|
def #{new_name}; #{old_name}; end
|
|
def #{new_name}?; #{old_name}?; end
|
|
def #{new_name}=(v); self.#{old_name} = v; end
|
|
STR
|
|
end
|
|
end
|