instance method
delegate_missing_to
Ruby on Rails 5.1.7
Since v5.1.7Signature
delegate_missing_to(target)When building decorators, a common pattern may emerge:
class Partition
def initialize(first_event)
@events = [ first_event ]
end
def people
if @events.first.detail.people.any?
@events.collect { |e| Array(e.detail.people) }.flatten.uniq
else
@events.collect(&:creator).uniq
end
end
private
def respond_to_missing?(name, include_private = false)
@events.respond_to?(name, include_private)
end
def method_missing(method, *args, &block)
@events.send(method, *args, &block)
end
end
With ‘Module#delegate_missing_to`, the above is condensed to:
class Partition
delegate_missing_to :@events
def initialize(first_event)
@events = [ first_event ]
end
def people
if @events.first.detail.people.any?
@events.collect { |e| Array(e.detail.people) }.flatten.uniq
else
@events.collect(&:creator).uniq
end
end
end
The target can be anything callable within the object. E.g. instance variables, methods, constants and the likes.
Parameters
-
targetreq
Source
# File activesupport/lib/active_support/core_ext/module/delegation.rb, line 264
def delegate_missing_to(target)
target = target.to_s
target = "self.#{target}" if DELEGATION_RESERVED_METHOD_NAMES.include?(target)
module_eval <<-RUBY, __FILE__, __LINE__ + 1
def respond_to_missing?(name, include_private = false)
# It may look like an oversight, but we deliberately do not pass
# +include_private+, because they do not get delegated.
#{target}.respond_to?(name) || super
end
def method_missing(method, *args, &block)
if #{target}.respond_to?(method)
#{target}.public_send(method, *args, &block)
else
super
end
end
RUBY
end
Defined in activesupport/lib/active_support/core_ext/module/delegation.rb line 264
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Defined in Module